1IPSEC.CONF(5)                 Executable programs                IPSEC.CONF(5)
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NAME

6       ipsec.conf - IPsec configuration and connections
7

DESCRIPTION

9       The ipsec.conf file specifies most configuration and control
10       information for the Libreswan IPsec subsystem. (The major exception is
11       secrets for authentication; see ipsec.secrets(5).) Its contents are not
12       security-sensitive. Configurations can be added using this
13       configuration file or by using ipsec whack directly. This means that
14       technically, the ipsec.conf file is optional, but a few warnings might
15       show up when this file is missing.
16
17       ipsec.conf is a text file, consisting of one or more sections. White
18       space followed by # followed by anything to the end of the line is a
19       comment and is ignored, as are empty lines that are not within a
20       section.
21
22       A line that contains include and a file name, separated by white space,
23       is replaced by the contents of that file, preceded and followed by
24       empty lines. If the file name is not a full pathname, it is considered
25       to be relative to the directory that contains the including file. Such
26       inclusions can be nested. Only a single filename may be supplied, and
27       it may not contain white space, but it may include shell wildcards (see
28       sh(1)); for example:
29
30       include /etc/ipsec.d/*.conf
31
32       The intention of the include facility is mostly to permit keeping
33       information on connections, or sets of connections, separate from the
34       main configuration file. This permits such connection descriptions to
35       be changed, copied to the other security gateways involved, etc.,
36       without having to constantly extract them from the configuration file
37       and then insert them back into it. Note also the also and alsoflip
38       parameters (described below) which permit splitting a single logical
39       section (e.g. a connection description) into several distinct sections.
40
41       The first significant line of the file may specify a version of this
42       specification for backwards compatibility with freeswan and openswan.
43       It is ignored and unused. For compatibility with openswan, specify:
44
45       version 2
46
47       A section begins with a line of the form:
48
49       type name
50
51       where type indicates what type of section follows, and name is an
52       arbitrary name that distinguishes the section from others of the same
53       type. (Names must start with a letter and may contain only letters,
54       digits, periods, underscores, and hyphens.) All subsequent non-empty
55       lines that begin with white space are part of the section; comments
56       within a section must begin with white space too. There may be only one
57       section of a given type with a given name.
58
59       Lines within the section are generally of the form
60
61            parameter=value
62
63       (note the mandatory preceding white space). There can be white space on
64       either side of the =. Parameter names follow the same syntax as section
65       names, and are specific to a section type. Unless otherwise explicitly
66       specified, no parameter name may appear more than once in a section.
67
68       An empty value stands for the system default value (if any) of the
69       parameter, i.e. it is roughly equivalent to omitting the parameter line
70       entirely. A value may contain white space only if the entire value is
71       enclosed in double quotes ("); a value cannot itself contain a double
72       quote, nor may it be continued across more than one line.
73
74       Numeric values are specified to be either an “integer” (a sequence of
75       digits) or a “decimal number” (sequence of digits optionally followed
76       by `.' and another sequence of digits).
77
78       There is currently one parameter that is available in any type of
79       section:
80
81       also
82           the value is a section name; the parameters of that section are
83           appended to this section, as if they had been written as part of
84           it. The specified section must exist, must follow the current one,
85           and must have the same section type. (Nesting is permitted, and
86           there may be more than one also in a single section, although it is
87           forbidden to append the same section more than once.) This allows,
88           for example, keeping the encryption keys for a connection in a
89           separate file from the rest of the description, by using both an
90           also parameter and an include line. (Caution, see BUGS below for
91           some restrictions.)
92
93       alsoflip
94           can be used in a conn section. It acts like an also that flips the
95           referenced section's entries left-for-right.
96
97       Parameter names beginning with x- (or X-, or x_, or X_) are reserved
98       for user extensions and will never be assigned meanings by IPsec.
99       Parameters with such names must still observe the syntax rules (limits
100       on characters used in the name; no white space in a non-quoted value;
101       no newlines or double quotes within the value). All other as-yet-unused
102       parameter names are reserved for future IPsec improvements.
103
104       A section with name %default specifies defaults for sections of the
105       same type. For each parameter in it, any section of that type that does
106       not have a parameter of the same name gets a copy of the one from the
107       %default section. There may be multiple %default sections of a given
108       type, but only one default may be supplied for any specific parameter
109       name.  %default sections may not contain also or alsoflip parameters.
110
111       Currently there are two types of section: a config section specifies
112       general configuration information for IPsec, while a conn section
113       specifies an IPsec connection.
114

CONN SECTIONS

116       A conn section contains a connection specification, defining a network
117       connection to be made using IPsec. The name given is arbitrary, and is
118       used to identify the connection to ipsec_auto(8) Here's a simple
119       example:
120
121
122           conn snt
123                left=10.11.11.1
124                leftsubnet=10.0.1.0/24
125                leftnexthop=172.16.55.66
126                leftsourceip=10.0.1.1
127                right=192.168.22.1
128                rightsubnet=10.0.2.0/24
129                rightnexthop=172.16.88.99
130                rightsourceip=10.0.2.1
131                keyingtries=%forever
132
133       A note on terminology... In automatic keying, there are two kinds of
134       communications going on: transmission of user IP packets, and
135       gateway-to-gateway negotiations for keying, rekeying, and general
136       control. The data path (a set of “IPsec SAs”) used for user packets is
137       herein referred to as the “connection”; the path used for negotiations
138       (built with “ISAKMP SAs”) is referred to as the “keying channel”.
139
140       To avoid trivial editing of the configuration file to suit it to each
141       system involved in a connection, connection specifications are written
142       in terms of left and right participants, rather than in terms of local
143       and remote. Which participant is considered left or right is arbitrary;
144       IPsec figures out which one it is being run on based on internal
145       information. This permits using identical connection specifications on
146       both ends. There are cases where there is no symmetry; a good
147       convention is to use left for the local side and right for the remote
148       side (the first letters are a good mnemonic).
149
150       Many of the parameters relate to one participant or the other; only the
151       ones for left are listed here, but every parameter whose name begins
152       with left has a right counterpart, whose description is the same but
153       with left and right reversed.
154
155       Parameters are optional unless marked “(required)”
156
157   CONN PARAMETERS: GENERAL
158       The following parameters are relevant to IKE automatic keying. Unless
159       otherwise noted, for a connection to work, in general it is necessary
160       for the two ends to agree exactly on the values of these parameters.
161
162       keyexchange
163           method of key exchange; the default and currently the only accepted
164           value is ike
165
166       hostaddrfamily
167           the address family of the hosts; currently the accepted values are
168           ipv4 and ipv6. The default is to detect this based on the IP
169           addresses specified or the IP addresses resolved, so this option is
170           not needed, unless you specify hostnames that resolve to both IPv4
171           and IPv6. This option used to be named connaddrfamily but its use
172           was broken so it was obsoleted in favour or using the new
173           hostaddrfamily and clientaddrfamily.
174
175       clientaddrfamily
176           the address family of the clients (subnets); currently the accepted
177           values are ipv4 and ipv6. The default is to detect this based on
178           the network IP addresses specified or the network IP addresses
179           resolved, so this option is not needed, unless you specify names
180           that resolve to both IPv4 and IPv6.
181
182       type
183           the type of the connection; currently the accepted values are
184           tunnel (the default) signifying a host-to-host, host-to-subnet, or
185           subnet-to-subnet tunnel; transport, signifying host-to-host
186           transport mode; passthrough, signifying that no IPsec processing
187           should be done at all; drop, signifying that packets should be
188           discarded; and reject, signifying that packets should be discarded
189           and a diagnostic ICMP returned.
190
191       left
192           (required) the IP address or DNS hostname of the left participant's
193           public-network interface, Currently, IPv4 and IPv6 IP addresses are
194           supported. If a DNS hostname is used, it will be resolved to an IP
195           address on load time, and whenever a connection is rekeying or
196           restarting (such as when restarted via a DPD failure detection).
197           This allows one to use a DNS hostname when the endpoint is on a
198           dynamic IP address.
199
200           There are several magic values. If it is %defaultroute, left will
201           be filled in automatically with the local address of the
202           default-route interface (as determined at IPsec startup time); this
203           also overrides any value supplied for leftnexthop. (Either left or
204           right may be %defaultroute, but not both.) The value %any signifies
205           an address to be filled in (by automatic keying) during
206           negotiation. The value %opportunistic signifies that both left and
207           leftnexthop are to be filled in (by automatic keying) from DNS data
208           for left's client. The value can also contain the interface name,
209           which will then later be used to obtain the IP address from to fill
210           in. For example %ppp0. The values %group and %opportunisticgroup
211           makes this a policy group conn: one that will be instantiated into
212           a regular or opportunistic conn for each CIDR block listed in the
213           policy group file with the same name as the conn.
214
215           If using IP addresses in combination with NAT, always use the
216           actual local machine's (NATed) IP address, and if the remote (eg
217           right=) is NATed as well, the remote's public (not NATed) IP
218           address. Note that this makes the configuration no longer
219           symmetrical on both sides, so you cannot use an identical
220           configuration file on both hosts.
221
222       leftsubnet
223           private subnet behind the left participant, expressed as
224           network/netmask (actually, any form acceptable to
225           ipsec_ttosubnet(3)); Currently, IPv4 and IPv6 ranges are supported.
226           if omitted, essentially assumed to be left/32, signifying that the
227           left end of the connection goes to the left participant only
228
229           It supports two magic shorthands vhost: and vnet:, which can list
230           subnets in the same syntax as virtual-private. The value %priv
231           expands to the networks specified in virtual-private. The value %no
232           means no subnet. A common use for allowing roadwarriors to come in
233           on public IPs or via accepted NATed networks from RFC1918 is to use
234           leftsubnet=vhost:%no,%priv. The vnet: option can be used to allow
235           RFC1918 subnets without hardcoding them. When using vnet the
236           connection will instantiate, allowing for multiple tunnels with
237           different subnets.
238
239       leftsubnets
240           specify multiple private subnets behind the left participant,
241           expressed as { networkA/netmaskA, networkB/netmaskB [...]  } If
242           both a leftsubnets= and rightsubnets= are defined, all combinations
243           of subnet tunnels will be established as IPsec tunnels. You cannot
244           use leftsubnet= and leftsubnets= together. For examples see
245           testing/pluto/multinet-*. Be aware that when using spaces as
246           separator, that the entire option value needs to be in double
247           quotes.
248
249       leftvti
250           the address/mask to configure on the VTI interface when
251           vti-interface is set. It takes the form of network/netmask
252           (actually, any form acceptable to ipsec_ttosubnet(3)); Currently,
253           IPv4 and IPv6 ranges are supported. This option is often used in
254           combination with routed based VPNs.
255
256       leftaddresspool
257           address pool from where the IKEv1 ModeCFG or IKEv2 server can
258           assign IP addresses to clients. When configured as a server, using
259           leftxauthserver=yes this option specifies the address pool from
260           which IP addresses are taken to assign the clients. The syntax of
261           the address pool specifies a range (not a CIDR) for IPv4 and CIDR
262           for IPv6, in the following syntax:
263           rightaddresspool=192.168.1.100-192.168.1.200 or
264           rightaddresspool=2001:db8:0:3:1::/97 Generally, the
265           rightaddresspool= option will be accompanied by
266           rightxauthclient=yes, leftxauthserver=yes and leftsubnet=0.0.0.0/0
267           option.
268
269           When leftaddresspool= is specified, the connection may not specify
270           either leftsubnet= or leftsubnets=. Address pools are fully
271           allocated when the connection is loaded, so the ranges should be
272           sane. For example, specifying a range
273           rightaddresspool=10.0.0.0-11.0.0.0 will lead to massive memory
274           allocation. Address pools specifying the exact same range are
275           shared between different connections. Different addresspools should
276           not be defined to partially overlap.
277
278       leftprotoport
279           allowed protocols and ports over connection, also called Port
280           Selectors. The argument is in the form protocol, which can be a
281           number or a name that will be looked up in /etc/protocols, such as
282           leftprotoport=icmp, or in the form of protocol/port, such as
283           tcp/smtp. Ports can be defined as a number (eg. 25) or as a name
284           (eg smtp) which will be looked up in /etc/services. A special
285           keyword %any can be used to allow all ports of a certain protocol.
286           The most common use of this option is for L2TP connections to only
287           allow l2tp packets (UDP port 1701), eg: leftprotoport=17/1701.
288
289           To filter on specific icmp type and code, use the higher 8 bits for
290           type and the lower 8 bits for port. For example, to allow icmp echo
291           packets (type 8, code 0) the 'port' would be 0x0800, or 2048 in
292           decimal, so you configure leftprotoport=icmp/2048. Similarly, to
293           allow ipv6-icmp Neighbour Discovery which has type 136 (0x88) and
294           code 0(0x00) this becomes 0x8800 or in decimal 34816 resulting in
295           leftprotoport=ipv6-icmp/34816 .
296
297           Some clients, notably older Windows XP and some Mac OSX clients,
298           use a random high port as source port. In those cases
299           rightprotoport=17/%any can be used to allow all UDP traffic on the
300           connection. Note that this option is part of the proposal, so it
301           cannot be arbitrarily left out if one end does not care about the
302           traffic selection over this connection - both peers have to agree.
303           The Port Selectors show up in the output of ipsec eroute and ipsec
304           auto --status eg:"l2tp":
305           193.110.157.131[@aivd.libreswan.org]:7/1701...%any:17/1701 This
306           option only filters outbound traffic. Inbound traffic selection
307           must still be based on firewall rules activated by an updown
308           script. The variables $PLUTO_MY_PROTOCOL, $PLUTO_PEER_PROTOCOL,
309           $PLUTO_MY_PORT, and $PLUTO_PEER_PORT are available for use in
310           updown scripts. Older workarounds for bugs involved a setting of
311           17/0 to denote any single UDP port (not UDP port 0). Some clients,
312           most notably OSX, uses a random high port, instead of port 1701 for
313           L2TP.
314
315       leftnexthop
316           next-hop gateway IP address for the left participant's connection
317           to the public network; defaults to %direct (meaning right). If the
318           value is to be overridden by the left=%defaultroute method (see
319           above), an explicit value must not be given. If that method is not
320           being used, but leftnexthop is %defaultroute, and
321           interfaces=%defaultroute is used in the config setup section, the
322           next-hop gateway address of the default-route interface will be
323           used. The magic value %direct signifies a value to be filled in (by
324           automatic keying) with the peer's address. Relevant only locally,
325           other end need not agree on it.
326
327       leftsourceip
328           the IP address for this host to use when transmitting a packet to
329           the other side of this link. Relevant only locally, the other end
330           need not agree. This option is used to make the gateway itself use
331           its internal IP, which is part of the leftsubnet, to communicate to
332           the rightsubnet or right. Otherwise, it will use its nearest IP
333           address, which is its public IP address. This option is mostly used
334           when defining subnet-subnet connections, so that the gateways can
335           talk to each other and the subnet at the other end, without the
336           need to build additional host-subnet, subnet-host and host-host
337           tunnels. Both IPv4 and IPv6 addresses are supported.
338
339       leftupdown
340           what "updown" script to run to adjust routing and/or firewalling
341           when the status of the connection changes (default ipsec _updown).
342           May include positional parameters separated by white space
343           (although this requires enclosing the whole string in quotes);
344           including shell metacharacters is unwise. An example to enable
345           routing when using the XFRM stack, one can use:
346
347           leftupdown="ipsec _updown --route yes"
348
349           To disable calling an updown script, set it to the empty string, eg
350           leftupdown="" or leftupdown="%disabled".
351
352           See ipsec_pluto(8) for details. Relevant only locally, other end
353           need not agree on it.
354
355       leftcat
356           Whether to perform Client Address Translation ("CAT") when using
357           Opportunistic IPsec behind NAT. Accepted values are no (the
358           default) and yes. This option should only be enabled on the special
359           Opportunistic IPsec connections, usually called "private" and
360           "private-or-clear". When set, this option causes the given
361           addresspool IP from the remote peer to be NATed with iptables. It
362           will also install an additional IPsec SA policy to cover the
363           pre-NAT IP. See the Opportunistic IPsec information on the
364           libreswan website for more information and examples.
365
366       leftfirewall
367           This option is obsolete and should not used anymore.
368
369       If one or both security gateways are doing forwarding firewalling
370       (possibly including masquerading), and this is specified using the
371       firewall parameters, tunnels established with IPsec are exempted from
372       it so that packets can flow unchanged through the tunnels. (This means
373       that all subnets connected in this manner must have distinct,
374       non-overlapping subnet address blocks.) This is done by the default
375       updown script (see ipsec_pluto(8)).
376
377       The implementation of this makes certain assumptions about firewall
378       setup, and the availability of the Linux Advanced Routing tools. In
379       situations calling for more control, it may be preferable for the user
380       to supply his own updown script, which makes the appropriate
381       adjustments for his system.
382
383   CONN PARAMETERS: AUTOMATIC KEYING
384       The following parameters are relevant to automatic keying via IKE.
385       Unless otherwise noted, for a connection to work, in general it is
386       necessary for the two ends to agree exactly on the values of these
387       parameters.
388
389       auto
390           what operation, if any, should be done automatically at IPsec
391           startup; currently-accepted values are add (signifying an ipsec
392           auto --add), ondemand (signifying that plus an ipsec auto
393           --ondemand), start (signifying that plus an ipsec auto --up), and
394           ignore (also the default) (signifying no automatic startup
395           operation), and keep (signifying an add plus an attempt to keep the
396           connection up once the remote peer brought it up). See the config
397           setup discussion below. Relevant only locally, other end need not
398           agree on it (but in general, for an intended-to-be-permanent
399           connection, both ends should use auto=start to ensure that any
400           reboot causes immediate renegotiation).
401
402           The option ondemand used to be called route
403
404       authby
405           how the two security gateways should authenticate each other; the
406           default value is rsasig,ecdsa which allows ECDSA with SHA-2 and RSA
407           with SHA2 or SHA1. To limit this further, there are the options of
408           ecdsa for ECDSA digital signatures using SHA-2, rsa-sha2 for
409           RSASSA-PSS digital signatures based authentication with SHA2-256,
410           rsa-sha2_384 for RSASSA-PSS digital signatures based authentication
411           with SHA2-384, rsa-sha2_512 for RSASSA-PSS digital signatures based
412           authentication with SHA2-512, rsa-sha1 for RSA-PKCSv1.5 digital
413           signatures based authentication with SHA1, secret for shared
414           secrets (PSK) authentication, secret|rsasig for either, never if
415           negotiation is never to be attempted or accepted (useful for
416           shunt-only conns), and null for null-authentication.
417
418           If asymmetric authentication is requested, IKEv2 must be enabled,
419           and the options leftauth= and rightauth= should be used instead of
420           authby.
421
422           For IKEv1, SHA2 based signatures are not defined and ECDSA is not
423           implemented, so the default authby= value is rsa-sha1. Using
424           authby=rsasig results in only rsa-sha1 as well. For IKEv2, using
425           authby=rsasig means using rsa-sha2_512, rsa-sha2_384, rsa-sha2_256
426           and rsa-sha1, where rsa-sha1 will used only if RFC 7427 is not
427           supported by the peer.
428
429           As per RFC 8221, authby=rsa-sha1 is only supported in the old
430           style, meaning RSA-PKCSv1.5. The SHA2 variants are only supported
431           for the new style of RFC 7427, so authby=rsa-sha2 will use the new
432           style. The default authby= will remove rsa-sha1 in the near future.
433           It is strongly recommended that if certificates are used, the
434           certificates and the authby= signature methods used are the same,
435           as it increases interoperability and keeps the authentication of
436           everything within one digital signature system.
437
438           Digital signatures are superior in every way to shared secrets.
439           Especially IKEv1 in Aggressive Mode is vulnerable to offline
440           dictionary attacks and is performed routinely by at least the NSA
441           on monitored internet traffic globally. The never option is only
442           used for connections that do not actually start an IKE negotiation,
443           such as type=passthrough connections. The auth method null is used
444           for "anonymous opportunistic IPsec" and should not be used for
445           regular pre-configured IPsec VPNs.
446
447       ike
448           IKE encryption/authentication algorithm to be used for the
449           connection (phase 1 aka ISAKMP SA or IKE SA). If this option is not
450           set, the builtin defaults will be used. This is the preferred
451           method, and allows for gradual automatic updates using the same
452           configuration. Some distributions, such as Fedora and RHEL/CentOS,
453           use a System Wide Crypto Policy that sets the default ike= (and
454           esp=) lines. Specifying your own ike= line means overriding all
455           these system or software recommended defaults, but can be necessary
456           at times. Note that libreswan does not support using a PRF
457           algorithm that is different from the INTEGRITY (hash) algorithm by
458           design.
459
460           The format is "cipher-hash;modpgroup, cipher-hash;modpgroup, ..."
461           Any omitited option will be filled in with all allowed default
462           values. Multiple proposals are separated by a comma. If an ike=
463           line is specified, no other received proposals will be accepted
464           than those specified on the IKE line. Some examples are
465           ike=3des-sha1,aes-sha1, ike=aes, ike=aes_ctr, ike=aes_gcm256-sha2,
466           ike=aes128-md5;modp2048, ike=aes256-sha2;dh19,
467           ike=aes128-sha1;dh22, ike=3des-md5;modp1024,aes-sha1;modp1536.
468
469           IKEv2 allows combining elements into a single proposal. These can
470           be specified by using the + symbol. An example is:
471           ike=aes_gcm+chacha20_poly1305;dh14+dh19,aes+3des-sha2+sha1;dh14.
472           Note that AEAD algorithms (aes_gcm, aes_ccm, chacha20_poly1305) and
473           non-AEAD algorithms (aes, 3des) cannot be combined into a single
474           proposal. To support aes and aes_gcm, two proposals separated by a
475           comma must be used.
476
477           The default IKE proposal depends on the version of libreswan used.
478           It follow the recommendations of RFC4306, RFC7321 and as of this
479           writing their successor draft documents RFC4306bis and RFC7321bis.
480           As for libreswan 3.32, SHA1 and MODP1536(dh5) are still allowed per
481           default for backwards compatibility, but 3DES and MODP1024(dh2) are
482           not allowed per default. As of libreswan 4.x, modp1024(dh2) support
483           is no longer compiled in at all. For IKEv2, the defaults include
484           AES, AES-GCM, DH14 and stronger, and SHA2. The default key size is
485           256 bits. The default AES_GCM ICV is 16 bytes.
486
487           Note that AES-GCM is an AEAD algorithm, meaning that it performs
488           encryption+authentication in one step. This means that AES-GCM must
489           not specify an authentication algorithm. However, for IKE it does
490           require a PRF function, so the second argument to an AEAD algorithm
491           denotes the PRF. So ike=aes_gcm-sha2 means propose AES_GCM with
492           SHA2 as the prf. Note that for phase2alg, there is no prf, so
493           AES-GCM is specified for ESP as esp=aes_gcm-null. The AES-GCM and
494           AES-CCM algorithms support 8,12 and 16 byte ICV's. These can be
495           specified using a postfix, for example aes_gcm_a (for 8), aes_gcm_b
496           (for 12) and aes_gcm_c (for 16). The default (aes_gcm without
497           postfix) refers to the 16 byte ICV version. It is strongly
498           recommended to NOT use the 8 or 12 byte versions of GCM or CCM.
499           These versions are NOT included in the default and will be removed
500           in a future version, following the recommendation of RFC 8247 or it
501           successor.
502
503           Weak algorithms are regularly removed from libreswan. Currently,
504           1DES and modp768(DH1) have been removed and modp1024(DH2) has been
505           disabled at compile time. Additionally, MD5 and SHA1 will be
506           removed within the next few years. Null encryption is available,
507           and should only be used for testing or benchmarking purposes.
508           Please do not request for insecure algorithms to be re-added to
509           libreswan. IKEv1 has been disabled per default, and will soon no
510           longer be compiled in by default.
511
512           For all Diffie-Hellman groups, the "dh" keyword can be used instead
513           of the "modp" keyword. For example ike=3des-sha1;dh19.
514           Diffie-Hellman groups 19,20 and 21 from RFC-5903 are supported.
515           Curve25519 from RFC-8031 is supported as "dh31". Curve448 and GOST
516           DH groups are not yet supported in libreswan because these are not
517           supported yet in the NSS crypto library.
518
519           Diffie-Hellman groups 22, 23 and 24 from RFC-5114 are implemented
520           but not compiled in by default. These DH groups are extremely
521           controversial and MUST NOT be used unless forced (administratively)
522           by the other party. This is further documented in RFC 8247, but the
523           summary is that it cannot be proven that these DH groups do not
524           contain a cryptographic trapdoor (a backdoor by the USG who
525           provided these primes without revealing the seeds and generation
526           process used).
527
528           The modp syntax will be removed in favour of the dh syntax in the
529           future
530
531       phase2
532           Sets the type of SA that will be produced. Valid options are: esp
533           for encryption (the default), ah for authentication only.
534
535           The very first IPsec designs called for use of AH plus ESP to offer
536           authentication, integrity and confidentiality. That dual protocol
537           use was a significant burden, so ESP was extended to offer all
538           three services, and AH remained as an auth/integ. The old mode of
539           ah+esp is no longer supported in compliance with RFC 8221 Section
540           4. Additionally, AH does not play well with NATs, so it is strongly
541           recommended to use ESP with the null cipher if you require
542           unencrypted authenticated transport.
543
544       phase2alg
545           This option is alias to esp.
546
547       sha2-truncbug
548           The default ESP hash truncation for sha2_256 is 128 bits. Some
549           IPsec implementations (Linux before 2.6.33, some Cisco (2811?)
550           routers) implement the draft version which stated 96 bits. If a
551           draft implementation communicates with an RFC implementation, both
552           ends will reject encrypted packets from each other.
553
554           This option enables using the draft 96 bits version to interop with
555           those implementations. Currently the accepted values are no, (the
556           default) signifying default RFC truncation of 128 bits, or yes,
557           signifying the draft 96 bits truncation.
558
559           Another workaround is to switch from sha2_256 to sha2_128 or
560           sha2_512.
561
562       ms-dh-downgrade
563           Whether to allow a downgrade of DiffieHellman group during rekey
564           (using CREATE_CHILD_SA). Microsoft Windows (at the time of writing,
565           Feb 2018) defaults to using the very weak modp1024 (DH2). This can
566           be changed using a Windows registry setting to use modp2048 (DH14).
567           However, at rekey times, it will shamelessly use modp1024 again and
568           the connection might fail. Setting this option to yes (and adding
569           modp1024 proposals to the ike line) this will allow this downgrade
570           attack to happen. This should only be used to support Windows that
571           feature this bug. Currently the accepted values are no, (the
572           default) or yes.
573
574       dns-match-id
575           Whether to perform an additional DNS lookup and confirm the remote
576           ID payload with the DNS name in the reverse DNS PTR record.
577           Accepted values are no (the default) or yes. This check should be
578           enabled when Opportunistic IPsec is enabled in a mode that is based
579           on packet triggers (on-demand) using IPSECKEY records in DNS. Since
580           in that case the IKE daemon pluto does not know the remote ID, it
581           only knows the remote IP address, this option forces it to confirm
582           the peer's proposed ID (and thus its public/private key) with its
583           actual IP address as listed in the DNS. This prevents attacks where
584           mail.example.com's IP address is taken over by a neighbour machine
585           with a valid web.example.com setup. This check is not needed for
586           certificate based Opportunistic IPsec, as "mail.example.com"s
587           certificate does not have an entry for "web.example.com". It is
588           also not needed for DNS server triggered Opportunistic IPsec, as in
589           that case the IKE daemon pluto is informed of both the IP address,
590           and the hostname/public key.
591
592       require-id-on-certificate
593           When using certificates, check whether the IKE peer ID is present
594           as a subjectAltName (SAN) on the peer certificate. Accepted values
595           are yes (the default) or no. This check should only be disabled
596           when intentionally using certificates that do not have their peer
597           ID specified as a SAN on the certificate. These certificates
598           violate RFC 4945 Section 3.1 and are normally rejected to prevent a
599           compromised host from assuming the IKE identity of another host.
600           The SAN limits the IDs that the peer is able to assume.
601
602       ppk
603           EXPERIMENTAL: Post-quantum preshared keys (PPKs) to be used.
604           Currently the accepted values are propose or yes (the default),
605           signifying we propose to use PPK for this connection; insist,
606           signifying we allow communication only if PPK is used for key
607           derivation; never or no, signifying that PPK should not be used for
608           key derivation. PPKs can be used in connections that allow only
609           IKEv2. In libreswan that would mean that ikev2 option must have
610           value insist. (currently based on draft-fluhrer-qr-ikev2, not
611           raft-ietf-ipsecme-qr-ikev2-00)
612
613       nat-ikev1-method
614           NAT Traversal in IKEv1 is negotiated via Vendor ID options as
615           specified in RFC 3947. However, many implementations only support
616           the draft version of the RFC. Libreswan sends both the RFC and the
617           most common draft versions (02, 02_n and 03) to maximize
618           interoperability. Unfortunately, there are known broken
619           implementations of RFC 3947, notably Cisco routers that have not
620           been updated to the latest firmware. As the NAT-T payload is sent
621           in the very first packet of the initiator, there is no method to
622           auto-detect this problem and initiate a workaround.
623
624           This option allows fine tuning which of the NAT-T payloads to
625           consider for sending and processing. Currently the accepted values
626           are drafts, rfc, both (the default) and none. To interoperate with
627           known broken devices, use nat-ikev1-method=drafts. To prevent the
628           other end from triggering IKEv1 NAT-T encapsulation, set this to
629           none. This will omit the NAT-T payloads used to determine NAT,
630           forcing the other end not to use encapsulation.
631
632       esp
633           Specifies the algorithms that will be offered/accepted when
634           negotiating a a Child SA. The general syntax is:
635
636                    ESP = PROPOSAL[,PROPOSAL...]
637                    PROPOSAL = ENCRYPT_ALGS[-INTEG_ALGS[-DH_ALGS]]
638                    ENCRYPT_ALGS = ENCRYPT_ALG[+ENCRYPT_ALG...]
639                    INTEG_ALGS = INTEG_ALG[+INTEG_ALG...]
640                    DH_ALGS = DH_ALG[+DH_ALG...]
641
642
643           During startup, ipsec_pluto(8) will log all supported ESP
644           algorithms.
645
646           Specifying the DH algorithms explicitly is not recommended. When
647           PFS is enabled, and the DH algorithms are omitted, each PROPOSAL
648           will automatically include the DH algorithm negotiated during the
649           IKE exchange.
650
651           AEAD algorithms such as AES_GCM and AES_CCM no not require a
652           separate integrity algorithm. For example esp=aes_gcm256 or
653           esp=aes_ccm.
654
655           For instance:
656
657                    esp=aes_gcm,aes128+aes256-sha2_512+sha2_256-dh14+dh19
658                    esp=aes128-sha2_512-dh14+dh19
659
660
661           If not specified, a secure set of defaults will be used. The
662           program:
663
664                    ipsec algparse esp=...
665
666
667           can be used to query these defaults.
668
669       ah
670           A comma separated list of AH algorithms that will be
671           offered/accepted when negotiating the Child SA. The general syntax
672           is:
673
674                    AH = PROPOSAL[,PROPOSAL...]
675                    PROPOSAL = INTEG_ALGS[-DH_ALGS]
676                    INTEG_ALGS = INTEG_ALG[+INTEG_ALG...]
677                    DH_ALGS = DH_ALG[+DH_ALG...]
678
679
680           During startup, ipsec_pluto(8) will log all supported AH
681           algorithms.
682
683           Specifying the DH algorithms explicitly is not recommended. When
684           PFS is enabled, and the DH algorithms are omitted, each PROPOSAL
685           will automatically include the DH algorithm negotiated during the
686           IKE exchange.
687
688           The default is not to use AH. If for some (invalid) reason you
689           still think you need AH, please use esp with the null encryption
690           cipher instead.
691
692           For instance:
693
694                    ah=sha2_256+sha2_512
695                    ah=sha2_256+sha2_512-dh14+dh19
696
697
698           If not specified, a secure set of defaults will be used. The
699           program:
700
701                    ipsec algparse ah=...
702
703
704           can be used to query these defaults.
705
706       fragmentation
707           Whether or not to allow IKE fragmentation. Valid values are yes,
708           (the default), no or force.
709
710           IKEv1 fragmentation capabilities are negotiated via a well-known
711           private vendor id. IKEv2 fragmentation support is implemented using
712           RFC 7383. If pluto does not receive the fragmentation payload, no
713           IKE fragments will be sent, regardless of the fragmentation=
714           setting. When set to yes, IKE fragmentation will be attempted on
715           the first re-transmit of an IKE packet of a size larger then 576
716           bytes for IPv4 and 1280 bytes for IPv6. If fragmentation is set to
717           force, IKE fragmentation is used on initial transmits of such sized
718           packets as well. When we have received IKE fragments for a
719           connection, pluto behaves as if in force mode.
720
721       ikepad
722           Whether or not to pad IKEv1 messages to a multiple of 4 bytes.
723           Valid values are yes, (the default) and no.
724
725           IKE padding is allowed in IKEv1 but has been known to cause
726           interoperability issues. The ikepad= option can be used to disable
727           IKEv1 padding. This used to be required for some devices (such as
728           Checkpoint in Aggressive Mode) that reject padded IKEv1 packets. A
729           bug was fixed in libreswan 3.25 that applied wrong IKE padding in
730           XAUTH, so it is suspected that Checkpoint padding issue bas been
731           resolved. And this option should not be needed by anyone. In IKEv2,
732           no padding is allowed, and this option has no effect. If you find a
733           device that seems to require IKE padding, please contact the
734           libreswan developers. This option should almost never be enabled
735           and might be removed in a future version.
736
737       ikev2
738           Whether to use IKEv2 (RFC 7296) or IKEv1 (RFC 4301). Currently the
739           accepted values are yes (the default), signifying only IKEv2 is
740           accepted, or no, signifying only IKEv1 is accepted. Previous
741           versions allowed the keywords propose or permit that would allow
742           either IKEv1 or IKEv2, but this is no longer supported. The permit
743           option is interpreted as no and the propose option is interpreted
744           as yes. Older versions also supported keyword insist which is now
745           interpreted as yes.
746
747       mobike
748           Whether to allow MOBIKE (RFC 4555) to enable a connection to
749           migrate its endpoint without needing to restart the connection from
750           scratch. This is used on mobile devices that switch between wired,
751           wireless or mobile data connections. Current values are no (the
752           default) or yes, Only connection acting as modecfgclient will allow
753           the initiator to migrate using mobike. Only connections acting as
754           modecfgserver will allow clients to migrate.
755
756           VTI and MOBIKE might not work well when used together.
757
758       esn
759           Whether or not to enable Extended Sequence Number (ESN) for the
760           IPsec SA. This option is only implemented for IKEv2. ESN is
761           typically used for very high-speed links (10Gbps or faster) where
762           the standard 32 bit sequence number is exhausted too quickly,
763           causing IPsec SA's rekeys to happen too often. Accepted values are
764           either (the default), yes and no. If either is specified as an
765           initiator, the responder will make the choice. As a responder, if
766           either is received, yes is picked.
767
768           If replay-window is set to 0, ESN is disabled as some (most?) IPsec
769           stacks won't support ESN in such a configuration.
770
771       decap-dscp
772           Enable decapsulating the Differentiated Services Code Point (DSCP,
773           formerly known as Terms Of Service (TOS)) bits. If these bits are
774           set on the inner (encrypted) IP packets, these bits are set on the
775           decrypted IP packets. Acceptable values are no (the default) or
776           yes. Currently this feature is only implemented for the Linux XFRM
777           stack.
778
779       nopmtudisc
780           Disable Path MTU discovery for the IPsec SA. Acceptable values are
781           no (the default) or yes. Currently this feature is only implemented
782           for the Linux XFRM stack.
783
784       narrowing
785           IKEv2 (RFC5996) Section 2.9 Traffic Selector narrowing options.
786           Currently the accepted values are no, (the default) signifying no
787           narrowing will be proposed or accepted, or yes, signifying IKEv2
788           negotiation may allow establishing an IPsec connection with
789           narrowed down traffic selectors. This option is ignored for IKEv1.
790
791           There are security implications in allowing narrowing down the
792           proposal. For one, what should be done with packets that we hoped
793           to tunnel, but cannot. Should these be dropped or send in the
794           clear? Second, this could cause thousands of narrowed down Child
795           SAs to be created if the conn has a broad policy (eg 0/0 to 0/0).
796           One possible good use case scenario is that a remote end (that you
797           fully trust) allows you to define a 0/0 to them, while adjusting
798           what traffic you route via them, and what traffic remains outside
799           the tunnel. However, it is always preferred to setup the exact
800           tunnel policy you want, as this will be much clearer to the user.
801
802       sareftrack
803           Set the method of tracking reply packets with SArefs when using an
804           SAref compatible stack. Currently only the mast stack supports
805           this. Acceptable values are yes (the default), no or conntrack.
806           This option is ignored when SArefs are not supported. This option
807           is passed as PLUTO_SAREF_TRACKING to the updown script which makes
808           the actual decisions whether to perform any iptables/ip_conntrack
809           manipulation. A value of yes means that an IPSEC mangle table will
810           be created. This table will be used to match reply packets. A value
811           of conntrack means that additionally, subsequent packets using this
812           connection will be marked as well, reducing the lookups needed to
813           find the proper SAref by using the ip_conntrack state. A value of
814           no means no IPSEC mangle table is created, and SAref tracking is
815           left to a third-party (kernel) module. In case of a third party
816           module, the SArefs can be relayed using the statsbin= notification
817           helper.
818
819       nic-offload
820           Set the method of Network Interface Controller (NIC) hardware
821           offload for ESP/AH packet processing. Acceptable values are auto
822           (the default), yes or no. This option is separate from any CPU
823           hardware offload available and is currently only available on Linux
824           4.13+ using the XFRM IPsec stack, when compiled with the options
825           CONFIG_XFRM_OFFLOAD, CONFIG_INET_ESP_OFFLOAD and
826           CONFIG_INET6_ESP_OFFLOAD. The auto option will attempt to
827           auto-detect the presence of kernel and hardware support, and then
828           automatically mark the IPsec SA for hardware offloading. One vendor
829           supporting this offload method is Mellanox.
830
831       leftid
832           how the left participant should be identified for authentication;
833           defaults to left. Can be an IP address or a fully-qualified domain
834           name which will be resolved. If preceded by @, the value is used as
835           a literal string and will not be resolved. To support opaque
836           identifiers (usually of type ID_KEY_ID, such as used by Cisco to
837           specify Group Name, use square brackets, eg rightid=@[GroupName].
838           The magic value %fromcert causes the ID to be set to a DN taken
839           from a certificate that is loaded. Prior to 2.5.16, this was the
840           default if a certificate was specified. The magic value %none sets
841           the ID to no ID. This is included for completeness, as the ID may
842           have been set in the default conn, and one wishes for it to default
843           instead of being explicitly set. The magic value %myid stands for
844           the current setting of myid. This is set in config setup or by
845           ipsec_whack(8)), or, if not set, it is the IP address in
846           %defaultroute (if that is supported by a TXT record in its reverse
847           domain), or otherwise it is the system's hostname (if that is
848           supported by a TXT record in its forward domain), or otherwise it
849           is undefined.
850
851           When using certificate based ID's, one need to specify the full
852           RDN, optionally using wildcard matching (eg CN='*'). If the RDN
853           contains a comma, this can be masked using a comma (eg OU='Foo,,
854           Bar and associates')
855
856       leftrsasigkey
857           the left participant's public key for RSA signature authentication,
858           in RFC 2537 format using ipsec_ttodata(3) encoding. The magic value
859           %none means the same as not specifying a value (useful to override
860           a default). The value %dnsondemand (the default) means the key is
861           to be fetched from DNS at the time it is needed. The value
862           %dnsonload means the key is to be fetched from DNS at the time the
863           connection description is read from ipsec.conf; currently this will
864           be treated as %none if right=%any or right=%opportunistic. The
865           value %dns is currently treated as %dnsonload but will change to
866           %dnsondemand in the future. The identity used for the left
867           participant must be a specific host, not %any or another magic
868           value. The value %cert will load the information required from a
869           certificate defined in %leftcert and automatically define leftid
870           for you.  Caution: if two connection descriptions specify different
871           public keys for the same leftid, confusion and madness will ensue.
872
873       leftcert
874           If you are using leftrsasigkey=%cert this defines the certificate
875           nickname of your certificate in the NSS database. This can be on
876           software or hardware security device.
877
878       leftckaid
879           The hex CKAID of the X.509 certificate. Certificates are stored in
880           the NSS database.
881
882       leftauth
883           How the security gateways will authenticate to the other side in
884           the case of asymmetric authentication; acceptable values are rsasig
885           or rsa for RSA Authentication with SHA-1, rsa-sha2 for RSA-PSS
886           digital signatures based authentication with SHA2-256, rsa-sha2_384
887           for RSA-PSS digital signatures based authentication with SHA2-384,
888           rsa-sha2_512 for RSA-PSS digital signatures based authentication
889           with SHA2-512, ecdsa for ECDSA digital signatures based
890           authentication, secret for shared secrets (PSK) authentication and
891           null for null-authentication. There is no default value - if unset,
892           the symmetrical authby= keyword is used to determine the
893           authentication policy of the connection.
894
895           Asymmetric authentication is only supported with IKEv2. If
896           symmetric authentication is required, use authby= instead of
897           leftauth and rightauth. If leftauth is set, rightauth must also be
898           set and authby= must not be set. Asymmetric authentication cannot
899           use secret (psk) on one side and null on the other side - use psk
900           on both ends instead.
901
902           When using EAPONLY authentication, which omits the regular IKEv2
903           AUTH payload, leftauth= (or rightauth=) should be set to eaponly.
904
905           Be aware that the symmetric keyword is authby= but the asymmetric
906           keyword is leftauth and rightauth (without the "by").
907
908       leftautheap
909           Whether the security gateways will authenticate uing an EAP method.
910           Acceptable values are none (the default) and tls for EAPTLS. If EAP
911           is the only authentication method, set leftauth=none in addition to
912           leftautheap=tls=.
913
914           The EAP authentication mechanisms are only available for IKEv2
915           based connections.
916
917       leftca
918           specifies the authorized Certificate Authority (CA) that signed the
919           certificate of the peer. If undefined, it defaults to the CA that
920           signed the certificate specified in leftcert. The special
921           rightca=%same is implied when not specifying a rightca and means
922           that only peers with certificates signed by the same CA as the
923           leftca will be allowed. This option is only useful in complex multi
924           CA certificate situations. When using a single CA, it can be safely
925           omitted for both left and right.
926
927       leftikeport
928           The UDP IKE port to listen on or send data to. This port cannot be
929           0 or 500. For TCP, see tcp-remoteport=
930
931       leftsendcert
932           This option configures when Libreswan will send X.509 certificates
933           to the remote host. Acceptable values are yes|always (signifying
934           that we should always send a certificate), sendifasked (signifying
935           that we should send a certificate if the remote end asks for it),
936           and no|never (signifying that we will never send a X.509
937           certificate). The default for this option is sendifasked which may
938           break compatibility with other vendor's IPsec implementations, such
939           as Cisco and SafeNet. If you find that you are getting errors about
940           no ID/Key found, you likely need to set this to always. This
941           per-conn option replaces the obsolete global nocrsend option.
942
943       leftxauthserver
944           Left is an XAUTH server. This can use PAM for authentication or md5
945           passwords in /etc/ipsec.d/passwd. These are additional credentials
946           to verify the user identity, and should not be confused with the
947           XAUTH group secret, which is just a regular PSK defined in
948           ipsec.secrets. The other side of the connection should be
949           configured as rightxauthclient. XAUTH connections cannot rekey, so
950           rekey=no should be specified in this conn. For further details on
951           how to compile and use XAUTH, see README.XAUTH. Acceptable values
952           are yes or no (the default).
953
954       leftxauthclient
955           Left is an XAUTH client. The xauth connection will have to be
956           started interactively and cannot be configured using auto=start.
957           Instead, it has to be started from the commandline using ipsec auto
958           --up connname. You will then be prompted for the username and
959           password. To setup an XAUTH connection non-interactively, which
960           defeats the whole purpose of XAUTH, but is regularly requested by
961           users, it is possible to use a whack command - ipsec whack --name
962           baduser --ipsecgroup-xauth --xauthname badusername --xauthpass
963           password --initiate The other side of the connection should be
964           configured as rightxauthserver. Acceptable values are yes or no
965           (the default).
966
967       leftusername
968           The username associated with this connection. The username can be
969           the IKEv2 XAUTH username, a GSSAPI username or IKEv2 CP username.
970           For the XAUTH username, the XAUTH password can be configured in the
971           ipsec.secrets file. This option was previously called
972           leftxauthusername.
973
974       leftmodecfgserver
975           Left is a Mode Config server. It can push network configuration to
976           the client. Acceptable values are yes or no (the default).
977
978       leftmodecfgclient
979           Left is a Mode Config client. It can receive network configuration
980           from the server. Acceptable values are yes or no (the default).
981
982       xauthby
983           When IKEv1 XAUTH support is available, set the method used by XAUTH
984           to authenticate the user with IKEv1. The currently supported values
985           are file (the default), pam or alwaysok. The password file is
986           located at /etc/ipsec.d/passwd, and follows a syntax similar to the
987           Apache htpasswd file, except an additional connection name argument
988           (and optional static IP address) are also present:
989
990                 username:password:conname:ipaddress
991
992           For supported password hashing methods, see crypt(3). If pluto is
993           running in FIPS mode, some hash methods, such as MD5, might not be
994           available. Threads are used to launch an xauth authentication
995           helper for file as well as PAM methods.
996
997           The alwaysok should only be used if the XAUTH user authentication
998           is not really used, but is required for interoperability, as it
999           defeats the whole point of XAUTH which is to rely on a secret only
1000           known by a human. See also pam-authorize=yes
1001
1002       xauthfail
1003           When XAUTH support is available, set the failure method desired
1004           when authentication has failed. The currently supported values are
1005           hard (the default) and soft. A soft failure means the IPsec SA is
1006           allowed to be established, as if authentication had passed
1007           successfully, but the XAUTH_FAILED environment variable will be set
1008           to 1 for the updown script, which can then be used to redirect the
1009           user into a walled garden, for example a payment portal.
1010
1011       pam-authorize
1012           IKEv1 supports PAM authorization via XAUTH using xauthby=pam. IKEv2
1013           does not support receiving a plaintext username and password.
1014           Libreswan does not yet support EAP authentication methods for IKE.
1015           The pam-authorize=yes option performs an authorization call via
1016           PAM, but only includes the remote ID (not username or password).
1017           This allows for backends to disallow an ID based on non-password
1018           situations, such as "user disabled" or "user over quota". See also
1019           xauthby=pam
1020
1021       modecfgpull
1022           Pull the Mode Config network information from the server.
1023           Acceptable values are yes or no (the default).
1024
1025       modecfgdns, modecfgdomains, modecfgbanner
1026           When configured as IKEv1 ModeCFG or IKEv2 server, specifying any of
1027           these options will cause those options and values to be sent to the
1028           connecting client. Libreswan as a client will use these received
1029           options to either update /etc/resolv.conf or the running unbound
1030           DNS server. When the connection is brought down, the previous DNS
1031           resolving state is restored.
1032
1033           The modecfgdns option takes a comma or space separated list of IP
1034           addresses that can be used for DNS resolution. The modecfgdomains
1035           option takes a comma or space separated list of internal domain
1036           names that are reachable via the supplied modecfgdns DNS servers.
1037
1038           The IKEv1 split tunnel directive will be sent automatically if the
1039           xauth server side has configured a network other than 0.0.0.0/0.
1040           For IKEv2, this is automated via narrowing.
1041
1042       remote-peer-type
1043           Set the remote peer type. This can enable additional processing
1044           during the IKE negotiation. Acceptable values are cisco or ietf
1045           (the default). When set to cisco, support for Cisco IPsec gateway
1046           redirection and Cisco obtained DNS and domainname are enabled. This
1047           includes automatically updating (and restoring) /etc/resolv.conf.
1048           These options require that XAUTH is also enabled on this
1049           connection.
1050
1051       nm-configured
1052           Mark this connection as controlled by Network Manager. Acceptable
1053           values are yes or no (the default). Currently, setting this to yes
1054           will cause libreswan to skip reconfiguring resolv.conf when used
1055           with XAUTH and ModeConfig.
1056
1057       encapsulation
1058           In some cases, for example when ESP packets are filtered or when a
1059           broken IPsec peer does not properly recognise NAT, it can be useful
1060           to force RFC-3948 encapsulation. In other cases, where IKE is
1061           NAT'ed but ESP packets can or should flow without encapsulation, it
1062           can be useful to ignore the NAT-Traversal auto-detection.
1063           encapsulation=yes forces the NAT detection code to lie and tell the
1064           remote peer that RFC-3948 encapsulation (ESP in port 4500 packets)
1065           is required.  encapsulation=no ignores the NAT detection causing
1066           ESP packets to send send without encapsulation. The default value
1067           of encapsulation=auto follows the regular outcome of the NAT
1068           auto-detection code performed in IKE. This option replaced the
1069           obsoleted forceencaps option.
1070
1071       enable-tcp
1072           Normally, IKE negotiation and ESP encapsulation happens over UDP.
1073           This option enables support for IKE and ESP over TCP as per RFC
1074           8229. Acceptable values are no(the default), yes meaning only TCP
1075           will be used, or fallback meaning that TCP will be attempted only
1076           after negotiation over UDP failed. Since performance over TCP is
1077           much less, and TCP sessions are vulnerable to simply RST resets and
1078           MITM attacks causing the TCP connection to close, this option
1079           should really only be used in fallback mode. If used in fallback
1080           mode, it is recommend to reduce the retransmit-timeout from the
1081           default 60s to a much shorter value such as 10s, so that one does
1082           not have to wait a minute for the TCP fallback to be attempted.
1083
1084       tcp-remoteport
1085           Which remote TCP port to use when IKE over TCP is attempted. The
1086           default value is to use the NAT-T IKE port (4500). This value is
1087           not negotiated and should be configured properly on all endpoints.
1088           When opening a TCP socket to the remote host in this port, a
1089           regular ephemeral source port is obtained from the OS. For changing
1090           the UDP ports, see leftikeport=
1091
1092       nat-keepalive
1093           whether to send any NAT-T keep-alives. These one byte packets are
1094           send to prevent the NAT router from closing its port when there is
1095           not enough traffic on the IPsec connection. Acceptable values are:
1096           yes (the default) and no.
1097
1098       initial-contact
1099           whether to send an INITIAL_CONTACT payload to the peer we are
1100           initiating to, if we currently have no IPsec SAs up with that peer.
1101           Acceptable values are: yes (the default) and no. It is recommended
1102           to leave this option set, unless multiple clients with the same
1103           identity are expected to connect using the same subnets and should
1104           operate at the same time. Or if a reconnecting client should not
1105           delete its old instance (eg perhaps it is still running). This is
1106           unlikely to be true.
1107
1108       cisco-unity
1109           whether to send a CISCO_UNITY payload to the peer. Acceptable
1110           values are: no (the default) and yes. It is recommended to leave
1111           this option unset, unless the remote peer (Cisco client or server)
1112           requires it. This option does not modify local behaviour. It can be
1113           needed to connect as a client to a Cisco server. It can also be
1114           needed to act as a server for a Cisco client, which otherwise might
1115           send back an error DEL_REASON_NON_UNITY_PEER.
1116
1117       ignore-peer-dns
1118           whether to ignore received DNS configuration. Acceptable values
1119           are: no (the default) and yes. Normally, when a roadwarrior
1120           connects to a remote VPN, the remote VPN server sends a list of DNS
1121           domains and DNS nameserver IP addresses that the roadwarrior can
1122           use to reach internal only resources through the VPN. This option
1123           allows the roadwarrior to ignore the server's suggestion. The
1124           roadwarrior will normally use this information to update the DNS
1125           resolving process. What is changed depends on the detected DNS
1126           configuration. It can modify /etc/resolv.conf directly, or
1127           reconfigure a locally running DNS server (unbound, knot, stubby or
1128           systemd-resolved) or inform NetworkManager.
1129
1130       accept-redirect
1131           Whether requests of the remote peer to redirect IKE/IPsec SA's are
1132           accepted. Valid options are no (the default) and yes. See also
1133           accept-redirect-to.
1134
1135       accept-redirect-to
1136           Specify the comma separated list of addresses we accept being
1137           redirected to. Both IPv4 and IPv6 addresses are supported as well
1138           the FQDNs. The value %any, as well as not specifying any address,
1139           signifes that we will redirect to any address gateway sends us in
1140           REDIRECT notify payload.
1141
1142           The value of this option is not considered at all if
1143           accept-redirect is set to no.
1144
1145       send-redirect
1146           Whether to send requests for the remote peer to redirect IKE/IPsec
1147           SA's during IKE_AUTH. Valid options are no (the default) and yes.
1148           If set, the option redirect-to= must also be set to indicate where
1149           to redirect peers to. For redirection during IKE_SA_INIT exchange,
1150           see the global-redirect= and global-redirect-to= options. Runtime
1151           redirects can be triggered via the ipsec whack --redirect command.
1152
1153       redirect-to
1154           Where to send remote peers to via the send-redirect option. This
1155           can be an IP address or hostname (FQDN).
1156
1157       fake-strongswan
1158           whether to send a STRONGSWAN Vendor ID payload to the peer.
1159           Acceptable values are: no (the default) and yes. This used to be
1160           required because strongswan rejects certain proposals with private
1161           use numbers such as esp=twofish or esp=serpent unless it receives a
1162           strongswan vendorid by the peer. This option sends such an
1163           (unversioned) vendor id. Note that libreswan and strongswan no
1164           longer support twofish or serpent, so enabling this option likely
1165           will no longer do anything.
1166
1167       send-vendorid
1168           whether to send our Vendor ID during IKE. Acceptable values are: no
1169           (the default) and yes. The vendor id sent can be configured using
1170           the "config setup" option myvendorid=. It defaults to
1171           OE-Libreswan-VERSION.
1172
1173           Vendor ID's can be useful in tracking interoperability problems.
1174           However, specific vendor identification and software versions can
1175           be useful to an attacker when there are known vulnerabilities to a
1176           specific vendor/version.
1177
1178           The prefix OE stands for "Opportunistic Encryption". This prefix
1179           was historically used by The FreeS/WAN Project and The Openswan
1180           Project (openswan up to version 2.6.38) and in one Xeleranized
1181           openswan versions (2.6.39). Further Xeleranized openswan's use the
1182           prefix OSW.
1183
1184       overlapip
1185           a boolean (yes/no) that determines, when (left|right)subnet=vhost:
1186           is used, if the virtual IP claimed by this states created from this
1187           connection can with states created from other connections.
1188
1189           Note that connection instances created by the Opportunistic
1190           Encryption or PKIX (x.509) instantiation system are distinct
1191           internally. They will inherit this policy bit.
1192
1193           The default is no.
1194
1195           This feature is only available with kernel drivers that support SAs
1196           to overlapping conns. At present only the (klips) mast protocol
1197           stack supports this feature.
1198
1199       reqid
1200           a unique identifier used to match IPsec SAs using iptables with
1201           XFRM. This identifier is normally automatically allocated in groups
1202           of 4. It is exported to the _updown script as REQID. On Linux,
1203           reqids are supported with IP Connection Tracking and NAT
1204           (iptables). Automatically generated values use the range 16380 and
1205           higher. Manually specified reqid values therefore must be between 1
1206           and 16379.
1207
1208           Automatically generated reqids use a range of 0-3 (eg 16380-16383
1209           for the first reqid). These are used depending on the exact policy
1210           (AH, AH+ESP, IPCOMP, etc).
1211
1212           WARNING: Manually assigned reqids are all identical. Instantiations
1213           of connections (those using %any wildcards) will all use the same
1214           reqid. If you use manual assigning you should make sure your
1215           connections only match single road warrior only or you break
1216           multiple road warriors behind same NAT router because this feature
1217           requires unique reqids to work.
1218
1219       dpddelay
1220           Set the delay (in time units, defaults to seconds) between Dead
1221           Peer Detection (IKEv1 RFC 3706) or IKEv2 Liveness keepalives that
1222           are sent for this connection (default 0 seconds). Set to enable
1223           checking. If dpddelay is set, dpdtimeout also needs to be set.
1224
1225       dpdtimeout
1226           Set the length of time (in time units, defaults to seconds) that we
1227           will idle without hearing back from our peer. After this period has
1228           elapsed with no response and no traffic, we will declare the peer
1229           dead, and remove the SA (default 0 seconds). Set value bigger than
1230           dpddelay to enable. If dpdtimeout is set, dpddelay also needs to be
1231           set.
1232
1233       dpdaction
1234           When a DPD enabled peer is declared dead, what action should be
1235           taken.  hold (default) means the eroute will be put into %hold
1236           status, while clear means the eroute and SA with both be cleared.
1237           restart means that ALL SAs to the dead peer will renegotiated.
1238
1239           dpdaction=clear is really only useful on the server of a Road
1240           Warrior config.
1241
1242           The value restart_by_peer has been obsoleted and its functionality
1243           moved into the regular restart action.
1244
1245       pfs
1246           whether Perfect Forward Secrecy of keys is desired on the
1247           connection's keying channel (with PFS, penetration of the
1248           key-exchange protocol does not compromise keys negotiated earlier);
1249           Acceptable values are yes (the default) and no.
1250
1251       pfsgroup
1252           This option is obsoleted, please use phase2alg if you need the PFS
1253           to be different from phase1 (the default) using:
1254           phase2alg=aes128-md5;modp1024
1255
1256       aggressive
1257           Use IKEv1 Aggressive Mode instead of IKEv1 Main Mode. This option
1258           has no effect when IKEv2 is used. Acceptable values are no (the
1259           default) or yes. When this option is enabled, IKEv1 Main Mode will
1260           no longer be allowed for this connection. The old name of this
1261           option was aggrmode.
1262
1263           Aggressive Mode is less secure, and more vulnerable to Denial Of
1264           Service attacks. It is also vulnerable to brute force attacks with
1265           software such as ikecrack. It should not be used, and it should
1266           especially not be used with XAUTH and group secrets (PSK). If the
1267           remote system administrator insists on staying irresponsible,
1268           enable this option.
1269
1270           Aggressive Mode is further limited to only proposals with one DH
1271           group as there is no room to negotiate the DH group. Therefore it
1272           is mandatory for Aggressive Mode connections that both ike= and
1273           phase2alg= options are specified with only one fully specified
1274           proposal using one DH group.
1275
1276           The KE payload is created in the first exchange packet when using
1277           aggressive mode. The KE payload depends on the DH group used. This
1278           is why there cannot be multiple DH groups in IKEv1 aggressive mode.
1279           In IKEv2, which uses a similar method to IKEv1 Aggressive Mode,
1280           there is an INVALID_KE response payload that can inform the
1281           initiator of the responder's desired DH group and so an IKEv2
1282           connection can actually recover from picking the wrong DH group by
1283           restarting its negotiation.
1284
1285       salifetime
1286           how long a particular instance of a connection (a set of
1287           encryption/authentication keys for user packets) should last, from
1288           successful negotiation to expiry; acceptable values are an integer
1289           optionally followed by s (a time in seconds) or a decimal number
1290           followed by m, h, or d (a time in minutes, hours, or days
1291           respectively) (default 8h, maximum 24h). Normally, the connection
1292           is renegotiated (via the keying channel) before it expires. The two
1293           ends need not exactly agree on salifetime, although if they do not,
1294           there will be some clutter of superseded connections on the end
1295           which thinks the lifetime is longer.
1296
1297           The keywords "keylife" and "lifetime" are obsoleted aliases for
1298           "salifetime." Change your configs to use "salifetime" instead.
1299
1300       replay-window
1301           The size of the IPsec SA replay window protection. The default is
1302           128. Linux XFRM allows at least up to 2048. A value of of 0
1303           disables replay protection. Disabling of replay protection is
1304           sometimes used on a pair of IPsec servers in a High Availability
1305           setup, or on servers with very unpredictable latency, such as
1306           mobile networks, which can cause an excessive amount of out of
1307           order packets. Sequence errors can be seen in /proc/net/xfrm_stat.
1308
1309           Setting replay-window to 0 will also disable Extended Sequence
1310           Numbers (esn=no), as advise from RFC 4303 caused some stacks to not
1311           support ESN without a replay-window.
1312
1313           Note that technically, at least the Linux kernel can install IPsec
1314           SA's with an IPsec SA Sequence Number, but this is currently not
1315           supported by libreswan.
1316
1317       rekey
1318           whether a connection should be renegotiated when it is about to
1319           expire; acceptable values are yes (the default) and no. The two
1320           ends need not agree, but while a value of no prevents Pluto from
1321           requesting renegotiation, it does not prevent responding to
1322           renegotiation requested from the other end, so no will be largely
1323           ineffective unless both ends agree on it.
1324
1325       rekeymargin
1326           how long before connection expiry or keying-channel expiry should
1327           attempts to negotiate a replacement begin; acceptable values as for
1328           salifetime (default 9m). Relevant only locally, other end need not
1329           agree on it.
1330
1331       rekeyfuzz
1332           maximum percentage by which rekeymargin should be randomly
1333           increased to randomize rekeying intervals (important for hosts with
1334           many connections); acceptable values are an integer, which may
1335           exceed 100, followed by a `%' (default set by ipsec_pluto(8),
1336           currently 100%). The value of rekeymargin, after this random
1337           increase, must not exceed salifetime. The value 0% will suppress
1338           time randomization. Relevant only locally, other end need not agree
1339           on it.
1340
1341       keyingtries
1342           how many attempts (a whole number or %forever) should be made to
1343           negotiate a connection, or a replacement for one, before giving up
1344           (default %forever). The value %forever or 0 means to keep trying
1345           forever. For Opportunistic Encryption connections, a keyingtries
1346           value of %forever or 0 is set to 1 and a warning message will be
1347           logged. This is because an expired failureshunt triggers new
1348           keyingtries on-demand later, when there is traffic. This prevents
1349           accumulating an infinite amount of attempts to peers that do not
1350           support Opportunistic Encryption. For Opportunistic, a keyingtries
1351           value of > 1 is allowed but currently not recommended. The meaning
1352           of failureshunt= is unclear when there is continued (failed) keying
1353           happening with a negotiationshunt installed. Relevant only locally,
1354           other end need not agree on it.
1355
1356       ikelifetime
1357           how long the keying channel of a connection (buzzphrase: “IKE SA”
1358           or “Parent SA”) should last before being renegotiated; acceptable
1359           values as for salifetime. The default as of version 4.2 is 8h,
1360           before that it was 1h. The maximum is 24h. The two-ends-disagree
1361           case is similar to that of salifetime.
1362
1363       retransmit-timeout
1364           how long a single packet, including retransmits of that packet, may
1365           take before the IKE attempt is aborted. If rekeying is enabled, a
1366           new IKE attempt is started. The default set by ipsec_pluto(8),
1367           currently is 60s. See also: retransmit-interval, rekey and
1368           keyingtries.
1369
1370       retransmit-interval
1371           the initial interval time period, specified in msecs, that pluto
1372           waits before retransmitting an IKE packet. This interval is doubled
1373           for each attempt (exponential back-off). The default set by
1374           ipsec_pluto(8), currently is 500. See also: retransmit-timeout,
1375           rekey and keyingtries.
1376
1377       compress
1378           whether IPComp compression of content is proposed on the connection
1379           (link-level compression does not work on encrypted data, so to be
1380           effective, compression must be done before encryption); acceptable
1381           values are yes and no (the default).
1382
1383           For IKEv1, compress settings on both peers must match. For IKEv2,
1384           compression can only be suggested and a mismatched compress setting
1385           results in connection without compression.
1386
1387           When set to yes, compression is negotiated for the DEFLATE
1388           compression algorithm.
1389
1390       metric
1391           Set the metric for added routes. This value is passed to the
1392           _updown scripts as PLUTO_METRIC. Acceptable values are positive
1393           numbers, with the default being 1.
1394
1395       mtu
1396           Set the MTU for the route(s) to the remote endpoint and/or subnets.
1397           This is sometimes required when the overhead of the IPsec
1398           encapsulation would cause the packet the become too big for a
1399           router on the path. Since IPsec cannot trust any unauthenticated
1400           ICMP messages, PATH MTU discovery does not work. This can also be
1401           needed when using "6to4" IPV6 deployments, which adds another
1402           header on the packet size. Acceptable values are positive numbers.
1403           There is no default.
1404
1405       tfc
1406           Enable Traffic Flow Confidentiality ("TFC") (RFC-4303) for outgoing
1407           ESP packets in Tunnel Mode. When enabled, ESP packets are padded to
1408           the specified size (up to the PMTU size) to prevent leaking
1409           information based on ESP packet size. This option is ignored for AH
1410           and for ESP in Transport Mode as those always leak traffic
1411           characteristics and applying TFC will not do anything. Acceptable
1412           values are positive numbers. The value 0 means TFC padding is not
1413           performed. Currently this feature is only implemented for the Linux
1414           XFRM stack. In IKEv2, when the notify payload
1415           ESP_TFC_PADDING_NOT_SUPPORTED is received, TFC padding is disabled.
1416           The default is not to do any TFC padding, but this might change in
1417           the near future.
1418
1419       send-no-esp-tfc
1420           Whether or not to tell the remote peer that we do not support
1421           Traffic Flow Confidentiality ("TFC") (RFC-4303). Possible values
1422           are no (the default) which allows the peer to use TFC or yes which
1423           prevents to peer from using TFC. This does not affect whether this
1424           endpoint uses TFC, which only depends on the local tfc setting.
1425           This option is only valid for IKEv2.
1426
1427       nflog
1428           If set, the NFLOG group number to log this connection's pre-crypt
1429           and post-decrypt traffic to. The default value of 0 means no
1430           logging at all. This option is only available on linux kernel
1431           2.6.14 and later. It allows common network utilities such as
1432           tcpdump, wireshark and dumpcap, to use nflog:XXX pseudo interfaces
1433           where XXX is the nflog group number. During the updown phase of a
1434           connection, iptables will be used to add and remove the
1435           source/destination pair to the nflog group specified. The rules are
1436           setup with the nflog-prefix matching the connection name. See also
1437           the global nflog-all option.
1438
1439       mark
1440           If set, the MARK to set for the IPsec SA of this connection. The
1441           format of a CONNMARK is mark/mask. If the mask is left out, a
1442           default mask of 0xffffffff is used. A mark value of -1 means to
1443           assign a new global unique mark number for each instance of the
1444           connection. Global marks start at 1001. This option is only
1445           available on linux XFRM kernels. It can be used with iptables to
1446           create custom iptables rules using CONNMARK. It can also be used
1447           with Virtual Tunnel Interfaces ("VTI") to direct marked traffic to
1448           specific vtiXX devices.
1449
1450       mark-in
1451           The same as mark, but mark-in only applies to the inbound half of
1452           the IPsec SA. It overrides any mark= setting.
1453
1454       mark-out
1455           The same as mark, but mark-out only applies to the outbound half of
1456           the IPsec SA. It overrides any mark= setting.
1457
1458       vti-interface
1459           This option is used to create "Routing based VPNs" (as opposed to
1460           "Policy based VPNs"). It will create a new interface that can be
1461           used to route traffic in for encryption/decryption. The Virtual
1462           Tunnel Interface ("VTI") interface name is used to for all IPsec
1463           SA's created by this connection. This requires that the connection
1464           also enables either the mark= or mark-in= / mark-out- option(s).
1465           All traffic marked with the proper MARKs will be automatically
1466           encrypted if there is an IPsec SA policy covering the
1467           source/destination traffic. Tools such as tcpdump and iptables can
1468           be used on all cleartext pre-encrypt and post-decrypt traffic on
1469           the device. See the libreswan wiki for example configurations that
1470           use VTI.
1471
1472           VTI interfaces are currently only supported on Linux with XFRM. The
1473           _updown script handles certain Linux specific interfaces settings
1474           required for proper functioning (disable_policy, rp_filter,
1475           forwarding, etc). Interface names are limited to 16 characters and
1476           may not allow all characters to be used. If marking and
1477           vti-routing=yes is used, no manual iptables should be required.
1478           However, administrators can use the iptables mangle table to mark
1479           traffic manually if desired.
1480
1481       vti-routing
1482           Whether or not to add network rules or routes for IPsec SA's to the
1483           respective VTI devices. Valid values are yes (the default) or no.
1484           When using "routing based VPNs" with a subnets policy of 0.0.0.0/0,
1485           this setting needs to set to no to prevent imploding the tunnel,
1486           and the administrator is expected to manually add ip rules and ip
1487           routes to configure what traffic must be encrypted. When set to
1488           yes, the _updown script will automatically route the
1489           leftsubnet/rightsubnet traffic into the VTI device specified with
1490           vti-interface
1491
1492       vti-shared
1493           Whether or not the VTI device is shared amongst connections. Valid
1494           values are no (the default) or yes. When set to no, the VTI device
1495           is automatically deleted if the connection is a single
1496           non-instantiated connection. If a connection instantiates (eg
1497           right=%any) then this option has no effect, as the VTI device is
1498           not removed as it is shared with multiple roadwarriors.
1499
1500       ipsec-interface
1501           Create or use an existing virtual interface ipsecXXX for "Routing
1502           based VPNs" (as opposed to "Policy based VPNs"). Valid options are
1503           yes, no or a number. When using a number, the IPsec interface
1504           created and/or used will use that number as part of the interface
1505           name. For example setting ipsec-interface=5 will create and/or use
1506           the ipsec5 interface. The value 0 cannot be used and is interpreted
1507           as no. The value yes is interpreted as the number 1, and thus will
1508           use the interface named ipsec1. An IP address can be configured for
1509           this interface via the interface-ip= option.
1510
1511           The ipsec-interface is used to route outbound traffic that needs to
1512           be encrypted, and will decrypt inbound traffic that arrives on this
1513           interface. All traffic that is routed to this interface will be
1514           automatically encrypted providing the IPsec SA policy covers this
1515           traffic. Traffic not matching the IPsec SA will be dropped. Tools
1516           such as tcpdump, iptables, ifconfig and tools that need traffic
1517           counters can be used on all cleartext pre-encrypt and post-decrypt
1518           traffic on the device. When leftsubnet= is equal to rightsubnet=,
1519           the routing needs to be manged by an external routing daemon or
1520           manually by the administrator.
1521
1522           This option is currently only supported on Linux kernels 4.19 or
1523           later when compiled with XFRMi support (CONFIG_XFRM_INTERFACE). The
1524           number of the ipsecX device corresponds with the XFRM IF_ID policy
1525           option of the IPsec SA in the Linux kernel. On Linux, XFRMi
1526           interfaces can be managed by libreswan automatically or can be
1527           preconfigured on the system using the existing init system or via
1528           networking tools such as systemd-networkd and NetworkManager. The
1529           _updown script handles certain Linux specific interfaces settings
1530           required for proper functioning, such as forwarding and routing
1531           rules for IPsec traffic.
1532
1533           The ipsec-interface=0 will create an interface with the same name
1534           as the old KLIPS interface, ipsec0. This interface name should only
1535           be used when required for migration from KLIPS to XFRM interfaces.
1536           Since XFRM IF_ID and marking cannot use 0, this is mapped to 16384.
1537           This means that the devices ipsec0 and ipsec16384 cannot both be in
1538           use.
1539
1540       interface-ip=
1541           NOTE: This option is currently not implemented pending pluto IP
1542           address reference counting. The IP address and netmask to configure
1543           on a virtual device (eg ipsecXXX). This is often used when building
1544           Routing based IPsec tunnels using transport mode and GRE, but can
1545           also be useful in other scenarios. Currently requires
1546           ipsec-interface=. See also leftvti= for cnofiguring IP addresses
1547           when using VTI.
1548
1549       priority
1550           The priority in the kernel SPD/SAD database, when matching up
1551           packets. Each kernel (XFRM, OSX, etc) has its own mechanism for
1552           setting the priority. Setting this option to non-zero passes the
1553           priority to the kernel stack unmodified. The maximum value depends
1554           on the stack. It is recommended not to exceed 65536
1555
1556           XFRM use a priority system based on "most specific match first". It
1557           uses an internal algorithm to calculate these based on network
1558           prefix length, protocol and port selectors. A lower value means a
1559           higher priority.
1560
1561           Typical values are about the 2000 range. These can be seen on the
1562           XFRM stack using ip xfrm policy when the connection is up. For
1563           "anonymous IPsec" or Opportunistic Encryption based connections, a
1564           much lower priority (65535) is used to ensure administrator
1565           configured IPsec always takes precedence over opportunistic IPsec.
1566
1567       sendca
1568           How much of our available X.509 trust chain to send with the End
1569           certificate, excluding any root CA's. Specifying issuer sends just
1570           the issuing intermediate CA, while
1571            all will send the entire chain of intermediate CA's.none (the
1572           default) will not send any CA certs.
1573
1574       labeled-ipsec
1575           This option is obsolete. To enable labeled IPsec, setting the
1576           policy-label= is enough. See also policy-label= and
1577           secctx-attr-type=
1578
1579       policy-label
1580           The string representation of an access control security label that
1581           is interpreted by the LSM (e.g. SELinux) for use with Labeled
1582           IPsec. See also labeled-ipsec= and secctx-attr-type=. For example,
1583           policy-label=system_u:object_r:ipsec_spd_t:s0-s15:c0.c1023
1584
1585       failureshunt
1586           what to do with packets when negotiation fails. The default is
1587           none: no shunt; passthrough, drop, and reject have the obvious
1588           meanings.
1589
1590       negotiationshunt
1591           What to do with packets during the IKE negotiation. Valid options
1592           are hold (the default) or passthrough. This should almost always be
1593           left to the default hold value to avoid cleartext packet leaking.
1594           The only reason to set this to passthrough is if plaintext service
1595           availability is more important than service security or privacy, a
1596           scenario that also implies failureshunt=passthrough and most likely
1597           authby=%null using Opportunistic Encryption.
1598

CONFIG SECTIONS

1600       At present, the only config section known to the IPsec software is the
1601       one named setup, which contains information used when the software is
1602       being started (see ipsec_setup(8)). Here's an example:
1603
1604
1605           config setup
1606                logfile=/var/log/pluto.log
1607                plutodebug=all
1608
1609       Parameters are optional unless marked “(required)”.
1610
1611       The currently-accepted parameter names in a config setup section are:
1612
1613       protostack
1614           decide which protocol stack is going to be used. Valid values are
1615           "xfrm" and "bsd". This option should no longer be set, as the stack
1616           is currently auto-detected. The values "klips, "mast", "netkey",
1617           "native", "kame" and "auto" are obsolete. The option is kept only
1618           because it is suspected that Linux and BSD will get userspace
1619           stacks with IPsec support soon (such as dpdk).
1620
1621       listen
1622           IP address to listen on (default depends on interfaces= setting).
1623           Currently only accepts one IP address.
1624
1625       ike-socket-bufsize
1626           Set the IKE socket buffer size. Default size is determined by the
1627           OS (as of writing, this seems to be set to 212992. On Linux this is
1628           visible via /proc/sys/net/core/rmem_default and
1629           /proc/sys/net/core/wmem_default. On Linux, this option uses
1630           SO_RCVBUFFORCE and SO_SNDBUFFORCE so that it can override
1631           rmem_max/wmem_max values of the OS. This requires CAP_NET_ADMIN
1632           (which is also required for other tasks). This option can also be
1633           toggled on a running system using ipsec whack --ike-socket-bufsize
1634           bufsize.
1635
1636       ike-socket-errqueue
1637           Whether to enable or disable receiving socket errors via
1638           IP_RECVERR. The default is enabled. This will cause the socket to
1639           receive, process and log socket errors, such as ICMP unreachable
1640           messages or Connection Refused messages. Disabling this only makes
1641           sense on very busy servers, and even then it might not make much of
1642           a difference. This option can also be toggled on a running system
1643           using ipsec whack --ike-socket-errqueue-toggle.
1644
1645       listen-udp
1646           Whether the pluto IKE daemon should listen on the standard UDP
1647           ports of 500 and 4500. The value "yes" means to listen on these
1648           ports, and is the default. This should almost never be disabled. In
1649           the rare case where it is known that only ever TCP or non-standard
1650           UDP ports will be used, this option can disable the standard UDP
1651           ports. Connections can specify their own non-standard port using
1652           leftikeport=.
1653
1654       listen-tcp
1655           Whether the pluto IKE daemon should listen on the (pseudo) standard
1656           TCP port 4500. The value "no" is the current default, but this will
1657           be changed in the future to "yes". The TCP usage complies to RFC
1658           8229 for IKE and ESP over TCP support. Connections can specify
1659           their own non-standard port using leftikeport=.
1660
1661       nflog-all
1662           If set, the NFLOG group number to log all pre-crypt and
1663           post-decrypt traffic to. The default value of 0 means no logging at
1664           all. This option is only available on linux kernel 2.6.14 and
1665           later. It allows common network utilities such as tcpdump,
1666           wireshark and dumpcap, to use nflog:XXX pseudo interfaces where XXX
1667           is the nflog group number. During startup and shutdown of the IPsec
1668           service, iptables commands will be used to add or remove the global
1669           NFLOG table rules. The rules are setup with the nflog-prefix
1670           all-ipsec. See also the per-connection nflog option.
1671
1672       keep-alive
1673           The delay (in seconds) for NAT-T keep-alive packets, if these are
1674           enabled using nat-keepalive This parameter may eventually become
1675           per-connection.
1676
1677       virtual-private
1678           contains the networks that are allowed as (left|right)subnet= for
1679           the remote clients when using the vhost: or vnet: keywords in the
1680           (left|right)subnet= parameters. In other words, the address ranges
1681           that may live behind a NAT router through which a client connects.
1682           This value is usually set to all the RFC-1918 address space,
1683           excluding the space used in the local subnet behind the NAT (An IP
1684           address cannot live at two places at once). IPv4 address ranges are
1685           denoted as %v4:a.b.c.d/mm and IPv6 is denoted as
1686           %v6:aaaa::bbbb:cccc:dddd:eeee/mm. One can exclude subnets by using
1687           the !. For example, if the VPN server is giving access to
1688           192.168.1.0/24, this option should be set to:
1689           virtual-private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:!192.168.1.0/24.
1690           This parameter is only needed on the server side and not on the
1691           client side that resides behind the NAT router, as the client will
1692           just use its IP address for the inner IP setting. This parameter
1693           may eventually become per-connection. See also leftsubnet=
1694
1695           Note: It seems that T-Mobile in the US and Rogers/Fido in Canada
1696           have started using 25.0.0.0/8 as their pre-NAT range. This range
1697           technically belongs to the Defence Interoperable Network Services
1698           Authority (DINSA), an agency of the Ministry of Defence of the
1699           United Kingdom. The network range seems to not have been announced
1700           for decades, which is probably why these organisations "borrowed"
1701           this range. To support roadwarriors on these 3G networks, you might
1702           have to add it to the virtual-private= line.
1703
1704       myvendorid
1705           The string to use as our vendor id (VID) when send-vendorid=yes.
1706           The default is OE-Libreswan-VERSION.
1707
1708       nhelpers
1709           how many pluto helpers are started to help with cryptographic
1710           operations. Pluto will start as many helpers as the number of
1711           CPU's, minus 1 to dedicate to the main thread. For machines with
1712           less than 4 CPU's, an equal number of helpers to CPU's are started.
1713           A value of 0 forces pluto to do all operations inline using the
1714           main process. A value of -1 tells pluto to perform the above
1715           calculation. Any other value forces the number to that amount.
1716
1717       seedbits
1718           Pluto uses the NSS crypto library as its random source. Some
1719           government Three Letter Agencies require that pluto reads
1720           additional bits from /dev/random and feed these into the NSS RNG
1721           before drawing random from the NSS library, despite the NSS library
1722           itself already seeding its internal state. This process can block
1723           pluto for an extended time during startup, depending on the entropy
1724           of the system. Therefore, the default is to not perform this
1725           redundant seeding. If specifying a value, it is recommended to
1726           specify at least 460 bits (for FIPS) or 440 bits (for BSI).
1727
1728       ikev1-secctx-attr-type
1729           The value for the IKEv1 IPsec SA security context attribute
1730           identifier that is used for Labeled IPsec. Defaults to the private
1731           use IANA value 32001 from the IPsec SA attributes registry. Old
1732           openswan versions might still be using the (stolen) value 10, which
1733           has since been assigned by IANA for something else. Other values
1734           are not recommended unless IANA assigns an actual value for this
1735           option. Labeled IPsec using IKEv2 does not use this option, it only
1736           uses an IANA allocated Notify number. See also policy-label.
1737
1738       ikev1-policy
1739           What to do with received IKEv1 packets. Valid options are accept
1740           (default), reject which will reply with an error, and drop which
1741           will silently drop any received IKEv1 packet. If this option is set
1742           to drop or reject, an attempt to load an IKEv1 connection will
1743           fail, as these connections would never be able to receive a packet
1744           for processing.
1745
1746       crlcheckinterval
1747           interval expressed in second units, for example crlcheckinterval=8h
1748           for 8 hours, after which pluto will fetch new Certificate
1749           Revocation List (CRL) from crl distribution points. List of used
1750           CRL distribution points are collected from CA certificates and end
1751           certificates. Loaded X.509 CRL's are verified to be valid and
1752           updates are imported to NSS database. If set to 0, which is also
1753           the default value if this option is not specified, CRL updating is
1754           disabled.
1755
1756       crl-strict
1757           if not set, pluto is tolerant about missing or expired X.509
1758           Certificate Revocation Lists (CRL's), and will allow peer
1759           certificates as long as they do not appear on an expired CRL. When
1760           this option is enabled, all connections with an expired or missing
1761           CRL will be denied. Active connections will be terminated at rekey
1762           time. This setup is more secure, but vulnerable to downtime if the
1763           CRL expires. Acceptable values are yes or no (the default). This
1764           option used to be called strictcrlpolicy.
1765
1766       curl-iface
1767           The name of the interface that is used for CURL lookups. This is
1768           needed on rare situations where the interface needs to be forced to
1769           be different from the default interface used based on the routing
1770           table.
1771
1772       curl-timeout
1773           The timeout for the curl library calls used to fetch CRL and OCSP
1774           requests. The default is 5s.
1775
1776       ocsp-enable
1777           Whether to perform Online Certificate Store Protocol ("OCSP")
1778           checks on those certificates that have an OCSP URI defined.
1779           Acceptable values are yes or no (the default).
1780
1781       ocsp-strict
1782           if set to no, pluto is tolerant about failing to obtain an OCSP
1783           responses and a certificate is not rejected when the OCSP request
1784           fails, only when the OCSP request succeeds and lists the
1785           certificate as revoked. If set to yes, any failure on obtaining an
1786           OCSP status for a certificate will be fatal and the certificate
1787           will be rejected. Acceptable values are yes or no (the default).
1788
1789           The strict mode refers to the NSS
1790           ocspMode_FailureIsVerificationFailure mode, while non-strict mode
1791           refers to the NSS ocspMode_FailureIsNotAVerificationFailure mode.
1792
1793       ocsp-method
1794           The HTTP methods used for fetching OCSP data. Valid options are get
1795           (the default) and post. Note that this behaviour depends on the NSS
1796           crypto library that is actually performing the fetching. When set
1797           to the get method, post is attempted only as fallback in case of
1798           failure. When set to post, only the post method is ever used.
1799
1800       ocsp-timeout
1801           The time until an OCSP request is aborted and considered failed.
1802           The default value is 2 seconds.
1803
1804       ocsp-uri
1805           The URI to use for OCSP requests instead of the default OCSP URI
1806           listed in the CA certificate. This requires the ocsp-trustname
1807           option to be set to the nick (friendly name) of the OCSP server
1808           certificate, which needs to be present in the NSS database. These
1809           option combined with the next option sets the OCSP default
1810           responder.
1811
1812       ocsp-trustname
1813           The nickname of the certificate that has been imported into the NSS
1814           database of the server handling the OCSP requests. This requires
1815           the ocsp-uri option to be set as well. This option and the previous
1816           options sets the OCSP default responder.
1817
1818       ocsp-cache-size
1819           The maximum size (in number of certificates) of OCSP responses that
1820           will be kept in the cache. The default is 1000. Setting this value
1821           to 0 means the cache is disabled.
1822
1823       ocsp-cache-min-age
1824           The minimum age (in seconds) before a new fetch will be attempted.
1825           The default is 1 hour.
1826
1827       ocsp-cache-max-age
1828           The maximum age (in seconds) before a new fetch will be attempted.
1829           The default is 1 day.
1830
1831       syslog
1832           the syslog(2) “facility” name and priority to use for
1833           startup/shutdown log messages, default daemon.error.
1834
1835       plutodebug
1836           how much Pluto debugging output should be logged. An empty value,
1837           or the magic value none, means no debug output (the default).
1838           Otherwise only the specified types of output (a quoted list, names
1839           without the --debug- prefix, separated by white space) are enabled;
1840
1841           The current option values are base that represents moderate amounts
1842           of information, cpu-usage for getting timing/load based information
1843           (best used without any other debugging options), crypt for all
1844           crypto related operations and tmi (Too Much Information) for
1845           excessive logging. To log any sensitive private key or password
1846           material, use the special private value.
1847
1848           The old plutodebug options (control, controlmore, x509, kernel,
1849           etc) are mapped to either base or tmi. Note that all maps to base
1850           and not tmi.
1851
1852       uniqueids
1853           Whether IDs should be considered identifying remote parties
1854           uniquely. Acceptable values are yes (the default) and no.
1855           Participant IDs normally are unique, so a new connection instance
1856           using the same remote ID is almost invariably intended to replace
1857           an old existing connection.
1858
1859           When the connection is defined to be a server (using xauthserver=)
1860           and the connection policy is authby=secret, this option is ignored
1861           (as of 3.20) and old connections will never be replaced. This
1862           situation is commonly known as clients using a "Group ID".
1863
1864           This option may disappear in the near future. People using
1865           identical X.509 certificates on multiple devices are urged to
1866           upgrade to use separate certificates per client and device.
1867
1868       logfile
1869           do not use syslog, but rather log to stderr, and direct stderr to
1870           the argument file. This option used to be called plutostderrlog=
1871
1872       logappend
1873           If pluto is instructed to log to a file using logfile=, this option
1874           determines whether the log file should be appended to or
1875           overwritten. Valid options are yes (the default) to append and no
1876           to overwrite. Since on modern systems, pluto is restarted by other
1877           daemons, such as systemd, this option should be left at its default
1878           yes value to preserve the log entries of previous runs of pluto.
1879           The option is mainly of use for running the test suite, which needs
1880           to create new log files from scratch.
1881
1882       logip
1883           If pluto is instructed to log the IP address of incoming
1884           connections. Valid options are yes (the default) and no. Note that
1885           this only affects regular logging. Any enabled debugging via
1886           plutodebug= will still contain IP addresses of peers. This option
1887           is mostly meant for servers that want to avoid logging IP addresses
1888           of incoming clients. Other identifiable information might still be
1889           logged, such as ID payloads and X.509 certificate details. When
1890           using ID of type IP address, this option will not hide the actual
1891           IP address as part of the ID. Most deployments will not want to
1892           change this from the default. If logging of IP addresses is
1893           unwanted, audit-log=no should also be set.
1894
1895       audit-log
1896           Whether pluto should produce Linux Auditing System log messages. If
1897           enabled, pluto will log start, stop and fail for the negotiation of
1898           IKE and IPsec SA's. The kernel will also log success and failures
1899           for actually adding and removing IPsec SA's from the kernel's SADB.
1900           Valid options are yes(the default) and no. On non-Linux systems,
1901           this option is ignored. If enabled but the kernel is lacking audit
1902           support, audit messages are not sent. If the kernel has audit
1903           support and using it fails, pluto will abort. Note that for
1904           compliance reasons, audit log messages contain the relevant IP
1905           addresses, even if logip=no.
1906
1907       logtime
1908           When pluto is directed to log to a file using logfile=, this option
1909           determines whether or not to log the current timestamp as prefix.
1910           Values are yes (the default) or no. The no value can be used to
1911           create logs without ephemeral timestamps, such as those created
1912           when running the test suite. This option used to be called
1913           plutostderrlogtime=
1914
1915       ddos-mode
1916           The startup mode of the DDoS defense mechanism. Acceptable values
1917           are busy, unlimited or auto (the default). This option can also be
1918           given to the IKE daemon while running, for example by issuing ipsec
1919           whack --ddos--busy. When in busy mode, pluto activates anti-DDoS
1920           counter measures. Currently, counter measures consist of requiring
1921           IKEv2 anti-DDoS cookies on new incoming IKE requests, and a more
1922           aggressive cleanup of partially established or AUTH_NULL
1923           connections.
1924
1925       ddos-ike-threshold
1926           The number of half-open IKE SAs before the pluto IKE daemon will be
1927           placed in busy mode. When in busy mode, pluto activates anti-DDoS
1928           counter measures. The default is 25000. See also ddos-mode and
1929           ipsec whack --ddos-XXX.
1930
1931       global-redirect
1932           Whether to send requests for the remote peer to redirect IKE/IPsec
1933           SA's during IKE_SA_INIT. Valid options are no (the default), yes
1934           and auto, where auto means that the requests will be sent if DDoS
1935           mode is active (see ddos-mode). If set, the option
1936           global-redirect-to= must also be set to indicate where to redirect
1937           peers to. For specific connection redirection after IKE SA
1938           authentication, see the send-redirect= and redirect-to= options.
1939           This configuration can be changed at runtime via the ipsec whack
1940           --global-redirect command.
1941
1942       global-redirect-to
1943           Where to send remote peers to via the global-redirect option. This
1944           can be a list, or a single entry, of IP addresses or hostnames
1945           (FQDNs). If there is a list of entries, they must be separated with
1946           comma's. One specified entry means all peers will be redirected to
1947           it, while multiple specified entries means peers will be evenly
1948           distributed across the specified servers. This configuration can be
1949           changed at runtime via the ipsec whack --global-redirect-to
1950           command.
1951
1952       max-halfopen-ike
1953           The number of half-open IKE SAs before the IKE daemon starts
1954           refusing all new IKE attempts. Established IKE peers are not
1955           affected. The default value is 50000.
1956
1957       shuntlifetime
1958           The time until bare shunts (kernel policies not associated with
1959           connections) are deleted from the kernel. The default value is 15m.
1960           When using Opportunistic Encryption to a specific host fails, the
1961           system will either install a %pass or %hold shunt to let the
1962           traffic out clear text or block it. During the the shuntlifetime,
1963           no new Opportunistic Encryption attempt will be started, although
1964           the system will still respond to incoming OE requests from the
1965           remote IP. See also failureshunt and negotiationshunt
1966
1967       xfrmlifetime
1968           The time in seconds until the XFRM acquire state times out. The
1969           default value is 30 seconds. For auto=ondemand connections and
1970           Opportunistic connections an IPsec policy is installed in the
1971           kernel. If an incoming or outgoing packet matches this policy, a
1972           state is created in the kernel and the kernel sends an ACQUIRE
1973           message to the IKE daemon pluto. While this state is in place, no
1974           new acquires will come in for this connection. The default should
1975           be fine for most people. One use case of shortening these is if
1976           opportunistc encryption is used towards cloud instances that can
1977           quickly re-use IP addresses. This value is only used during the
1978           libreswan startup process by the ipsec _stackmanager helper. See
1979           also failureshunt and negotiationshunt
1980
1981       dumpdir
1982           in what directory should things started by setup (notably the Pluto
1983           daemon) be allowed to dump core? The default value is
1984           /var/run/pluto. When SELinux runs in enforced mode, changing this
1985           requires a similar change in the SELinux policy for the pluto
1986           daemon.
1987
1988       statsbin
1989           This option specifies an optional external program to report tunnel
1990           state changes too. The default is not to report tunnel state
1991           changes. This program can be used to notify the user's desktop
1992           (dbus, NetworkManager) or to report tunnel changes to a central
1993           logging server.
1994
1995       ipsecdir
1996           Specifies a directory for administrator-controlled configuration
1997           files and directories. The default value is /etc/ipsec.d. It may
1998           contain the following files and directories:
1999
2000           passwd
2001               (optional) for XAUTH support if not using PAM (this file should
2002               not be world-readable). See README.XAUTH for more information.
2003
2004           nsspassword
2005               (optional) passwords needed to unlock the NSS database in
2006               /var/lib/ipsec/nss (this file should not be world-readable).
2007               See README.nss for more information.
2008
2009           policies/
2010               a directory containing policy group configuration information.
2011               See POLICY GROUP FILES in this document for more information.
2012
2013           cacerts/
2014               DEPRECATED: a directory to store trust anchors (root
2015               certificate authority certificates). The preferred (and
2016               default) approach is to store CA certs in the NSS database
2017               instead. See README.nss for more information.
2018
2019           crls/
2020               DEPRECATED: a directory to store certificate revocation lists.
2021               The preferred (and default) approach is to store CRLs in the
2022               NSS database instead. See README.nss for more information.
2023
2024           When SELinux runs in enforced mode, changing this requires a
2025           similar change in the SELinux policy for the pluto daemon.
2026
2027       nssdir
2028           Specifies a directory for NSS database files. The default value is
2029           /var/lib/ipsec/nss. It may contain the following files:
2030
2031           pkcs11.txt
2032               Detailed info about NSS database creation parameteres.
2033
2034           cert9.db
2035               NSS Certificate database.
2036
2037           key4.db
2038               NSS Key database.
2039
2040           When SELinux runs in enforced mode, changing this requires a
2041           similar change in the SELinux policy for the pluto daemon.
2042
2043       secretsfile
2044           pathname of the file that stores the secret credentials such as
2045           preshared keys (PSKs). See man ipsec.secrets for the syntax. The
2046           default value is /etc/ipsec.secrets.
2047
2048       seccomp
2049           Set the seccomp kernel syscall whitelisting feature. When set to
2050           enabled, if pluto calls a syscall that is not on the compiled-in
2051           whitelist, the kernel will assume an exploit is attempting to use
2052           pluto for malicious access to the system and terminate the pluto
2053           daemon. When set to tolerant, the kernel will only block the rogue
2054           syscall and pluto will attempt to continue. If set to disabled,
2055           pluto is allowed to call any syscall offered by the kernel,
2056           although it might be restricted via other security mechanisms, such
2057           as capabilities, SElinux, AppArmor or other OS security features.
2058
2059           The current default is disabled, but it is expected that in the
2060           future this feature will be enabled on all supported operating
2061           systems. Similarly, it is expected that further privilege
2062           separation will reduce the allowed syscalls - for example for the
2063           crypto helpers or DNS helpers.
2064
2065           Warning: The restrictions of pluto are inherited by the updown
2066           scripts, so these scripts are also not allowed to use syscalls that
2067           are forbidden for pluto.
2068
2069           This feature can be tested using ipsec whack --seccomp-crashtest.
2070           Warning: With seccomp=enabled, pluto will be terminated by the
2071           kernel. With seccomp=tolerant or seccomp=disabled, pluto will
2072           report the results of the seccomp test. SECCOMP will log the
2073           forbidden syscall numbers to the audit log, but only with
2074           seccomp=enabled. The tool scmp_sys_resolver from the libseccomp
2075           development package can be used to translate the syscall number
2076           into a name. See programs/pluto/pluto_seccomp.c for the list of
2077           allowed syscalls.
2078
2079       dnssec-enable
2080           Whether pluto should perform dnssec validation using libunbound,
2081           provided libreswan was compiled with USE_DNSSEC. A value of yes
2082           (the default) means pluto should perform DNSSEC validation. Note
2083           that pluto reads the file /etc/resolv.conf to determine which
2084           nameservers to use.
2085
2086       dnssec-rootkey-file
2087           The location of the DNSSEC root zone public key file. The default
2088           is /var/lib/unbound/root.key but this can be changed at compile
2089           time.
2090
2091       dnssec-anchors
2092           The location of a file containing additional DNSSEC Trust Anchors.
2093           This can be used when a network is using split-DNS and the internal
2094           hierarchy is using DNSSEC trust anchors. There is no default value.
2095

OPPORTUNISTIC CONNS

2097       For Opportunistic connections, the system requires creating special
2098       named conns that are used to implement the default policy groups.
2099       Currently, these names cannot be changed.
2100
2101
2102           conn clear
2103                type=passthrough
2104                authby=never
2105                left=%defaultroute
2106                right=%group
2107                auto=route
2108
2109           conn clear-or-private
2110                type=passthrough
2111                left=%defaultroute
2112                leftid=%myid
2113                right=%opportunisticgroup
2114                failureshunt=passthrough
2115                keyingtries=3
2116                ikelifetime=1h
2117                salifetime=1h
2118                rekey=no
2119                auto=route
2120
2121           conn private-or-clear
2122                type=tunnel
2123                left=%defaultroute
2124                leftid=%myid
2125                right=%opportunisticgroup
2126                failureshunt=passthrough
2127                keyingtries=3
2128                ikelifetime=1h
2129                salifetime=1h
2130                rekey=no
2131                auto=route
2132
2133           conn private
2134                type=tunnel
2135                left=%defaultroute
2136                leftid=%myid
2137                right=%opportunisticgroup
2138                failureshunt=drop
2139                keyingtries=3
2140                ikelifetime=1h
2141                salifetime=1h
2142                rekey=no
2143                auto=route
2144
2145           conn block
2146                type=reject
2147                authby=never
2148                left=%defaultroute
2149                right=%group
2150                auto=route
2151
2152
2153       These conns will only work if %defaultroute works. The leftid will be
2154       the interfaces IP address by default, but it can also be set to
2155       %fromcert or use a DNS name.
2156

POLICY GROUP FILES

2158       The optional files under /etc/ipsec.d/policies, including
2159
2160
2161           /etc/ipsec.d/policies/clear
2162           /etc/ipsec.d/policies/clear-or-private
2163           /etc/ipsec.d/policies/private-or-clear
2164           /etc/ipsec.d/policies/private
2165           /etc/ipsec.d/policies/block
2166
2167
2168       may contain policy group configuration information to supplement
2169       ipsec.conf. Their contents are not security-sensitive.
2170
2171       These files are text files. Each consists of a list of CIDR blocks, one
2172       per line. White space followed by # followed by anything to the end of
2173       the line is a comment and is ignored, as are empty lines.
2174
2175       A connection in ipsec.conf that has right=%group or
2176       right=%opportunisticgroup is a policy group connection. When a policy
2177       group file of the same name is loaded at system start, the connection
2178       is instantiated such that each CIDR block serves as an instance's right
2179       value. The system treats the resulting instances as normal connections.
2180
2181       For example, given a suitable connection definition private, and the
2182       file /etc/ipsec.d/policies/private with an entry 192.0.2.3, the system
2183       creates a connection instance private#192.0.2.3.  This connection
2184       inherits all details from private, except that its right client is
2185       192.0.2.3.
2186

DEFAULT POLICY GROUPS

2188       The standard Libreswan install includes several policy groups which
2189       provide a way of classifying possible peers into IPsec security
2190       classes: private (talk encrypted only), private-or-clear (prefer
2191       encryption), clear-or-private (respond to requests for encryption),
2192       clear and block.
2193

CHOOSING A CONNECTION [THIS SECTION IS EXTREMELY OUT OF DATE

2195       When choosing a connection to apply to an outbound packet caught with a
2196       %trap, the system prefers the one with the most specific eroute that
2197       includes the packet's source and destination IP addresses. Source
2198       subnets are examined before destination subnets. For initiating, only
2199       routed connections are considered. For responding, unrouted but added
2200       connections are considered.
2201
2202       When choosing a connection to use to respond to a negotiation that
2203       doesn't match an ordinary conn, an opportunistic connection may be
2204       instantiated. Eventually, its instance will be /32 -> /32, but for
2205       earlier stages of the negotiation, there will not be enough information
2206       about the client subnets to complete the instantiation.
2207

FILES

2209           /etc/ipsec.conf
2210           /etc/ipsec.d/policies/clear
2211           /etc/ipsec.d/policies/clear-or-private
2212           /etc/ipsec.d/policies/private-or-clear
2213           /etc/ipsec.d/policies/private
2214           /etc/ipsec.d/policies/block
2215

SEE ALSO

2217       ipsec(8), ipsec_auto(8), ipsec_rsasigkey(8)
2218

HISTORY

2220       Designed for the FreeS/WAN project <https://www.freeswan.org> by Henry
2221       Spencer.
2222

BUGS

2224       Before reporting new bugs, please ensure you are using the latest
2225       version of Libreswan.
2226
2227       When type or failureshunt is set to drop or reject, Libreswan blocks
2228       outbound packets using eroutes, but assumes inbound blocking is handled
2229       by the firewall. Libreswan offers firewall hooks via an “updown”
2230       script. However, the default ipsec _updown provides no help in
2231       controlling a modern firewall.
2232
2233       Including attributes of the keying channel (authentication methods,
2234       ikelifetime, etc.) as an attribute of a connection, rather than of a
2235       participant pair, is dubious and incurs limitations.
2236
2237       The use of %any with the protoport= option is ambiguous. Should the SA
2238       permits any port through or should the SA negotiate any single port
2239       through? The first is a basic conn with a wildcard. The second is a
2240       template. The second is the current behaviour, and it's wrong for quite
2241       a number of uses involving TCP. The keyword %one may be introduced in
2242       the future to separate these two cases.
2243
2244       It would be good to have a line-continuation syntax, especially for the
2245       very long lines involved in RSA signature keys.
2246
2247       The ability to specify different identities, authby, and public keys
2248       for different automatic-keyed connections between the same participants
2249       is misleading; this doesn't work dependably because the identity of the
2250       participants is not known early enough. This is especially awkward for
2251       the “Road Warrior” case, where the remote IP address is specified as
2252       0.0.0.0, and that is considered to be the “participant” for such
2253       connections.
2254
2255       If conns are to be added before DNS is available, left=FQDN,
2256       leftnextop=FQDN, and leftrsasigkey=%dnsonload will fail.
2257       ipsec_pluto(8) does not actually use the public key for our side of a
2258       conn but it isn't generally known at a add-time which side is ours
2259       (Road Warrior and Opportunistic conns are currently exceptions).
2260
2261       The myid option does not affect explicit
2262        ipsec auto --add or ipsec auto --replace commands for implicit conns.
2263

AUTHOR

2265       Paul Wouters
2266           documenter
2267
2268
2269
2270libreswan                         05/24/2022                     IPSEC.CONF(5)
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