1rpc.gssd(8) System Manager's Manual rpc.gssd(8)
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6 rpc.gssd - rpcsec_gss daemon
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9 rpc.gssd [-f] [-n] [-k keytab] [-l] [-p pipefsdir] [-v] [-r] [-d
10 ccachedir]
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13 The rpcsec_gss protocol gives a means of using the gss-api generic
14 security api to provide security for protocols using rpc (in particu‐
15 lar, nfs). Before exchanging any rpc requests using rpcsec_gss, the
16 rpc client must first establish a security context. The linux kernel's
17 implementation of rpcsec_gss depends on the userspace daemon rpc.gssd
18 to establish security contexts. The rpc.gssd daemon uses files in the
19 rpc_pipefs filesystem to communicate with the kernel.
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23 -f Runs rpc.gssd in the foreground and sends output to stderr (as
24 opposed to syslogd)
25 -n By default, rpc.gssd treats accesses by the user with UID 0 spe‐
27 cially, and uses "machine credentials" for all accesses by that
28 user which require Kerberos authentication. With the -n option,
29 "machine credentials" will not be used for accesses by UID 0.
30 Instead, credentials must be obtained manually like all other
31 users. Use of this option means that "root" must manually
32 obtain Kerberos credentials before attempting to mount an nfs
33 filesystem requiring Kerberos authentication.
34 -k keytab
36 Tells rpc.gssd to use the keys found in keytab to obtain
37 "machine credentials". The default value is "/etc/krb5.keytab".
38 Previous versions of rpc.gssd used only "nfs/*" keys found
40 within the keytab. To be more consistent with other implementa‐
41 tions, we now look for specific keytab entries. The search
42 order for keytabs to be used for "machine credentials" is now:
43 <HOSTNAME>$@<REALM>
44 root/<hostname>@<REALM>
45 nfs/<hostname>@<REALM>
46 host/<hostname>@<REALM>
47 root/<anyname>@<REALM>
48 nfs/<anyname>@<REALM>
49 host/<anyname>@<REALM>
50 If this search order does not use the correct key then provide a
52 keytab file that contains only correct keys.
53 -l Tells rpc.gssd to limit session keys to Single DES even if the
55 kernel supports stronger encryption types. Service ticket
56 encryption is still governed by what the KDC believes the target
57 server supports. This way the client can access a server that
58 has strong keys in its keytab for ticket decryption but whose
59 kernel only supports Single DES.
60 The alternative is to put only Single DES keys in the server's
62 keytab and limit encryption types for its principal to Single
63 DES on the KDC which will cause service tickets for this server
64 to be encrypted using only Single DES and (as a side-effect)
65 contain only Single DES session keys.
66 This legacy behaviour is only required for older servers (pre
68 nfs-utils-1.2.4). If the server has a recent kernel, Kerberos
69 implementation and nfs-utils it will work just fine with
70 stronger encryption.
71 Note: This option is only available with Kerberos libraries that
73 support setable encryption types.
74 -p path
76 Tells rpc.gssd where to look for the rpc_pipefs filesystem. The
77 default value is "/var/lib/nfs/rpc_pipefs".
78 -d directory
80 Tells rpc.gssd where to look for Kerberos credential files. The
81 default value is "/tmp". This can also be a colon separated
82 list of directories to be searched for Kerberos credential
83 files. Note that if machine credentials are being stored in
84 files, then the first directory on this list is where the
85 machine credentials are stored.
86 -v Increases the verbosity of the output (can be specified multiple
88 times).
89 -r If the rpcsec_gss library supports setting debug level,
91 increases the verbosity of the output (can be specified multiple
92 times).
93 -R realm
95 Kerberos tickets from this realm will be preferred when scanning
96 available credentials cache files to be used to create a con‐
97 text. By default, the default realm, as configured in the Ker‐
98 beros configuration file, is preferred.
99 -t timeout
101 Timeout, in seconds, for kernel gss contexts. This option allows
102 you to force new kernel contexts to be negotiated after timeout
103 seconds, which allows changing Kerberos tickets and identities
104 frequently. The default is no explicit timeout, which means the
105 kernel context will live the lifetime of the Kerberos service
106 ticket used in its creation.
107 -T timeout
109 Timeout, in seconds, to create an RPC connection with a server
110 while establishing an authenticated gss context for a user. The
111 default timeout is set to 5 seconds. If you get messages like
112 "WARNING: can't create tcp rpc_clnt to server %servername% for
113 user with uid %uid%: RPC: Remote system error - Connection timed
114 out", you should consider an increase of this timeout.
115
117 rpc.svcgssd(8)
118
120 Dug Song <dugsong@umich.edu>
121 Andy Adamson <andros@umich.edu>
122 Marius Aamodt Eriksen <marius@umich.edu>
123 J. Bruce Fields <bfields@umich.edu>
124 14 Mar 2007 rpc.gssd(8)