1ROUTE(8)              Linux System Administrator's Manual             ROUTE(8)
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NAME

6       route - show / manipulate the IP routing table
7

SYNOPSIS

9       route [-CFvnNee] [-A family |-4|-6]
10
11       route  [-v] [-A family |-4|-6] add [-net|-host] target [netmask Nm] [gw
12              Gw] [metric N] [mss M] [window W] [irtt I] [reject] [mod]  [dyn]
13              [reinstate] [[dev] If]
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15       route  [-v] [-A family |-4|-6] del [-net|-host] target [gw Gw] [netmask
16              Nm] [metric M] [[dev] If]
17
18       route  [-V] [--version] [-h] [--help]
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20

NOTE

22       This program is obsolete. For replacement check ip route.
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24

DESCRIPTION

26       Route manipulates the kernel's IP routing tables.  Its primary  use  is
27       to  set up static routes to specific hosts or networks via an interface
28       after it has been configured with the ifconfig(8) program.
29
30       When the add or del  options  are  used,  route  modifies  the  routing
31       tables.   Without these options, route displays the current contents of
32       the routing tables.
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34

OPTIONS

36       -A family
37              use the specified address family (eg `inet'). Use  route  --help
38              for  a  full list. You can use -6 as an alias for --inet6 and -4
39              as an alias for -A inet
40
41
42       -F     operate on the kernel's FIB (Forwarding Information Base)  rout‐
43              ing table.  This is the default.
44
45       -C     operate on the kernel's routing cache.
46
47       -v     select verbose operation.
48
49       -n     show numerical addresses instead of trying to determine symbolic
50              host names. This is useful if you are trying  to  determine  why
51              the route to your nameserver has vanished.
52
53       -e     use  netstat(8)-format  for  displaying  the routing table.  -ee
54              will generate a very long line  with  all  parameters  from  the
55              routing table.
56
57       del    delete a route.
58
59       add    add a new route.
60
61       target the destination network or host. You can provide an addresses or
62              symbolic network or host name. Optionally you can use /prefixlen
63              notation instead of using the netmask option.
64
65       -net   the target is a network.
66
67       -host  the target is a host.
68
69       netmask NM
70              when adding a network route, the netmask to be used.
71
72       gw GW  route packets via a gateway.
73              NOTE:  The  specified gateway must be reachable first. This usu‐
74              ally means that you have to set up a static route to the gateway
75              beforehand.  If  you  specify  the  address of one of your local
76              interfaces, it will be used to decide  about  the  interface  to
77              which the packets should be routed to. This is a BSDism compati‐
78              bility hack.
79
80       metric M
81              set the metric field in the routing table (used by routing  dae‐
82              mons) to M. If this option is not specified the metric for inet6
83              (IPv6) address family  defaults  to  '1',  for  inet  (IPv4)  it
84              defaults  to  '0'.  You should always specify an explicit metric
85              value to not rely on those defaults  -  they  also  differ  from
86              iproute2.
87
88       mss M  sets  MTU  (Maximum  Transmission Unit) of the route to M bytes.
89              Note that the current implementation of the route  command  does
90              not allow the option to set the Maximum Segment Size (MSS).
91
92       window W
93              set  the  TCP  window  size for connections over this route to W
94              bytes. This is typically only used on AX.25  networks  and  with
95              drivers unable to handle back to back frames.
96
97       irtt I set  the initial round trip time (irtt) for TCP connections over
98              this route to I milliseconds (1-12000). This is  typically  only
99              used on AX.25 networks. If omitted the RFC 1122 default of 300ms
100              is used.
101
102       reject install a blocking route, which will force  a  route  lookup  to
103              fail.   This  is  for  example  used to mask out networks before
104              using the default route. This is NOT for firewalling.
105
106       mod, dyn, reinstate
107              install a dynamic or modified route. These flags are  for  diag‐
108              nostic purposes, and are generally only set by routing daemons.
109
110       dev If force  the  route to be associated with the specified device, as
111              the kernel will otherwise try to determine the device on its own
112              (by  checking already existing routes and device specifications,
113              and where the route is added to). In most  normal  networks  you
114              won't need this.
115
116              If  dev  If is the last option on the command line, the word dev
117              may be omitted, as it's the default. Otherwise the order of  the
118              route modifiers (metric netmask gw dev) doesn't matter.
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120

EXAMPLES

122       route add -net 127.0.0.0 netmask 255.0.0.0 metric 1024 dev lo
123              adds  the  normal  loopback  entry,  using netmask 255.0.0.0 and
124              associated with the "lo" device (assuming this device was previ‐
125              ously set up correctly with ifconfig(8)).
126
127
128       route add -net 192.56.76.0 netmask 255.255.255.0 metric 1024 dev eth0
129              adds  a  route to the local network 192.56.76.x via "eth0".  The
130              word "dev" can be omitted here.
131
132
133       route del default
134              deletes the current default route, which is labeled "default" or
135              0.0.0.0 in the destination field of the current routing table.
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137
138       route add default gw mango
139              adds  a  default  route  (which  will  be used if no other route
140              matches).  All  packets  using  this  route  will  be  gatewayed
141              through  the  address  of a node named "mango". The device which
142              will actually be used for that route depends on how we can reach
143              "mango" - "mango" must be on directly reachable route.
144
145
146       route add mango sl0
147              Adds  the route to the host named "mango" via the SLIP interface
148              (assuming that "mango" is the SLIP host).
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150
151       route add -net 192.57.66.0 netmask 255.255.255.0 gw mango
152              This command adds the net "192.57.66.x" to be gatewayed  through
153              the former route to the SLIP interface.
154
155
156       route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
157              This  is  an obscure one documented so people know how to do it.
158              This sets all of the class D (multicast) IP  routes  to  go  via
159              "eth0".  This  is  the  correct normal configuration line with a
160              multicasting kernel.
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162
163       route add -net 10.0.0.0 netmask 255.0.0.0 metric 1024 reject
164              This  installs  a  rejecting  route  for  the  private   network
165              "10.x.x.x."
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167
168       route -6 add 2001:0002::/48 metric 1 dev eth0
169              This  adds a IPv6 route with the specified metric to be directly
170              reachable via eth0.
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172

OUTPUT

174       The output of the kernel routing table is organized  in  the  following
175       columns
176
177       Destination
178              The destination network or destination host.
179
180       Gateway
181              The gateway address or '*' if none set.
182
183       Genmask
184              The  netmask  for  the  destination net; '255.255.255.255' for a
185              host destination and '0.0.0.0' for the default route.
186
187       Flags  Possible flags include
188              U (route is up)
189              H (target is a host)
190              G (use gateway)
191              R (reinstate route for dynamic routing)
192              D (dynamically installed by daemon or redirect)
193              M (modified from routing daemon or redirect)
194              A (installed by addrconf)
195              C (cache entry)
196              !  (reject route)
197
198       Metric The 'distance' to the target (usually counted in hops).
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200       Ref    Number of references to this route. (Not used in the Linux  ker‐
201              nel.)
202
203       Use    Count  of lookups for the route.  Depending on the use of -F and
204              -C this will be either route cache misses (-F) or hits (-C).
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206       Iface  Interface to which packets for this route will be sent.
207
208       MSS    Default maximum segment  size  for  TCP  connections  over  this
209              route.
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211       Window Default window size for TCP connections over this route.
212
213       irtt   Initial  RTT  (Round  Trip  Time). The kernel uses this to guess
214              about the best TCP protocol parameters without waiting on  (pos‐
215              sibly slow) answers.
216
217       HH (cached only)
218              The  number  of  ARP entries and cached routes that refer to the
219              hardware header cache for the cached route. This will be -1 if a
220              hardware  address  is not needed for the interface of the cached
221              route (e.g. lo).
222
223       Arp (cached only)
224              Whether or not the hardware address for the cached route  is  up
225              to date.
226

FILES

228       /proc/net/ipv6_route
229       /proc/net/route
230       /proc/net/rt_cache
231

SEE ALSO

233       ip(8)
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HISTORY

236       Route  for  Linux  was  originally  written  by  Fred  N.   van Kempen,
237       <waltje@uwalt.nl.mugnet.org> and then modified by Johannes  Stille  and
238       Linus  Torvalds for pl15. Alan Cox added the mss and window options for
239       Linux 1.1.22. irtt support and merged with netstat  from  Bernd  Ecken‐
240       fels.
241

AUTHOR

243       Currently  maintained  by Phil Blundell <Philip.Blundell@pobox.com> and
244       Bernd Eckenfels <net-tools@lina.inka.de>.
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248net-tools                         2014-02-17                          ROUTE(8)
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