ROUTES(5) Network configuration ROUTES(5)NAMEroutes - configure the routing table
SYNOPSIS
/etc/sysconfig/network/routes
/etc/sysconfig/network/ifroute-*
DESCRIPTION
The files /etc/sysconfig/network/routes and /etc/sysconfig/net‐
work/ifroute-config are parsed by the script /etc/sysconfig/net‐
work/scripts/ifup-route which sets up routing for an interface/configu‐
ration. ifup-route is used by /sbin/ifup, which is the command line
user interface for setting up network interfaces.
/etc/sysconfig/network/routes is used for every interface while
/etc/sysconfig/network/ifroute-config is used only for the network
interface configuration stored in /etc/sysconfig/network/ifcfg-config,
that means only for a certain interface. (See a discussion of the
notions configuration, interface and device in ifup(8).)
At boot time /etc/init.d/network calls ifup for every existing configu‐
ration and uses ifup-route directly to set up special routes which do
not belong to a certain interface.
The current routes can be seen by issuing:
/sbin/ip route list
which will give the current routing table.
Syntax
The files /etc/sysconfig/network/routes and /etc/sysconfig/net‐
work/ifroute-config use the same syntax. The only difference is the
interpretation of an empty interface field. See 4th column below.
Lines beginning with # and blank lines are ignored. There are 5 columns
with special meaning. Write a dash "-" if you want to omit an entry
for a field. If all following fields in the line are empty too, you can
even omit the dash.
The first column gives the destination, written as the IP-address of a
host or a network. The heading default indicates that the route is the
default gateway. Do not use 0.0.0.0 for this purpose. A prefix-length
(CIDR notation) can be used; e.g., 10.10.0.0/16 and also 10.10/16 are
valid.
The second column contains the gateway. Write here the regular IP-
address of a host which routes the packets to a remote host or remote
network. You can omit this information for rejecting routes.
The third column gives the netmask for a remote host or remote network
behind a gateway. For the default route or if you were using a prefix-
length (CIDR notation) in the first column, you can omit it.
The fourth column gives the name of the interface of the local networks
(lo, eth0, eth1, isdn0, ppp0, dummy0, ...).
If you leave this field empty the result depends on the file you are
using. In /etc/sysconfig/network/routes the field is interpreted as no
interface information available. That is sufficient for the most routes
you may set up, but if you have multiple interfaces this route is set
up with every single interface you activate. This may lead to error
messages in the syslog. If you see such an error message which tells
you "... this needs NOT to be AN ERROR" then check if you wrote the
wrong ip addresses or if it occurs because it's being set up with the
wrong interface.
In the latter case you may want to use /etc/sysconfig/network/ifroute-
config instead. Here an empty interface field is always replaced with
the interface name that is currently being activated. This makes sense
because this file is only used for one configuration (for one inter‐
face).
Note:
Static routes without explicit interfaces will also replace routes to
the same destination (network) configured by dhcp clients on any inter‐
face!
Static routes with explicit interface will also replace routes to the
same destination (network) configured by dhcp clients on this inter‐
face.
The fifth column can be used to specify the type of a route:
unicast
The route entry describes real paths to the destinations covered
by the route prefix.
local The destinations are assigned to this host. The packets are
looped back and delivered locally.
broadcast
The destinations are broadcast addresses. The packets are sent
as link broadcasts.
multicast
A special type used for multicast routing. It is not present in
normal routing tables.
throw A special control route used together with policy rules. If such
a route is selected, lookup in this table is terminated pretend‐
ing that no route was found. Without policy routing it is equiv‐
alent to the absence of the route in the routing table. The
packets are dropped and the ICMP message net unreachable is gen‐
erated. The local senders get an ENETUNREACH error.
unreachable
These destinations are unreachable. Packets are discarded
silently. The local senders get an EINVAL error.
prohibit
These destinations are unreachable. Packets are discarded and
the ICMP message communication administratively prohibited is
generated. The local senders get an EACCES error.
blackhole
These destinations are unreachable. Packets are discarded
silently. The local senders get an EINVAL error.
nat A special NAT route. Destinations covered by the prefix are con‐
sidered to be dummy (or external) addresses which require trans‐
lation to real (or internal) ones before forwarding. The
addresses to translate to are selected with attribute 'via'.
Any remaining columns, if given, are appended to the route command.
This makes it possible to pass special options for this route. Columns
which are not needed should contain a minus sign ( - ) to ensure that
the parser correctly interprets the command.
EXAMPLES
An example with common network interfaces and some static routes:
# Destination Dummy/Gateway Netmask Interface
#
127.0.0.0 0.0.0.0 255.255.255.0 lo
204.127.235.0 0.0.0.0 255.255.255.0 eth0
default 204.127.235.41 0.0.0.0 eth0
207.68.156.51 207.68.145.45 255.255.255.255 eth1
192.168.0.0 207.68.156.51 255.255.0.0 eth1
# --- same routes as above in CIDR notation:
# Destination [Gateway] - Interface
127.0.0.0/8 - - lo
204.127.235.0/24 - - eth0
default 204.127.235.41 - eth0
207.68.156.51/32 207.68.145.45 - eth1
192.168.0.0/16 207.68.156.51 - eth1
# --- IPv6 routes are always using CIDR notation:
# Destination [Gateway] - Interface
2001:DB8:100::/64 - - eth0
2001:DB8:100::/32 fe80::216:3eff:fe6d:c042 - eth0
An example for routing entries for synchronous ppp over a ISDN connec‐
tion.
# Destination Dummy/Gateway Netmask Interface
#
127.0.0.0 0.0.0.0 255.255.255.0 lo
193.102.150.13 0.0.0.0 255.255.255.255 ippp0
default 193.102.150.13 0.0.0.0 ippp0
Note:
Routes to directly connected network are created automatically (Linux
kernel 2.4 and later) as soon as the IP address is assigned to the
interface. For example, when the eth0 interface IP addresses are
204.127.235.42/24 and 2001:DB8:100::42/64, the following routes from
above examples are created automatically:
204.127.235.0/24 - - eth0
2001:DB8:100::/64 - - eth0
and should be omitted.
NOTES
SuSE Linux >= 8.0 uses the ip command from the iproute2 package to set‐
up the network and routes. Please see the documentation distributed
with this package for more information.
FILES
/etc/sysconfig/network/routes
/etc/sysconfig/network/ifroute-config
AUTHOR
Michal Svec <msvec@suse.cz>
Christian Zoz <zoz@suse.de>
Mads Martin Joergensen <mmj@suse.de>
Thanks to Werner Fink <werner@suse.de> for the old route.conf(5).
Parts of the ip reference by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
were also used.
SEE ALSOinit.d(7), init(8), inittab(5), the documentation for the iproute2
package and the SuSE Linux handbook, chapter The SuSE boot concept.
sysconfig January 2003 ROUTES(5)
