Routing

2009-08-21T16:36:03Z

129.57.166.11:

'''Solaris''': routing can be checked by command:

netstat -nr

To check traffic for example on 'e1000g1' interface type following command, it will show every 2 seconds:

netstat -I e1000g1 -i 2

For example on ''clondaq2'' it shows following:

Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
129.57.68.0 129.57.68.24 U 1 6 e1000g1
129.57.69.0 129.57.69.202 U 1 3 e1000g2
129.57.167.0 129.57.167.109 U 1 546 e1000g0
129.57.16.0 129.57.68.100 UG 1 4
224.0.0.0 129.57.167.109 U 1 0 e1000g0
default 129.57.167.99 UG 1 356
127.0.0.1 127.0.0.1 UH 5 180 lo0

In that example traffic was routed to subnet 16 to serve SILO. It was achieved by script ''/etc/rc3.d/S99manualroute'' with following contents:

#!/sbin/sh
#
# This script adds a manual route to force traffic to the 16 net
# out the NIC that is on the 129.57.68.x lan.
# - P. Letta 04/06/2006
case "$1" in
start)
/usr/sbin/route add -net 129.57.16.0 -netmask 255.255.252.0 129.57.68.100
/usr/sbin/route add -net 129.57.166.0 -netmask 255.255.255.0 129.57.68.100
;;
stop)
;;
*)
echo "Usage: $0 { start }"
exit 1
;;
esac
exit 0

'''Linux''':

== from web ==

If you know there is always going to be a permanent route for a destination then a static route can be a viable option.To add a persistent static route in Redhat Enterprise Linux create a file called route-<int>X in the directory
/etc/sysconfig/network-scripts/
where <int> is the interface number and X is the interface number. As you would expect, these are specified in seperate file for each of the available interface. Example:
/etc/sysconfig/network-scripts/route-eth0
/etc/sysconfig/network-scripts/route-eth1
Every entry or a route has three entities as follows:
GATEWAY<N>=xxx.xxx.xxx.xxx
NETMASK<N>=yyy.yyy.yyy.yyy
ADDRESS<N>=zzz.zzz.zzz.zzz
As the names implies, they are the gateway IP, Netmask and the IP/Network Address. Note the <N> next to each of the three entities. This number defines the route entry number and should be the same on all the entities. Example:
GATEWAY0=192.168.1.1
NETMASK0=255.255.255.0
ADDRESS0=10.10.10.0

GATEWAY1=192.168.1.1
NETMASK1=255.255.255.0
ADDRESS1=20.20.20.2

A sample file /etc/sysconfig/static-routes is available for your reference.

Once the file is created, restart the network service as follows:

# service network restart

To view the routes type

# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
192.168.2.0 * 255.255.255.0 U 0 0 0 eth1
10.10.10.0 * 255.255.255.0 U 0 0 0 eth0
20.20.20.2 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth1
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

or

# ip route show
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.1
192.168.2.0/24 dev eth1 proto kernel scope link src 192.168.2.1
10.10.10.0/24 via 192.168.1.1 dev eth0
20.20.20.2/24 via 192.168.1.1 dev eth0
default via 192.168.1.1 dev eth0

To dynamically add a route, try the folowing:

Syntax:
# ip route add <Net/IP>/<Mask> via <Gateway> dev <Int>X

Example:
# ip route add 10.10.10.0/24 via 192.168.1.1 dev eth0

or

Syntax:
# route add [-net|-host] <IP/Net> netmask <Mask> gw <Gateway IP> dev <Int>X

Example:
# route add -net 10.10.10.0 netmask 255.255.255.0 gw 192.168.1.1 dev eth0

== advise ==

Specify two gateways for two network destinations: (i.e. one external, one internal private network. Two routers/gateways will be specified.)
Add internet gateway as before: route add default gw 201.51.31.1 eth0
Add second private network: route add -net 10.0.0.0 netmask 255.0.0.0 gw 192.168.10.254 eth0

See more [http://www.yolinux.com/TUTORIALS/LinuxTutorialNetworking.html here].

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Routing