Adding Static Routes On Various *NIX (Linux,AIX,HP-UX)

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Static routes are generally required for  traffic that must not, or should not, go through the default gateway. In this article we will discuss how to add static routes in variox nix.

Scenario : Suppose if you want that all the traffic to network 172.168.102.0/24 should use 172.168.101.1 as gateway. This can be done by adding a static route in the kernel routing table as shown below.

Adding Static Route in Linux from the Command line :

# route add -net 172.168.102.0 netmask 255.255.255.0 gw 172.168.101.1 dev eth0

OR

# ip route add 172.168.102.0/24 via 172.168.101.1 dev eth0

Above Commands will make changes to the routing table temporary and not permanent. Use any of below mention command To check Routing tables in Linux :

# route -n
# netstat -nr

Steps to make the static Route Persistent Across the reboot :

In case of RHEL5.X / CentOS 5.X

Create a file  route file

# vi /etc/sysconfig/network-scripts/route-eth0

172.168.102.0/24 via 172.168.101.1 dev eth0

Save and close the file and  Restart network service

# service network restart

In case of RHEL6.X / CentOS 6.X

# vi /etc/sysconfig/network-scripts/route-eth0

GATEWAY0= 172.168.101.1
NETMASK0=255.255.255.0
ADDRESS0= 172.168.102.0

Save and close the file and  Restart network service

# service network restart

Adding Static Routes in AIX :

Step:1 Go to the SMITTY menu for routes

Step:2 Select Type of route 'net' or 'host' ( if default route then leave set to 'net' )

Step:3 Enter  the destination address.

Step:4 Enter the gateway address ( on the line that “* default GATEWAY Address")

Step:5 If a 'net' or default route , enter the 'Network Mask' , if host  do not set 'Network Mask'

Step:6 Enter the network interface for this route. To select from the list arrow down to the 'Network Interface' line and hit [F4] or [ESC]+ [4]   to display list of available interfaces.

Step:7 Hit [ENTER] TO APPLY . You should recieve a return status of “OK"

Step:8 To exit the smitty , type  [F10] or [0]

Step:9 Verify that your routes have been configured

# netstat -nr | grep UG

Adding Static Route in HP-UX

Step:1 Make a backup copy of '/etc/rc.config.d/netconf'

Step:2 Add a stanza  to /etc/rc.config.d/netconf for the new route . Make sure you use a new array number for the stanza

Example : Replace 'nn' with the next number in the list.

ROUTE_DESTINATION[nn]="IP-of-NewHost"
ROUTE_MASK[nn]=" “
ROUTE_GATEWAY[nn]="IP-of-Router"
ROUTE_COUNT[nn]=""
ROUTE_ARGS[nn]=""

Save  & Close the file

Step:3 Now run the below command to re-read the netconf file and add the route

# /sbin/init.d/net start

Note: Run the above command with start option only because it will add new route without effecting existing network configuration.