Tag: IP

Display default route

The following three commands display the current routing table:

# route

Output:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     *               255.255.255.0   U     0      0        0 ra0
default         dsl-router      0.0.0.0         UG    0      0        0 ra0

# /sbin/route

Output:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
191.255.255.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
default         191.255.255.1   0.0.0.0         UG    0      0        0 eth0

You can use -n option, to display numerical addresses instead of trying to determine symbolic host names (via dns or /etc/hosts file). This is useful if you are trying to determine why the route to your nameserver has vanished.$

#/sbin/route -n

Output:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
191.255.255.0   0.0.0.0         255.255.255.0   U     0      0        0 venet0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 venet0
0.0.0.0         191.255.255.1   0.0.0.0         UG    0      0        0 venet0

 

Please note that a destionation entry 0.0.0.0 (or default) is the default gatway. In above example 191.255.255.1 is a default gatway.

Add / setup a new route

The syntax is as follows:
route add default gw {IP-ADDRESS} {INTERFACE-NAME}

Where,

• IP-ADDRESS: Specify router IP address
• INTERFACE-NAME: Specify interface name such as eth0

For example if your router IP address is 192.168.1.254 type the following command as the root user:

# route add default gw 192.168.1.254 eth0

OR use hostname such as dsl-router:

# route add default gw dsl-router eth0

Setting route using GUI tools/command under Linux

If you find above command hard to use, consider using GUI tools. If your are using Red Hat/CentOS/Fedora core Linux type following command:

# redhat-config-network

OR

If you are using other Linux distribution use command:

# network-admin