41

What command can you use to find the Gateway IP Address (ie. home router address) for eth0 in Linux?

I need to get the IP address from a command line app to use in a shell script.

J. Polfer
  • 679

12 Answers12

48

To print out only the default gw IP:

route -n | grep 'UG[ \t]' | awk '{print $2}'

To print out route information on all interfaces:

route -n

or

netstat -rn
Benjamin Loison
  • 140
l0c0b0x
  • 12,187
34
ip route show 0.0.0.0/0 dev eth0 | cut -d\  -f3

is my entry :)

MikeyB
  • 40,079
6

You can get the system's default gateway from the output of netstat -r or route

Kamil Kisiel
  • 12,444
6
$ netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
192.168.199.0   0.0.0.0         255.255.255.240 U         0 0          0 virbr1
192.168.200.0   0.0.0.0         255.255.255.240 U         0 0          0 virbr2
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 wlan0
192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0
0.0.0.0         192.168.1.254   0.0.0.0         UG        0 0          0 wlan0

The 0.0.0.0 is your default gateway, pointing to 192.168.1.254 at my place.

wzzrd
  • 10,589
5

Since iproute2 4.14.1, you can also output JSON for a lot of commands.

So this would work:

ip -j route show 0.0.0.0/0 dev <interface> | jq -r '.[0].gateway'

In your case:

ip -j route show 0.0.0.0/0 dev eth0 | jq -r '.[0].gateway'

Note that you need jq for this, but depending on your environment that might already be available - I know it was in my case.

Benjamin Loison
  • 140
href_
  • 181
4

I prefer the iproute package:

# get the default route
ip route list | awk ' /^default/ {print $3}'
# get the default route but limit on eth0 (output may be empty)
ip route list dev eth0 | awk ' /^default/ {print $3}'
Benjamin Loison
  • 140
serverhorror
  • 6,538
4

anyone shorter than this? =)

ip r | awk '/^def/{print $3}'
ThorstenS
  • 3,170
2

The output from route -n or netstat -rn, and search for the destination 0.0.0.0.

TCampbell
  • 2,054
1

If you would like to get the gateway from the interfaces file:

#!/bin/bash
gateway=$(grep -P '^\tgateway' /etc/network/interfaces)
gateway=$(echo ${gateway:9})    # Remove "  gateway "   
echo "gateway = $gateway"
if [ $gateway == "" ]; then
    echo "gateway is blank"
    exit -1
fi
Benjamin Loison
  • 140
xinthose
  • 174
0
netstat -rn |awk '{if($1=="0.0.0.0") print $2}'

this will cleanly print the gateway IP. (what would linux scripting be without awk?)

Benjamin Loison
  • 140
0

My one liner command to get the default gateway IP address :

route | grep default | awk '{print $2}'
sys0dm1n
  • 111
-2

Open Terminal on your Linux OS It’s usually located in the top bar or bottom bar, depending on the Linux distribution you use Once you have opened the Terminal window, enter the following commands “ip route | grep default” Now wait a second for the output and note your default gateway address on the screen Your gateway address should look something like 192.168.1.1. Once you know it, you can start configuring your router via its web admin panel.

If this didn't fix your network, you may need a new router.

Sven
  • 100,763
Asif Mumtaz
  • 1