Debian / Ubuntu Linux Setting a Default Gateway

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Q. How do I setup a default gateway on Debian or Ubuntu Linux? My router IP is 192.168.1.254 and I’d like to setup this as a default gateway for Debian Linux.

A. You can use command line tool such as
a] ip command – show / manipulate routing, devices, policy routing and tunnels

b] route command – show / manipulate the IP routing table

c] Save routing information to a configuration file so that after reboot you get same default gateway.

ip command to set a default router to 192.168.1.254

Login as the root and type:
# ip route add default via 192.168.1.254
OR
$ sudo ip route add default via 192.168.1.254

route command to set a default router to 192.168.1.254

Login as the root and type:
# route add default gw 192.168.1.254
OR
$ sudo route add default gw 192.168.1.254

Save routing information to a configuration file /etc/network/interfaces

Open /etc/network/interfaces file
# vi /etc/network/interfaces
OR
$ sudo vi /etc/network/interfaces
Find eth0 or desired network interface and add following option
gateway 192.168.1.254
Save and close the file. Restart networking:
# /etc/init.d/networking restart
OR
$ sudo /etc/init.d/networking restart

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

24 comment

    1. Rajesh,

      In Ubuntu, you can either add the ‘nameserver’ lines in /etc/resolv.conf like “shutty” shows, or use the recommended method in Ubuntu Precise (12.04 LTS) by adding “dns-nameservers ” and “dns-search ” in /etc/network/interfaces, like so:

      # The primary network interface
      auto eth0
      iface eth0 inet static
      address 192.168.3.1
      netmask 255.255.255.0
      # dns-* options are implemented by the resolvconf package, if installed

      dns-nameservers 8.8.8.8
      dns-search lab.internal

  2. Rajesh,

    for dns, edit file /etc/resolv.conf and add lines
    nameserver 1.1.1.1
    nameserver 2.2.2.2
    (where 1.1.1.1 and 2.2.2.2 are your nameservers)

    for proxy, use your browser configuration

  4. Petrus,

    You need to install routed and configure /etc/gateway. Another recommended option is install zebra / Quagga server and configure it. Both allows you to define and configure various routing parameters including metric.

    http://www.quagga.net/

  5. How can I get (in a variable) the current default gateway? Is there a sort of “default gateway enviroment variable” that I can read?
    Thanks

  6. Run following to display default gateway:
    ip route show | grep default | awk '{ print $3}'
    Use following to store gateway IP in a variable called GW:
    GW=$(ip route show | grep default | awk '{ print $3}')
    echo $GW

  8. For two interfaces that both do dhcp the metrics on the default gateway can be added like this.

    auto eth1
    iface eth1 inet dhcp
    metric 10

    auto eth2
    iface eth2 inet dhcp
    metric 20

  9. Is there any way,so that we can give proxy addresss frm command line apart from browser.because if we give this from command line,it will be applicable to all system.

  10. I have two interfaces, eth0 & eth1. eth0 fixed IP 192.168.1.20 hardwired to test machine with fixed IP 192.168.1.6, (not easily altered).
    I want eth1 to connect to internet via a DHCP Server Router. Without eth1 enabled there is no problem but as soon as I enable eth1 as DHCP client I lose any access to 192.168.1.6
    Have spent many hours altering the route(s), etc., with no success.
    Do I have to use ipchains or can it be achieved with route?

  11. I am having some routing problems with Ubuntu 9.04:
    Whenever I start up my system, the Internet won’t work unless I do:
    "sudo route add default gw 192.168.1.254"
    I tried to alter /etc/network/interfaces, but with no luck. After restart, it doesn’t work. executing route prints:

    catalin@lolinux:~$ 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 wlan0

    After I manually add the gateway, everything is fine, and route prints another gateway:

    catalin@lolinux:~$ 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 wlan0
    default dsldevice.lan 0.0.0.0 UG 0 0 0 wlan0

    Is there any difference from what I altered and the kernel routing table? If there is, how do I modify that? Or would a startup script be a better solution?

  12. I have the “gateway 192.168.1.1” in my network file but I’m still required to manually set the route after reboot. This behavior began only after I “bonded” my two NIC’s. The routing table before the manual route command shows
    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use Iface
    192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 bond0
    192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth1
    192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
    0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth1
    0.0.0.0 192.168.1.1 0.0.0.0 UG 100 0 0 bond0
    and after adds this one line just below the 169.254… line
    0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 bond0

    Am I missing something or am I experiencing a true bug?

    I’m using Kubuntu 9.04 Jaunty.

  13. I am having the same problem..I have to manually set my default gateway after each boot up even though all my network settings include it. How do I get it to stick?

  15. I just switched to static ip’s and set everything through wicd..works perfectly. Also I used the network admin tool and I believe that screwed up lots of things.

  17. How can i use 2 gateway , I have a complex network using 2 ISP and Linux as a cache and firewall and a router.

    i WANT lINUX router to be able to use both ISP in same time and could nat global IP.

  18. I am using my nanostation 5 as a router… but I can’t receive ping from the ISP gateway… even though I have my ip in the same range. I found this site but the GW isn’t adding… Here are my tables

    Destination Gateway Genmask Flags Metric Ref Use Iface
    10.64.64.64 * 255.255.255.255 UH 0 0 0 ppp0
    10.29.136.0 * 255.255.255.0 U 0 0 0 eth0
    169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
    default * 0.0.0.0 U 0 0 0 ppp0

    My ip range is 10.29.136.0… I need to add 10.29.136.1 as GW

  19. Hehe
    funny thing here! very old Debian distro, I’m trying to add new default gateway via.. tun interface (VPN), but it’s refusing to add anything :D

    ip route
    10.10.0.2 dev tun0 proto kernel scope link src 10.10.0.1
    10.1.0.0/24 via 10.10.0.2 dev tun0
    10.0.0.0/16 dev eth1 proto kernel scope link src 10.0.0.254
    192.168.0.0/16 dev eth0 proto kernel scope link src 192.168.33.100
    default via 192.168.0.1 dev eth0

    ping 10.1.0.1
    PING 10.1.0.1 (10.1.0.1) 56(84) bytes of data.
    64 bytes from 10.1.0.1: icmp_seq=1 ttl=64 time=0.726 ms
    64 bytes from 10.1.0.1: icmp_seq=2 ttl=64 time=0.544 ms
    64 bytes from 10.1.0.1: icmp_seq=3 ttl=64 time=1.60 ms
    64 bytes from 10.1.0.1: icmp_seq=4 ttl=64 time=1.58 ms

    sudo ip route add default via 10.1.0.1
    RTNETLINK answers: No such process

    sudo route add default gw 10.1.0.1
    SIOCADDRT: Nie ma takiego procesu

  21. add the following to the bottom of your /etc/network/interfaces file

    # Static route
    up route add -net xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx dev ethX

  22. I use the following commands to add a new gateway and remove an existing one :

    sudo route add default gw 192.168.12.1 eth1
    sudo route delete default gw 10.0.2.2 eth0

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