Debian / Ubuntu Linux Setting a Default Gateway

by Vivek Gite on April 18, 2007 · 18 comments

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

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

Featured Articles:

Share this with other sys admins!
Facebook it - Tweet it - Print it -

{ 18 comments… read them below or add one }

1 Rajesh February 28, 2008: I also want to set my defualt DNS server and proxy settings, just like in windows. How do I do that ??
Reply
2 shutty July 16, 2008: 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
Reply
3 Petrus September 2, 2008: How do I add a second gateway on higher metric incase the first goes down?
Reply
4 vivek September 2, 2008: 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/
Reply
5 Mauro October 18, 2008: 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
Reply
6 vivek October 18, 2008: 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 $GW
Reply
7 Mauro October 18, 2008: vivek, many many many thanks. It works!
Reply
8 adam October 30, 2008: For two interfaces that both do dhcp the metrics on the default gateway can be added like this.
auto eth1
iface eth1 inet dhcp
metric 10
auto eth2
iface eth2 inet dhcp
metric 20
Reply
9 Kuldeep Yadav March 6, 2009: Is there any way,so that we can give proxy addresss frm command line apart from browser.because if we give this from command line,it will be applicable to all system.
Reply
10 Peter Holmes September 1, 2009: I have two interfaces, eth0 & eth1. eth0 fixed IP 192.168.1.20 hardwired to test machine with fixed IP 192.168.1.6, (not easily altered).
I want eth1 to connect to internet via a DHCP Server Router. Without eth1 enabled there is no problem but as soon as I enable eth1 as DHCP client I lose any access to 192.168.1.6
Have spent many hours altering the route(s), etc., with no success.
Do I have to use ipchains or can it be achieved with route?
Reply
11 catalin September 16, 2009: I am having some routing problems with Ubuntu 9.04:
Whenever I start up my system, the Internet won’t work unless I do:
"sudo route add default gw 192.168.1.254"
I tried to alter /etc/network/interfaces, but with no luck. After restart, it doesn’t work. executing route prints:
catalin@lolinux:~$ 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?
Reply
12 Stuart Smith October 13, 2009: 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.
Reply
13 joshlondon November 24, 2009: 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?
Reply
14 Stuart Smith November 26, 2009: I eventually removed Network Manager. Set everything up manually and it works fine.
Reply
15 Josh November 26, 2009: 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.
Reply
16 Daniel Smith March 20, 2010: How can I find Gateway server !? to add the numbers to the address code!?
Reply
17 Mahmoud Ibrahim February 20, 2011: 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.
Reply
18 Wael Hawa July 25, 2011: 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
Reply