Comments on: Red Hat / CentOS Linux Setting a Default Gateway

By: Vivek Gite

Vivek Gite — Tue, 17 Jan 2012 08:49:45 +0000

Your command will only work with Redhat and friends. We are talking about Debian Linux here. The correct command that will work on all debian version:

/etc/init.d/networking restart

However, the latest version of Debian such as 6.x can use the service command:

/usr/sbin/service networking restart

By: LiNDA

LiNDA — Tue, 17 Jan 2012 08:08:08 +0000

I just wondering why you don’t use command #service network restart….???

By: Ravi Saive

Ravi Saive — Wed, 21 Sep 2011 11:06:21 +0000

Nice information….

By: izack

izack — Thu, 11 Aug 2011 08:11:21 +0000

hi
i have a problem on how to configure a red had linux pc as the gateway
in a single computer with to NIC

By: Norton

Norton — Wed, 18 May 2011 17:06:20 +0000

Regarding setting the default route and Vivek’s mildly complicated solution:

In CentOS5 (at least) you can set GATEWAYDEV=eth0 in /etc/sysconfig/network, and you do not need to modify ifcfg-eth* to remove the GATEWAY definitions.

By: Allison

Allison — Sat, 14 May 2011 17:52:20 +0000

im having issues changing my server NIC from DHCP to static, i keep getting the error : “Shutting down loopback interface: [ OK ]
Bringing up loopback interface: [ OK ]
does not seem to be present, delaying initialization.
[FAILED] ”

Help will be appreciated.

By: Henrik A

Henrik A — Wed, 22 Dec 2010 02:04:11 +0000

Hi,
I am trying to set up a RHEL5 box with two nic’s.
eth2 is connected to the internet
eth3 is connected to a firewall that runs our lan and has a IPSec connection to a customer.

My problem is this.
When I try to start up eth3 it is automatically assigned a default gateway, which is the same as for eth2. So when I try to set a static route i get “RTNETLINK answer: file exists” because it already has a gateway.

ifcfg-eth3:

# Intel Corporation 82571EB Gigabit Ethernet Controller
DEVICE=eth3
BOOTPROTO=none
HWADDR=00:15:17:8C:7F:1B
ONBOOT=yes
TYPE=Ethernet
USERCTL=no
IPV6INIT=no
PEERDNS=yes
NETMASK=255.255.255.0
IPADDR=192.168.2.99

route-eth3:
192.168.2.0/24 via 192.168.2.254
10.212.1.0/24 via 192.168.2.254

the resulting route table:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
xxx.xxx.xxx.xxx 0.0.0.0 255.255.255.248 U 0 0 0 eth2
10.212.1.0 192.168.2.254 255.255.255.0 UG 0 0 0 eth3
192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 eth3
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth3
0.0.0.0 xxx.xxx.xxx.xxx 0.0.0.0 UG 0 0 0 eth2

The destination 192.168.2.0 should have the gateway 192.168.2.254

Any ideas on how to get this working?

By: Vivek Gite

Vivek Gite — Wed, 05 May 2010 01:31:07 +0000

You can add hook to network service or better configure static routing :) this will take care of service network restart command. HTH

By: Colin

Colin — Wed, 05 May 2010 00:23:24 +0000

/etc/rc.local
route add -net netmask gw eth0
route add -net netmask gw eth1
route add default gw eth0

This is the way I would imagine doing it myself. but what happens after a services network restart

By: MadMac66

MadMac66 — Mon, 22 Feb 2010 09:10:10 +0000

Hi,
if possible, simply edit /etc/rc.local and add all the routings you want.
There you can setup specific routings for specific NICs and of course also the Default Gateway. example:
route add -net netmask gw eth0
route add -net netmask gw eth1
route add default gw eth0

this way you can setup are more complex routing.

By: bobby

bobby — Thu, 04 Feb 2010 04:23:36 +0000

How to add specific route for another network

By: bobby

bobby — Wed, 03 Feb 2010 09:31:25 +0000

Dear Vivek,can u please more brief on Nics,i have 2 networks and 2 lans total 4 lan ports,
now i have 2 difrnt n/w coming from single cable,(IT N/w,signaling N/w),and both n/w have diffrent Gateways.i can not add gateways in /etc/sysconfig/network-script/ifcfg-eth0 and eth1,in /etc/sysconfig/network i have added gateway of signaling..

now i can ping at signaling n/w but not IT network?how to add gateway for another network

By: DunxD

DunxD — Wed, 21 Oct 2009 10:36:11 +0000

You don’t want multiple default gateways, else you will get intermittent networking problems!

What you want is one default gateway, then if you need specific routes for specific subnets you should set those up as required.

Restart network is also available on RHEL and CentOS by services network restart

By: Raghavan alias Saravanan M

Raghavan alias Saravanan M — Wed, 16 Sep 2009 14:42:41 +0000

Hi there,

Yours is a good site and have found useful at various places and searches.

Thanks for the efforts and keep up the good work :)

The way you restart the service, should NOT it be ‘/etc/init.d/network’ instead of ‘networking’? Just check that out.

Cheers,
Raghavan alias Saravanan M.

By: jamie

jamie — Tue, 21 Apr 2009 14:54:34 +0000

route add -net 192.168.60.0 netmask 255.255.255.0 gw 192.168.30.1
route add -net 192.168.30.0 netmask 255.255.255.0 gw 192.168.30.1

This forces all traffic through my 30 subnets gateway, which is 192.168.30.1.

By: spiderik

spiderik — Mon, 20 Apr 2009 18:59:33 +0000

But I have eth0 and eth1 under DHCP and I need the eth0 to be the default gw / any hints?

By: Rudy

Rudy — Thu, 29 Jan 2009 01:13:50 +0000

BiOg is right in that if you have multiple interfaces it will pick the last one. The fix to that is pretty much what vivek said.
Set your default gateway in the /etc/sysconfig/network and make sure none of the interface /etc/sysconfig/network-scripts/ifcfg- files have a “GATEWAY” line in them. That will force the system to pick the default GW from the network file. You can set static routes in the /etc/sysconfig/network-scripts/route- files

By: vivek

vivek — Sat, 15 Nov 2008 04:18:57 +0000

Open /etc/sysconfig/network and append
GATEWAY=eth0.gateway.IP.address

Open /etc/sysconfig/network-scripts/route-eth1 and add routing for eth1 and restart it. For example:
202.54.1.2/29 via 202.54.2.254

Also, set static route for /etc/sysconfig/network-scripts/route-eth0:
10.1.2.3/8 via 10.10.38.95

Do not add gateway entries to
/etc/sysconfig/network-scripts/ifcfg-eth1 and /etc/sysconfig/network-scripts/ifcfg-eth0

By: BiOg

BiOg — Fri, 14 Nov 2008 21:39:22 +0000

With 2 (or more) NIC I notice that the default gateway is always set to the last NIC.

I.E: if you have eth0 and eth1 and configure you default gateway via /etc/sysconfig/network, /etc/sysconfig/network-scripts/ifcfg-eth* and event tweak the routes via /etc/sysconfig/network-scritps/route-eth* and /etc/sysconfig/static-routes to have the default be on eth0

It still end up being the eth1 network used as the default route (shown by the route command).

The script executed during the boot just goes through all the interface configuration and then set the default route on the last visited interface; trashing previous settings (go figure why).

Somebody suggested to me that there is a way to select the default device (or interface) but I am yet to find a good hit on Google.

By: wizkidno

wizkidno — Thu, 29 Nov 2007 13:39:14 +0000

If you only do the editing in the /etc/network/interfaces file they will be overwritten at boot time.
Please edit /etc/sysconfig/network as described in the article as well.

You can allso set the gateway on each device by editing :
vim /etc/sysconfig/networking/devices/ifcfg-eth0
vim /etc/sysconfig/networking/devices/ifcfg-eth1
And changing the gateway declaration.

Alternativly you could use the util :
system-config-network (from both command line and X.)