Multiple Gateway for a linux server

kssuhesh · 01-29-2015, 03:42 AM

Hello,

Is it possible to set multiple gateway to one linux system, so that I can use one for communicate with multiple private networks (172.16.0.0/24, 172.16.1.0/24) and one for internet ?

QYInst · 01-29-2015, 07:39 PM

Quote:

Originally Posted by kssuhesh

Hello,
Is it possible to set multiple gateway to one linux system, so that I can use one for communicate with multiple private networks (172.16.0.0/24, 172.16.1.0/24) and one for internet ?

Yes, it is possible. This is what route is for.
You can have not only multiple gateways, but also multiple devices.

Let us say, you want to access the private networks through gateway X.X.X.X, device ethA, and internet through gateway Y.Y.Y.Y, device ethB.
You may want to delete the default route rule first. By executing

Code:

$ route -n

You may find a line like

Code:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0               Z.Z.Z.Z             0.0.0.0              UG     0            0        0      ethC

You can delete it with

Code:

# route del -net 0.0.0.0 netmask 0.0.0.0 dev ethC

Then you just need to add the following routes

Code:

# route add -net 172.16.0.0 netmask 255.255.255.0 gw X.X.X.X dev ethA
# route add -net 172.16.1.0 netmask 255.255.255.0 gw X.X.X.X dev ethA
# route add -net 0.0.0.0 netmask 0.0.0.0 gw Y.Y.Y.Y dev ethB

Remember to replace X/Y/Z and A/B/C according to your real configuration.