Linux: Three default gateways?
- by Daniel
My server has three default gateways, how can that be? Shouldn't there be one default gw?
I have three NICs, each attached to a separate subnet:
server1:~# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.5.0.0 * 255.255.255.224 U 0 0 0 eth3
localnet * 255.255.255.224 U 0 0 0 eth0
192.168.8.0 * 255.255.255.192 U 0 0 0 eth1
default 10.5.0.1 0.0.0.0 UG 0 0 0 eth3
default 192.168.8.1 0.0.0.0 UG 0 0 0 eth1
default 10.1.0.1 0.0.0.0 UG 0 0 0 eth0
Sometimes, I can't ping a host on the Internet, sometimes I can. What I want is traffic to the Internet (0.0.0.0) routed through a specific NIC. Can I just add a route for 0.0.0.0 and default gw to one of the eth0-3 interfaces? Will it break my connection?
I'm using Debian, here is my /etc/network/interfaces:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
allow-hotplug eth0
iface eth0 inet static
address 10.1.0.4
netmask 255.255.255.224
network 10.1.0.0
broadcast 10.1.0.31
gateway 10.1.0.1
allow-hotplug eth1
iface eth1 inet static
address 192.168.8.4
netmask 255.255.255.192
network 192.168.8.0
broadcast 192.168.8.63
gateway 192.168.8.1
allow-hotplug eth3
iface eth3 inet static
address 10.5.0.4
netmask 255.255.255.224
network 10.5.0.0
broadcast 10.5.0.31
gateway 10.5.0.1
