Setting up linux routing

Question

The system I'm trying to set up has an IP address 172.31.2.1. Its default gateway is 172.31.254.1. This works fine, and I can reach anything the gateway allows me to go to (172.31.0.0/16 + 149.244.178.0/24).

There is another gateway at 149.244.178.1 which will allow me to reach anything in 149.244.0.0, and I'm trying to add that to the table so I can access 149.244.64.250.

This is what my routing table currently looks like:

Kernel IP Routing table
Destination    Gateway      Genmask      Flags    Metric    Ref    Use    Iface
172.31.0.0     *            255.255.0.0  U        0         0        0    eth0
169.254.0.0    *            255.255.0.0  U        0         0        0    eth0
default        172.31.254.1 0.0.0.0      UG       0         0        0    eth0

route add 149.244.0.0/16 gw 149.244.178.1 gives the error:

route: netmask 0000ffff doesn't make sense with host route.

route add -net 149.244.0.0/16 dev eth0 changes the route table to:

Kernel IP Routing table
Destination    Gateway      Genmask      Flags    Metric    Ref    Use    Iface
172.31.0.0     *            255.255.0.0  U        0         0        0    eth0
169.254.0.0    *            255.255.0.0  U        0         0        0    eth0
149.244.0.0    *            255.255.0.0  U        0         0        0    eth0
default        172.31.254.1 0.0.0.0      UG       0         0        0    eth0

However, trying to add the gateway still gives me the same error. Sorry if it sounds convoluted, and any help is appreciated!

Solution

The 149.x.x.x host wouldn't be on your local subnet, so your computer would have no way of contacting it. A router between your subnet and that subnet should have both a 149.x and a 172.x address (on two different NICs hopefully), it would route between the two subnets.

Comments

[Zoredache]

Or to put it a different way. Your routes always should specify a gateway on the directly attached networks that will be the next hop.

[Sagar]

Ok. I thought that was the case, but was hoping against hope. Oh well.