So I have a little test linux vps setup with ubuntu. I want to find out how to browse the internet (ports 80 and 443) and specify which network interface is used.

Ideally, I'd be able to run a bash command to change which interface is used. So the default is eth0. I want to use eth1 though and not interact at all with eth0. Later on though, I'll want to run eth0 and not interact with eth1.

Other than ifconfig up and ifconfig down, how can I do this?

-Thanks

Are all eth0-eth3 configured on the same subnet and connected to the default gateway? Or do you just want to set an IP for one of those so that it can reach the router?

jlinkels

The thing is that I ssh into the vps, so I'd like to be able to do this without getting disconnected by an ip change. All are connected to the default gateway.

I'd like to something like: Run a script for eth0.sh. Then all web browsers go out as eth0's ip address. Then I could run eth1.sh and all web browsers go out as eth1's ip address

I haven't tested it, but I can imagine it is something like:
And change it with:
You might have to delete the existing default gw first.
If you are connected on the same subnet this should not break your SSH connection. Then the box doesn't need a default gw to get back to you.

jlinkels

Guess you could set metric on them too.

When I do a route -n, it says the gateway is 0.0.0.0 as well as destination and genmask.

So I tried your command:

sudo route add default gw 0.0.0.0 eth1

and I got SIOCADDRT: Invalid argument

The default gateway must be something on the same subnet as the network interface. So configure the network interface correctly, then set the default gw to something on the same subnet.

And study the route command. If you want to make a setup like this (why do you want that anyway?) you might want to understand what the idea behind routes is.

jlinkels

Ok, I am very lost. I can't find my route -n results anywhere on the internet. Here is my /etc/network/interfaces file. Maybe that will help. IP addresses have been changed though.

# Auto generated lo interface
auto lo
iface lo inet loopback

# Auto generated venet0 interface
auto venet0
iface venet0 inet manual
up ifconfig venet0 up
up ifconfig venet0 127.0.0.2
up route add default dev venet0
down route del default dev venet0
down ifconfig venet0 down


iface venet0 inet6 manual
up route -A inet6 add default dev venet0
down route -A inet6 del default dev venet0

auto venet0:0
iface venet0:0 inet static
address 10.10.13.12
netmask 255.255.255.255

auto venet0:1
iface venet0:1 inet static
address 10.10.13.136
netmask 255.255.255.255

auto venet0:2
iface venet0:2 inet static
address 10.10.13.15
netmask 255.255.255.255

auto venet0:3
iface venet0:3 inet static
address 10.10.13.13
netmask 255.255.255.255

auto venet0:4
iface venet0:4 inet static
address 10.10.13.14
netmask 255.255.255.255


-Thanks

I think I figured it out. I can run this command to change the route:

sudo route add -net 0.0.0.0/0 dev venet0:3

That changes my ip to show that of the venet0:3 card. Then I can do a "sudo route del default" to change it back to the default.

Thanks for the help. It got me in the right direction.