multihomed nic's in ubuntu 8.10
 

Hi All,

I am just getting to grips with ubuntu after years of solaris. So please be patient with the newbie questions.

I have a server with 2 nic's I have no firewall enabled as yet.

my /etc/network/interfaces contains the following

# 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
auto eth0 eth1

iface eth0 inet static
address 10.18.0.1
netmask 255.0.0.0
network 10.0.0.0
broadcast 10.255.255.255
gateway 10.1.0.5
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 172.17.0.2
dns-search xxx.com

iface eth1 inet static
address 172.22.0.127
netmask 255.255.0.0
network 172.22.0.0
broadcast 172.22.255.255


the default gateway needs to be 10.1.0.5 as thats where all the traffic needs to go. (internet facing)

now when i try to connect to the 172.22.0.127 it doesnt connect me, the packets are supposed to come in on eth1 and out on eth0
a tcp dump does shows on eth1 mypc -> eth1, however on eth0 i see no packet leaving the system at all.

ip route get 172.23.0.26 shows the default gateway being 10.1.0.5 which is correct.

Is there a setting that is blocking return packets with a src address not being the interface that the packet is leaving from.

or am i missing something more fundemental.

This behaviour works out of the box on the solaris boxes we are replacing with ubuntu.

Thanks in advance for any light that can be shed on this

regards

Tony Mills

hmm, correct me if im wrong but you are trying to configure the machine to route traffic requests from internal network eth1 to internet facing interface eth0? such as you have a lan plugged into eth1 and your internet connection on eth0?
there is a gui called firestarter
http://www.fs-security.com/
that might help ;)