Need to setup Linux box as a forwarding router

[markwombat]

Hi people,

Hopefully you can help me here without too much hassle, I am pretty sure its an easy request but I'm only just starting out Linux and so need a little pointer.

Basically I am conducting a project for my MSc based around Network Monitoring, currently I have a linux box which runs a number of monitoring apps, currently my setup looks like this:

ADSL router ->Hub--->switch ---->PC's / Wireless devices

with the network monitor "tapped" into the hub.
So basically all external traffic is repeated to the monitor interface.

However I wish to run the monitor at 100MBps since the amount of traffic being monitored is quite large for the current 10MBps Hub!!

So my question is how can i configure the linux box to accept traffic on one NIC and automatically forward all traffic to a second NIC? The end result I am looking for is like this:

ADSL router --> network monitor --> Switch ---> PC's / Wireless devices.

Thanks in advance

 

[Dj_Jestar]

Have you tried Smoothwall?

sounds like a simple enough router setup. I haven't used smoothwall personally, but I can't imagine it's difficult to use rules to tie outgoing/ingoing traffic to NIC's.

 

[BillytheImpaler]

DJ's got it just right. Smoothwall is made for this.

http://www.smoothwall.org/get/

 

[matja]

If your linux box is already setup with the right IP and subnet masks on the NIC's, just echo 1 > /proc/sys/net/ipv4/ip_forward or put it in a suitable script which gets executed at startup.

 

[markwombat]

If your linux box is already setup with the right IP and subnet masks on the NIC's, just echo 1 > /proc/sys/net/ipv4/ip_forward or put it in a suitable script which gets executed at startup.

Excellent, thanks a lot for this. I appreciate that Smoothwall does the forwarding aspect of what I desire but I am using a variety of network monitor tools already installed onto my Linux box and didnt really want to have to start afresh with different tools. But thanks anyway