How to fix the problem described in my frustrations page

Requirements: Knowledge of Linux and a Linux computer

Note: Make sure you are NOT running sendmail or any other SMTP server on your computer, otherwise you will be doing exactly what this is trying to avoid.

This is a process with three essential parts. I will deal with each separately.

1. ARP Spoofing

Firstly, you need to take the place of the mail server. This can be done by adding fraudulent entries to the router's ARP cache. This can be done using arp-sk from www.arp-sk.org. I won't post details of the exact command line, however.

2. Transparent Proxying - Redirecting to the local machine

Next, you need to capture the packets that should be going to the mail server as, although the router now believes you to be the mail server, your computer doesn't believe it is.

To do this, use ipchains. The following command line will redirect the traffic to you:

ipchains -A input -p tcp --dport 25 -j REDIRECT

3. Sending the data to the correct place

This is a relatively simple part. I used aproxy from www.dilledabb.de/projects/aproxy.html (WARNING: Site is in German). This can then be configured to redirect from the SMTP port on your computer to the correct port on the correct machine.