This is a whitepaper that discusses pivoting attacks with Metasploit. Pivoting is a technique using a compromised system to attack other systems on the same network. Consider a scenario where there is some juicy information hosted inside a local network and there is only one system which is connected to internet. In this scenario, an attacker can compromise the system which is connected to internet and then use that particular compromised system in-order to test or attack other systems in the same network which are only accessible via local network.
You can download it from the following link: https://packetstormsecurity.com/files/download/146024/Pivoting.pdf
Source: https://packetstormsecurity.com/files/146024/Pivoting-Metasploit.html