Get the Whitepaper called Post Exploitation using Metasploit pivot and port forward. A very nice feature in Metasploit is the ability to pivot through a meterpreter session to the network on the other side. This tutorial walks you through how this is done once you have a meterpreter session on a foreign box.
You can download it from the following link: https://packetstormsecurity.com/files/download/102580/Metasploit_pivot_n_portfwd.pdf
Source: https://packetstormsecurity.com/files/102580/Post-Exploitation-Using-Metasploit-Pivot-And-Port-Forward.html