You should encrypt everything. These are what you need: BackTrack 4,0, modify IP tables, Python and ARPspoofing. Program the PC to flip to forwarding mode. Adjust the programming in the IP tables. You are convincing the host and the client that the man (PC) in the middle is the host and capture passwords, user names and other information from unsuspecting clients. This program strips the "S" from "https" which make your computer vulnerable to hackers. You need to observe the address bar and make sure that it says "https" rather than "http". Use SSH, SSL or VPN tunnel to be safe.