NGN Password Sinffer doesn't need to be installed.

The most powerful and effetive password sniffer. NGN Password Sniffer can listen on your LAN and enable network administrators or parents to capture passwords of any network user. Currently NGN Password Sniffer can monitor and capture passwords through FTP, POP3, HTTP, SMTPand etc. 
Ace Password Sniffer works passively and don't generate any network traffic,and it have no any GUI. therefore,it is very hard to be detected by others.

This stealth-monitoring utility is useful to recover your network passwords, to receive network passwords of children for parents, and to monitor passwords abuse for server administrators. 

Click PwdSniffer.exe to start the NGN Password Sinffer. Then click begin monitor button.
Then the monitor will start when the system starting.

All passwords will be saved in c:passwords.txt.