A packet sniffer is a utility that has been used since the original release of Ethernet. Packet sniffing allows individuals to capture data as it is transmitted over a network. Packet sniffer programs are used by network professionals to diagnose network issues and by malicious users to capture unencrypted data like passwords and usernames in network traffic. Once this information is captured, the user can then gain access to the system or network.

If you want to keep information confidential or are concerned about packet sniffing, work on encrypted protocols and encrypt all sensitive data being sent over the Internet or network (e.g. e-mails). For example, e-mails can be encrypted using PGP and anyone still using Telnet should consider using SSH instead.

Related pages

Also see: Network terms, Port scanner, Promiscuous mode, Security terms, Wireshark