Sniffers are software applications that can be used to intercept confidential data on the Internet. These applications can be used in unauthorized ways, but they are also used by administrators for troubleshooting, traffic administration, and intrusion detection.
A sniffer that specializes in sniffing out data packets is called a packet sniffer. Such a packet sniffer has a special programming interface with which data packets can be intercepted: Packet Capture (pcap). The captured data is analyzed and further processed. In another approach, all data packets that are sent via a specific collision domain are spied out. This is software that uses the network card and spies out data packets from application protocols that are transmitted unencrypted, such as the Telnet protocol, the FTP protocol, the Simple Mail Transfer Protocol( SMTP) and some more.
Sniffers can be warded off through various measures, such as two-factor authentication using a combined One Time Password( OTP) composed of two factors: the Personal Identification Number ( PIN) and a randomly assigned password. Other methods of preventing sniffers include a hierarchical switching architecture and encryption of the transmission channel, for example using IPsec.