Dictionary of Information Security

P

packet in data communication, a sequence of binary digits,

including data and control signals, that is transmitted

and switched as a composite whole.The data, con-

trol signals, and possibly error control information

are arranged in a specific format, according to the

communications protocol. In the TCP/IP world,

packets have specific names under different protocols

and different layers. At the application layer,TCP

(Transmission Control Protocol) has streams and

UDP (User Datagram Protocol) messages. At the

transport layer,TCP has segments and UDP packets.

At the Internet (network) layer are datagrams, and at

the network access (data link) layer are frames.

packet filter one of the simplest and earliest forms of a

firewall, a packet filter accepts or ...