ISC2 CISSP Certified Information Systems Security Professional Official Study Guide

by Mike Chapple

International Assigned Numbers Authority (IANA, www.iana.org)

Port Numbers The IANA recommends that ports 49152 to 65535 be used as dynamic and/or private ports. However, not all OSs abide by this.

Transmission Control Protocol (TCP) operates at layer 4 (the Transport layer) of the OSI model.

full-duplex

The three-way handshake process (Figure 11.7) is as follows: The client sends a SYN (synchronize) flagged packet to the server. The server responds with a SYN/ACK (synchronize and acknowledge) flagged packet back to the client. The client responds with an ACK (acknowledge) flagged packet back to the server.

two methods to disconnect the TCP

session. First, and most common, is the use of FIN (finish) flagged packets instead of SYN flagged packets.

Second is the use of an RST (reset) flagged packet, which causes an immediate and abrupt session termination. (Please see the discussion of the TCP header flag later in this section.)