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CCIE Security v3.0 Quick Reference: Application Protocols

Chapter Description

This sample from CCIE Security v3.0 Quick Reference includes definitions and explanations of HTTP, HTTPS, SMTP, FTP, and DNS.

File Transfer Protocol

FTP allows users to transfer files from one host to another. FTP is a TCP-based connection-oriented protocol, and it uses port 21 to open the connection and port 20 to transfer data. FTP uses clear-text authentication. FTP clients can be configured for two modes of operation: PORT (active) mode and PASV (passive) mode. Figure 3-1 shows FTP modes of operation between an FTP client and FTP server for both the active and passive mode.

Figure 3-1

Figure 3-1 Overview of FTP Operation and Operating Modes

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