File Transfer Protocol

ftp.pcap

The File Transfer Protocol (FTP, RFC 959) is a Layer 7 protocol that is used to transfer data between a server and client. Operating on ports 20 and 21, FTP is one of the most commonly used file transfer utilities. Because FTP is a client/server protocol, all communication in the capture file involves back-and-forth traffic between a client computer and a server computer. As with all TCP processes, FTP begins with a standard TCP handshake, as shown with packet 1 and in Figure 6-13 below.

The TCP handshake is prevalent in various communication types.

Figure 6-13. The TCP handshake is prevalent in various communication types.

Once the handshake process completes, the server sends ...

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