FTP Sequence Diagrams

Here we explore the sequence of interactions in a typical FTP (File Transfer Protocol) session. Individual sequence diagrams for interactions on Port 20 and 21 are also included.

The complete sequence diagram can be divided into the following steps:

  • DNS Query to obtain the IP address for the FTP Server
  • FTP Telnet connection setup and login. (USER and PASS commands)
  • Obtaining a directory listing (PORT and LIST command)
  • Changing directory (CWD command)
  • Downloading a file using FTP get (PORT and RETR command)