From the course: Wireshark Essential Training
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Following an FTP transaction - Wireshark Tutorial
From the course: Wireshark Essential Training
Following an FTP transaction
- [Instructor] File transfer protocol resides at the application layer of the OSI model. FTP transfers files using TCP ports 20 and 21. Port 21 is the command channel on the FTP server and port 20 is the secondary port used to transfer data. Once you get into the server, you're going to see a series of reply codes and this will tell us the state of the data transfer. Classic FTP uses what's called an active request, meaning the client initiates that data transfer and the FTP server maintains state information such as current directory and any user authentication. However, most likely you're going to see a passive request. And this is preferred for clients that are behind a firewall as it's more secure, because the client, not the server, initiates the transfer. Basically the client says to the server, you sit back, I'll do the driving. It first asks the server to accept a data connection over a new TCP port and the server…
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