Port lookup
Port 20 — TCP
FTP data
FTP (File Transfer Protocol) moves files between computers. Port 20 carries the file data, while port 21 carries the commands.
Why it matters
If you see traffic on this port, a file transfer is in progress, so check which files are moving.
Back to the port listLearn on the job
Ports are daily work on the network desk.
Look up a port here, then see it in real work on the network desk.