Port 20: FTP-DATA
Port 20 carries the data channel for classic FTP. The control channel on port 21 negotiates transfers, then file bytes flow over port 20 in active mode.
TCPFile transferUnencrypted by defaultIANA assigned
| Port number | 20 |
|---|---|
| Service | File Transfer Protocol (data) |
| Protocol | TCP |
| Category | File transfer |
| Default encryption | No |
Security note. Port 20 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 20 used for?
Port 20 carries the data channel for classic FTP. The control channel on port 21 negotiates transfers, then file bytes flow over port 20 in active mode.
Is port 20 TCP or UDP?
Port 20 (FTP-DATA) uses TCP.
Is port 20 secure?
Port 20 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 20 on my firewall?
Only if you specifically need FTP-DATA. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.