Port 21 — FTP
Quick reference for TCP/UDP port 21, used by FTP. Includes what the service does, security guidance and related ports.
What is port 21?
File Transfer Protocol control channel.
What port does FTP use?
FTP listens on port 21 by default.
Security guidance
High risk — do not expose to the internet
Port 21 (FTP) is high-risk because the service it carries is a frequent target for credential attacks, brute force or unpatched-vulnerability scanning. Keep it bound to localhost or your VPN, never forward it directly on a router, and require strong authentication.
Related ports
Frequently asked
What is port 21 used for?+
Port 21 is the standard TCP/UDP port for FTP. File Transfer Protocol control channel.
What port does FTP use?+
FTP listens on port 21 by default.
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