Is port 20 (FTP Data) dangerous?

Port 20 is classified as critical risk and should not be exposed to the public internet. It transmits data without encryption, making it vulnerable to eavesdropping and credential theft.

Should port 20 be open on my firewall?

No, port 20 should not be open to the public internet. Block it at the firewall and use encrypted alternatives such as SSH, SFTP, or HTTPS instead.

What transport protocol does port 20 use?

Port 20 (FTP Data) uses the TCP transport protocol and falls under the File Transfer category.

:20 (TCP)

FTP Data

Critical Risk

TCP — File Transfer

Port Overview

Port Number 20

Service Name FTP Data

Transport Protocol TCP

Category File Transfer

Security Risk Critical

Port Range Well-Known (0-1023)

What is Port 20?

FTP data transfer channel. Used in active mode FTP for the server to establish a data connection back to the client. Credentials and files are sent in plaintext.

TCP File Transfer Commonly Used

Security Considerations

Port 20 (FTP Data) is classified as critical risk. This port should not be exposed to the public internet. The service transmits data without encryption, making it vulnerable to eavesdropping, credential theft, and man-in-the-middle attacks.

Recommendation: Block this port at the firewall. Use encrypted alternatives (SSH, SFTP, HTTPS) instead.