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 风险

TCP — File Transfer

端口概览

端口号 20

服务名称 FTP Data

传输协议 TCP

类别 File Transfer

安全风险 Critical

端口范围知名端口 (0-1023)

什么是端口 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 常用

安全注意事项

端口20（FTP Data）被归类为严重风险。此端口不应暴露在公网上。该服务在未加密的情况下传输数据，容易受到窃听、凭据窃取和中间人攻击。

建议：在防火墙处封锁此端口。改用加密替代方案（SSH、SFTP、HTTPS）。

FTP Data

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端口概览

什么是端口 20?

安全注意事项

相关协议

相关端口 — File Transfer

相关术语