Port 22 – SSH / SFTP Protocol Specification

Technical analysis, security advisories, vulnerability mitigation, and firewall syntax for TCP/UDP port 22 (SSH / SFTP).

Port Number 22

Transport Protocol TCP

Port Range Type Well-Known (0-1023)

Default Status Restricted / LAN

Service Description & Architectural Context

Secure Shell for encrypted remote administration and SFTP.

IANA / RFC Designation:

Port 22 is assigned to SSH / SFTP under the Internet Assigned Numbers Authority (IANA) service name registry. In enterprise infrastructure and homelab setups, services listening on this port must follow the principle of least privilege.

Security Analysis & Attack Surface Assessment

Disable root password login, enforce ED25519 public keys, and deploy Fail2ban.

Hardening Recommendations:

Do not expose port 22 to public WAN interfaces unless authenticated TLS or VPN wrapping is strictly enforced.
Enforce rate-limiting using Fail2ban, CrowdSec, or cloud edge DDoS protection.
Audit active listening sockets locally: ss -tulpn | grep :22 or netstat -ano | findstr :22.

Firewall Rule Snippets for Port 22

UFW (Ubuntu / Debian Linux)

sudo ufw allow 22/tcp

iptables (Standard Linux Kernel)

sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Windows PowerShell (Defender Advanced Firewall)

New-NetFirewallRule -DisplayName "Allow Port 22" -Direction Inbound -LocalPort 22 -Protocol TCP -Action Allow

Quick Port Jump

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