Port 5900 · VNC

Port 5900 is VNC, TCP.

Virtual Network Computing — cross-platform GUI remote access. Older implementations often have weak authentication.

Palo Alto

Create the service object for this port, then allow the App-ID on it. Restricting the rule to the port's service object keeps the rule working on a non-default port and stops the App-ID matching on other ports. Replace the placeholders with your own rule name and zones.

set service tcp-5900 protocol tcp port 5900

set rulebase security rules <rule-name> from <from-zone> to <to-zone> source any destination any application vnc-base service tcp-5900 action allow

Risk and exposure

Rated high risk. Services on this port are commonly targeted by attackers. Keep it off the internet, or put it behind a VPN or a strict source allow-list, and monitor access.

Check it

• Linux ss -tlnp | grep :5900
• PowerShell Test-NetConnection <host> -Port 5900
• nmap nmap -p 5900 <host>

Related ports

• 3389 RDP
• 22 SSH
• 23 Telnet
• 5985 WinRM HTTP
• 5986 WinRM HTTPS

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