Tools / Port checker / 5900
Is port 5900 open?
Port 5900 is VNC. Enter your server below to test it from Dallas, Amsterdam and London.
What port 5900 is used for
Virtual Network Computing: remote control of a graphical desktop.
Should port 5900 be open?
Should not face the internet directly. Many VNC servers have weak or no authentication. Tunnel it through SSH or a VPN instead of exposing it.
How to open port 5900
Ubuntu or Debian with ufw, allowing only your own address (replace 203.0.113.10):
sudo ufw allow from 203.0.113.10 to any port 5900 proto tcp
Rocky, Alma or CentOS with firewalld:
sudo firewall-cmd --permanent --add-port=5900/tcp && sudo firewall-cmd --reload
Windows Server, in PowerShell as administrator:
New-NetFirewallRule -DisplayName "Port 5900" -Direction Inbound -Protocol TCP -LocalPort 5900 -Action Allow
Then check that the service listens on all addresses, not only 127.0.0.1, and test again above.
Check another port
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Run your service on a PrivateByte server: a firewall you control and every port yours to open.