Tools / Port checker / 6443
Is port 6443 open?
Port 6443 is Kubernetes API. Enter your server below to test it from Dallas, Amsterdam and London.
What port 6443 is used for
The Kubernetes API server, used by kubectl and cluster components.
Should port 6443 be open?
Open it only to the addresses that need it. Restrict to administrator addresses and keep anonymous authentication disabled.
How to open port 6443
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 6443 proto tcp
Rocky, Alma or CentOS with firewalld:
sudo firewall-cmd --permanent --add-port=6443/tcp && sudo firewall-cmd --reload
Windows Server, in PowerShell as administrator:
New-NetFirewallRule -DisplayName "Port 6443" -Direction Inbound -Protocol TCP -LocalPort 6443 -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.