Webmin is an open source control panel for web-hosting industry. Click here to see how install webmin on your server.

The default port numbers of webin control panels are:
1. Access Webmin Hosting Manager

   After installation, the port 10000 is the default port for Webmin control panel

2. Access Webmail,

   The port 20000 is the default port for accessing webmail in webmin

Configuring Your Firewall For Webmin
Some operating system block to access the webmin(10000) by default. In such case you need to add firewall rule to access webmin port(Open webmin port in firewall)
Step 1:
Login to server via SSH as root
Step 2:
Add the following rule in your server firewall to open webmin port(10000)

iptables -A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT
/etc/init.d/iptables restart
Note: Run this command to view rule is added or not 'iptables -L -nv --line-number'

That’s it. I hope this helps you to access and add rule for your webmin server.