Ports which should be opened

For server some ports should be opened:

• TCP 80 - for GUI/HTTP
• TCP 22 - for SSH connection
• UDP 4569 - for IAX2 connection
• UDP 5060, 10000-20000 - for SIP connection

You can test which TCP ports are opened using nmap tool:

nmap -vv -P0 23.45.67.89

https://www.virtualizationhero.com/docs/manuals/linux/RHL-9-Manual/security-guide/s1-server-ports.html