To allow incoming connections on port 5991 in Ubuntu, you can use the ufw (Uncomplicated Firewall) utility, which is the default firewall configuration tool in Ubuntu. Below are the detailed steps to open port 5991:

Step-by-Step Guide

Step 1: Check the Status of UFW

1. Open Terminal:
   • You can open the terminal by pressing Ctrl + Alt + T.
2. Check UFW Status: sudo ufw status
3. This command shows the current status of UFW and configured rules. If UFW is inactive, you will need to enable it.

Step 2: Enable UFW (If Not Already Enabled)

1. Enable UFW: sudo ufw enable
2. You will be prompted to confirm the enabling of the firewall.

Step 3: Allow Incoming Connections on Port 5991

1. Allow TCP Connections on Port 5991: sudo ufw allow 5991/tcp
2. This command allows incoming connections on port 5991 using the TCP protocol.If your application uses UDP, you can allow UDP connections as well: sudo ufw allow 5991/udp
3. Reload UFW to Apply Changes: sudo ufw reload This command ensures that UFW reloads the rules and applies any changes made.