The firewall blocks the radio's data

This is common on a new installation of Linux Mint, and on other distributions that use the ufw firewall.

Symptoms

• The radio does not appear in the connection dialog.
• Direct IP connects, but the panadapter, waterfall, audio and meters stay empty.
• SmartLink fails.

Cause

The radio sends its discovery announcements, spectrum, waterfall, audio and meter data to the computer as UDP packets. The firewall blocks incoming UDP packets. The command connection uses TCP, so Direct IP still connects, but no data arrives.

Let the radio's traffic through

1. Open a terminal. On Linux Mint, select Menu › Terminal.

2. Show the firewall status:

   sudo ufw status
   

3. Type your login password when the terminal asks for it.

   The terminal does not show the characters as you type them. This is normal.

4. Read the first line of the output.

   • Status: inactive - The firewall is not the cause. Stop this procedure. See Troubleshooting connecting for other causes.
   • Status: active - Continue with step 5.

5. Allow incoming UDP traffic on ports 4991 to 4994:

   sudo ufw allow 4991:4994/udp
   

6. Close RimuSDR.

7. Start RimuSDR and connect to the radio.

The radio now appears in the connection dialog. The panadapter, waterfall, audio and meters show data, and SmartLink connects. You do this one time only. The rule stays after you restart the computer.

If the problem continues

Contact support. Include the output of this command:

sudo ufw status verbose

Other firewalls

Some distributions use a different firewall, for example firewalld on Fedora. Open the same UDP ports 4991 to 4994 with the tools for that firewall.