Firewall check failing on detecting SIP ALG

[luminite]

Hi all

Can I ask if anyone's 3CX is failing the SIP ALG firewall check?

I think I'm getting a false positive result which 3CX are saying could be the cause of my problems, but I'm not convinced that there is not a problem their end with this test. They seem to have had a problem this this test their end in the past as per, as per: https://www.3cx.com/community/threads/3cx-sip-alg.52959/

Thanks in advance

 

[eddv123]

If yours like the post is a SonicWall I always find customers struggle with the 3CX Firewall Checker:
https://www.3cx.com/docs/firewall-checker/

I had a customer the other day solve this by in the Sonicwall WAN interface, enabling "Do not send ICMP Fragmentation Needed for outbound packets over the Interface MTU".

I cannot see the technical reasoning why this would have solved the issue but they say it did.

 

[YiannisH_3CX]

Hello @luminite

You can confirm if you are getting a false positive from the firewall checker by using wireshark and the below guide. https://www.3cx.com/docs/firewall-checker/
You can see the traffic going in and out to the PBX using wireshark and confirm the results provided by the firewall checker.