Solved DNS not reachable - MODULUS trunk

[mikeB200]

Hello

i have an issue from a reinstallation i made yesterday. Transfer my installation from windows 10 to debian
i cant register one of my trunks anymore

please see below:


Registration at modulus SIP Trunk has failed. Destination (sip:185.73.43.250:6050;lr) is not reachable, DNS error resolving FQDN, or service is not available.
SIP Server ID: 12293 09/22/2020 9:32:54 AM


modulus provided the ports (instead of 5060 they say 6050 is ok) anyway i tried both ports but nothing.

please advice.

thanks

 

[AWS2P]

You didn't say if PBX are on premise or Cloud?
Is your public IP stay the same when you did your transfer?

 

[JohnS_3CX]

Hi Mike,

Did you run your firewall checker and fully pass on the new install? If yes, then look below:

Firstly, I would recommend to delete the trunk and recreate it using our default template for Modulus

Then open a 2nd tab a start a capture on your PBX (via Activity Log page)

From the first tab go and restart your SIP service.

Allow some time for the service to restart and attempt to register and then end the capture.

Once you have the capture you should open it in Wireshark and see what happens with your DNS resolution by filtering for something like dns and frame contains "modulus"

After this, you can also filter for sip and ip.addr==185.73.43.250 to see what happens when the PBX tries to register.

 

[mikeB200]

Hi Mike,

Did you run your firewall checker and fully pass on the new install? If yes, then look below:

Firstly, I would recommend to delete the trunk and recreate it using our default template for Modulus

Then open a 2nd tab a start a capture on your PBX (via Activity Log page)

From the first tab go and restart your SIP service.

Allow some time for the service to restart and attempt to register and then end the capture.

Once you have the capture you should open it in Wireshark and see what happens with your DNS resolution by filtering for something like dns and frame contains "modulus"

After this, you can also filter for sip and ip.addr==185.73.43.250 to see what happens when the PBX tries to register.

thank you John.

It seems that for now the issue has been resolved.

Modulus IP tree was in IP blacklisted menu in the form of: DENY to 185.0.0.0 all communication, thus the 3CX could not go through.

However, even with the DENY listed IP address, under windows 10 on-premise installation we had tillyesterday, modulus was able to connect just fine! how i dont know.

I assume something else might be there in the settings and could be the FQDN or public address of my system.

also to answer a question about the firewall. I have not opened outside ports to the 3cx system as I am afraid of hacking. Thus my firewall test never completes successfully.


thank you for the input.

 

[JohnS_3CX]

Hi Mike,

Glad to hear it was resolved, and yes if it was blacklisted it makes sense now.