Level 1: Cadet


We're having trouble allowing access to our internal VOIP and VPN servers for mobile devices (or laptops tethered to said devices) because the firewall on our network is blocking 'private' source traffic per RFC 1918, which includes the range that is issued to devices behind the CGNAT system.


Rather than allow the whole 16 million addresses through the firewall, is there a smaller IP block that I can allow through that allows only Telstra CGNAT devices through?



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Support Team
Support Team

Re: CGNAT IP Block

Hey sccf, welcome to Crowd Support.


Unfortunately that is not one I know how to answer, but the rest of the community will hopefully come through with the goods.


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Level 25: The Singularity
Level 25: The Singularity

Re: CGNAT IP Block

The thing is, Telstra devices can be assigned any of that range. Being a Private address range sitting behind a CGNAT, it also means that any device from any other carrier can be assigned an address in that range.

My work uses different portions of that addressing block for its internal network.

It's the public IP address that makes the difference, as that is where the traffic funnels through.
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