Folks,
Just a quick question. I know many of the new Fibre suppliers use CGNAT on their services. I also know this can cause issues with VOIP and SIP in particular, as, for example A&A have a VPN service designed to get round this issue.
So, is this an issue in practice?
Don't mobile networks also use CGNAT ? is this also an issue for mobile apps?
Dave
I don't see why fibre would imply a move to CGNAT.
I dont think fibre networks actally use CG NAT, its just dynamically allocated IPs.
Its the mobile phone networks that use CG NAT.
Some fibre providers do provide an option to have a Static IP, I have a FREE static IP address provided upon request, this is with Vodafone Gigafast that is on the City Fibre ALt-Net.
The issue with NAT is that it makes *incoming* opening of TCP/UDP connections harder.
Normally an outgoing app will have no issues.
Incoming listeners have to register, and maybe keep registering, their (translated) port/IP addresses with some centralised server.
That's no different, however, between local NAT and CGNAT...
There is simply no reason to dynamically allocate IP addresses to 'always on' services.
My fixed IP address is *de rigeur* with IDNET.
Indeed not, but it's not easy to get a fixed IP. Salespeople for many ISPs don't even know what that means, and BT a few years ago were charging £10 a month for a fixed address on a *business* account. And a 'fixed' IP address is simply a dynamic one with a reservation, which takes about two minutes to set up, as a one-off thing. I'm on Plusnet (oddly, part of BT) which was one of three ISPs I could find about five years ago offering fixed, and I couldn't afford A&A.
What you can't generally find out in advance is which ISPs have an interest in staying off email blacklists, and I know for a fact that BT doesn't. I've advised three former business clients to move away from BT, and they all suffered for not doing so.
Its not the Fibre but the suppliers. They were late on the scene in IP terms and so don't have enough routable IPV4 addresses to give one to every user.
It would be expensive and challenging to obtain more.
So for example by default both City Fibre and Giganet use CGNAT addresses. They will sell you a fixed routable IP for a monthly fee.
Dave
by default City Fibre uses CGNAT
Yes but some make a monthly charge for this....
Dave
SIP needs inbound connections. My router has SIP detection and opens and routes the ports as needed. I can't do that on the ISPs CGNAT
You probably could. SIP works *behind* router NAT.
I'm with Virgin. They don't offer static IP on domestic contracts, but I had read in advance that the dynamic IPs very rarely change - even after router reboots, power outages, etc. So far I've had the same IP address for the 3 years that I've been with them.
City Fibre is not an ISP. Whether or not you get a routeable IP address depends on which ISP you select to run over CF. CF is unusual amongst the altnets in this respect. Many of the others altnet fibre suppliers are also the sole ISP. That’s where you can run into trouble with CGNAT.
If thats the case why do A&A offer a VPN service specially to allow VOIP users to by-pass NAT?
Dave
That's interesting. I have suffered that with Heart Internet who were black-listed by Yahoo but you are the first person who has mentioned it in a post I have seen.
What happened to IPV6? It's been here for years but nobody seems to use it.
It's pretty horrible really.
Why don't you ask them? Perhaps there are other protocols in use than SIP
Generally the whole IP block gets on a blacklist, and unless the ISP is willing to discipline the actual offender and pay to get taken off the list, there's not a lot you can do. Another reason for using a 'professional' ISP rather than the cheaper mass-market ones is that their other customers are less likely to be hacked and turned into malware distributors.
But if you're on a blacklist, all you can do is use a smarthost, which your ISP or domain host may provide. I could probably do that now I'm retired, but previously I needed to see the actual transaction with the destination SMTP server when a client had an email problem. I moved from Demon, when Vodafone finally killed it, to Plusnet, and both seem to have been clean.
I can beat that. Mine has been unchanged for must be getting on for 20 years!
Am 16.07.2023 um 10:22:08 Uhr schrieb David Wade:
Use IPv6 for VoIP and you don't need to care. CGNAT makes incoming calls with VoIP mostly impossible.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.