I need to host a Server on Public IP in france. I heard from some where that some ISPs will act as NAT and will block all inbound connections. Do anyone have any information on such service providers?

  • 7
    Yes, some consumer ISPs use carrier-grade NAT. For more information, you will need to ask them directly. If you're hosting a server in a datacenter, you'll need a "real" ISP, and these certainly will not be using NAT.
    – EEAA
    May 5, 2014 at 13:00
  • Why don't you ask your ISP?
    – joeqwerty
    May 5, 2014 at 13:44

3 Answers 3


Yes, there are plenty of those providers, however, I have yet to see one which sells Business-grade services. (Datacenter hosting, ISP with Business customers). It's mostly used in consumer deployments. Reasons are described in other answers here.


Yes, some ISPs do NAT. And they are often not communicating this fact clearly enough for all customers to realize this before signing up for the service.

This practice is known as Carrier Grade NAT. You may see it mentioned with one of these other terms: CGN, Large Scale NAT, LSN, NAT444.

There is only one long term solution for this, which is IPv6. Deployment of IPv6 is lagging behind, but France is not lagging as far behind as the rest of the world, so you definitely should ensure your server gets an IPv6 address.

The optimal would be to get both IPv4 and IPv6 address on the server, but if you for some reason can only get one of the two, there are services, which can help you get access to the other protocol as well.


The pool of unallocated IPv4 addresses has been empty since September 2012, so ISPs will be running low on IPv4 addresses as they can't get any new ones. Expect to see ISP NAT, DS-Lite and MAP more and more.

Having your own IPv4 address is not feasible anymore these days. I wouldn't be surprised to see data centres with IPv6-only inside, and a shared IPv4-to-IPv6 translator in or near a load balancer.

Unfortunately IPv6 deployment (which is designed to solve this) is far far behind. Keep pushing your suppliers for IPv6 so that we can run 'real' networks again, instead of this NAT mess!

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    While not answering the question directly, it is still useful :)
    – MichelZ
    May 5, 2014 at 13:45
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    Sander, you keep saying this, and it keeps not being true. RIPE, for example, simply isn't out of unallocated addresses yet. This graph shows that they had slightly less than 14 million unallocated v4 addresses as of 28/4/14 - for Europe. What they have been on since Sep 2012 is their last /8, which triggers more draconian allocation policies (PA-space to LIRs only in /22s, no PI-space). ICANN has no more /8s to give out, it is true, but "the pool of unallocated v4 addresses" simply isn't empty yet.
    – MadHatter
    May 5, 2014 at 14:22
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    @MadHatter: I know that policy very well (I'm the co-chair of the RIPE address-policy working group, so I should know). There is indeed a pool of /22s where every LIR can get one /22. That is done so that everyone (and especially newcomers) in the internet business can have some IPv4 addresses so they have some chance of survival, but it is not something you can run an ISP or hosting business on without having to jump through NAT hoops. But as an LIR, once you get your single /22, there are no more IPv4 addresses to be had. So for practical purposes RIPE has run out. May 5, 2014 at 14:55
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    Sander, I'm sorry, I had no idea. Yes, of course you would know the current allocation state very well, and I apologise for checking you on it. I also agree that exhaustion is close, and you will know from elsewhere on SF that I'm a big fan of ipv6 and work to put it in everywhere I can. Nevertheless, I don't think anyone's life is improved by inaccuracy and scaremongering, so I hope you will forgive me for making my point. Your statement above, which seems to boil down to our being in the last days of ipv4 availability, is cogent, precise, and should be widely read.
    – MadHatter
    May 5, 2014 at 15:04
  • @MadHatter No apologies necessary! I do try to simplify the message to avoid confusing newbies. RIPE would have run out in October 2012 if the last /8 hadn't been saved so new ISPs still have a chance to compete with the existing ones. Some people preferred a complete runout, but imagine an internet where every new ISP or data centre has to buy/rent/beg an existing ISP for some IPv4 addresses? When RIPE policy proposal 2010-02 (Allocations from the last /8) was introduced, one thought was about Neelie Kroes blaming us for abuse of monopoly and encouraging anticompetitive behaviour ;) Cheers! May 5, 2014 at 18:51

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