Help understanding "shared address space"?

[hat]

My ISP recently upgraded me to fiber optic internet to the home, as they're moving everyone to straight fiber and moving off the old infrastructure. For whatever reason, sites like speedtest and whatismyip seem to correctly identify my public IP, while my router shows my public IP as 100.64.160.237. Unfortunately, this means if I set up my router to automatically update my DDNS, it winds up being this 100.64.160.237 which no one can connect to. I've learned this is apparently some sort of "shared address space" which is a concept I don't really understand, nor how it affects me as a server host. I run a Quake server and it would be a real shame if that became impossible. I would also very much like it if I could automatically update my DDNS without giving it a useless IP.

 

[nageme]

It's cgNAT. You don't have a dedicated external IP on the internet, and you can't use port forwarding.
The 100.64.* range is practically a LAN inside your ISP.

You'd either have to ask/pay the ISP for a real external IP, or use IPv6.

 

[R-T-B]

It's cgNAT. You don't have a dedicated external IP on the internet, and you can't use port forwarding.
The 100.64.* range is practically a LAN inside your ISP.

You'd either have to ask/pay the ISP for a real external IP, or use IPv6.

Yep. Welcome to the IPv4 shortage. It sucks.

 

[hat]

Okay, so I have a basic understanding of what's going on now. But I want to continue hosting my server... short of sorting something out with my ISP, what are my options?

 

[R-T-B]

Okay, so I have a basic understanding of what's going on now. But I want to continue hosting my server... short of sorting something out with my ISP, what are my options?

I guess you could pay for a VPN that offers full port forwarding.

 

[Wirko]

my router shows my public IP as

It's better not to post your IPs, either local or public, at public forums.

Also, as you mention a recent upgrade: you might have IPv6 usable now in parallel with v4. Has happened to me (and v6 also permanently teleported me to Australia, which I don't know where is.) Yeah, it's still incompatible with 3/4 of the world, but you may find a use for it, and it's probably unaffected by NAT.

 

[nageme]

incompatible with 3/4 of the world

Google's data says 40% adoption worldwide (and, e.g., 72% in France), but it's difficult to say how that translates to everyday users.

probably unaffected by NAT.

Well, almost by definition it isn't.

 

[hat]

I guess you could pay for a VPN that offers full port forwarding.

I've heard of this. I guess it's an option... but how would this work? After all, the VPN still has to reach me... how does it get through the cgnat?

It's better not to post your IPs, either local or public, at public forums.

Also, as you mention a recent upgrade: you might have IPv6 usable now in parallel with v4. Has happened to me (and v6 also permanently teleported me to Australia, which I don't know where is.) Yeah, it's still incompatible with 3/4 of the world, but you may find a use for it, and it's probably unaffected by NAT.

Seems like IPV6 still isn't available. I tried enabling it in my router and rebooting, and still wound up behind the IPV4 cgnat.

 

[Solaris17]

and still wound up behind the IPV4 cgnat.

You would. They will issue both you will actually have to look to see if you were issued a ipv6 address. If not then your isp doesn’t support it yet. You will get an ipv4 address either way.

 

[Wirko]

Seems like IPV6 still isn't available. I tried enabling it in my router and rebooting, and still wound up behind the IPV4 cgnat.

How did you check, did you try some IPv6 test website?
To clarify: IPv6, if it works at your location, won't change your situation regarding v4. Both protocols can work in parallel, not interfering with each other.

 

[Shihab]

how does it get through the cgnat?

The same way you're connecting to this site. You connect to a static IP (VPN provider/endpoint), which authenticates your NAT-assigned IP (using keys, passwords, etc), and communicates with it for the duration of the session.

That said, wouldn't it be easier to just rent a server instead of trying to host your own locally? I don't have any experience in the matter, tbh, but I think delegating the networking stuff would be much easier than hosting your own locally...

 

[nageme]

First things first, ask your ISP if there are options to get an real external IP (IPv4), and what's up with IPv6 support.

 

[eidairaman1]

This might help with understanding Network Address Translation, IPV4 and IPNG

THE UNTOLD STORY: How the PIX Firewall and NAT Saved the Internet

 

[dragontamer5788]

That said, wouldn't it be easier to just rent a server instead of trying to host your own locally? I don't have any experience in the matter, tbh, but I think delegating the networking stuff would be much easier than hosting your own locally...

Have you ever used a Quake server?

You just double-click the software then tell your friends your IP address. Alas, hat here doesn't have an IP address anymore, at least not a public IP address.

 

[hat]

Well, the issue was eliminated with a simple call to the ISP. They just removed the CGNAT just like that... all I had to do was reboot the modem and router.

That said, wouldn't it be easier to just rent a server instead of trying to host your own locally? I don't have any experience in the matter, tbh, but I think delegating the networking stuff would be much easier than hosting your own locally...

Well, no. Not only would that cost money unnecessarily when I already have a computer I literally use as a "server" (Plex, mostly), but it's really hard, if not impossible to find hosting for a Quake server in 2023. This is a video game from 1996, the processing and network resources required are basically zero today, and with this new fiber connection, there's no reason not to. Everything I need is here and doesn't cost me anything more to run a server than not to.

Have you ever used a Quake server?

You just double-click the software then tell your friends your IP address. Alas, hat here doesn't have an IP address anymore, at least not a public IP address.

It's a little more advanced today. I have a DNS everyone connects to, and there's a site with a server browser that somehow crawls active servers and reports statistics like who is on, that the server address is, what map is running etc.

 

[Shihab]

Well, no. Not only would that cost money unnecessarily when I already have a computer I literally use as a "server" (Plex, mostly), but it's really hard, if not impossible to find hosting for a Quake server in 2023. This is a video game from 1996, the processing and network resources required are basically zero today, and with this new fiber connection, there's no reason not to. Everything I need is here and doesn't cost me anything more to run a server than not to.

I meant it as an alternative to getting a VPN, which would also cost you money.
But since you are lucky enough to have an ISP that would give you a static IP for free, I suppose that's a moot point...

 

[Wirko]

But since you are lucky enough to have an ISP that would give you a static IP for free, I suppose that's a moot point...

Not hiding behing CGNAT doesn't necessarily mean it's static. @hat - if you're not sure, check with your ISP.

 

[hat]

I doubt it's a static IP, because it never was before. I'm just no longer behind CGNAT. Unless specifically giving me a static IP was their way of getting me out of CGNAT... either way, I'm fine with it.