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Comment by BrianGraggg | Hacker News Reader

You can request to go into bridge mode which will bypass the internal residential gateway (NAT).

If an ISP is NAT'ing everyone (which I've heard of referred to as an "InterNAT Service Provider"), does "bridge mode" mean you get a real public IP? How does that work with everyone else still behind the NAT?

(I have an actual end-to-end-connectable public IP from my ISP, which from the general discussion seems like an increasingly rare thing --- they keep pestering me to "upgrade" to outrageously faster yet slightly cheaper plans with a "free router included", so I suspect they are trying to get me to give up that IP...)

There are 2 different topics here. One is carrier grade NAT (CGNAT), which is used by ISPs that have run out of IPv4 addresses so you don’t get a real public IPv4 address, although you should have a public IPv6. If you’re unlucky enough to be on one of thee ISPs there’s likely not much you can do.

The other issue is ISP provided gateways that handle authentication onto the ISP network, like ATT fiber. These devices contain the certificate/keys to gain access to the network. Unfortunately theses devices also try to be more than just an auth device/gateway. In ATT’s case the gateway also handles some Uverse/IP TV services so they don’t have a true bridge mode where they send all traffic to another device. This approach then causes issues like update downtime or NAT table issues.

Either of these issues shouldn’t be caused simply by an ISP provided router. If an ISP wants to implement either approach they will do so without your approval.

> One is carrier grade NAT (CGNAT), which is used by ISPs that have run out of IPv4 addresses so you don’t get a real public IPv4 address, although you should have a public IPv6. If you’re unlucky enough to be on one of thee ISPs there’s likely not much you can do.

This is true. Your options look like:

1. Get a new ISP

2. Get a VPN that supplies you with a public IP (these exist)

3. Hope you can do whatever you need on IPv6 instead

Some CGNAT ISPs will also sell service with a public IPv4 for a premium. That's probably the most "user-friendly" option but it's also probably something they don't advertise and you need to ask for explicitly, if offered.

you can still get around this with some effort [1] and a pfsense box, the pfsense box gets wan from the ont and the original att router is hung off a third nic where it's allowed to do 802.1x and nothing else. the setup was a little challenging at first but has been maintenance free since. maybe there is a technical reason they have their network set up this way but i was offended at the idea of being prevented from using my own router.

[1] https://github.com/MonkWho/pfatt

> carrier grade NAT (CGNAT), which is used by ISPs that have run out of IPv4 addresses … If you’re unlucky enough to be on one of thee ISPs there’s likely not much you can do.

I had the same SSH dropout problem, asked my ISP[1] to switch me from CGNAT to dedicated IPv4; they did, and it's fixed.

[1] Aussie Broadband, a smaller ISP in Australia renowned for good customer service.

Consider sending Aussie Broadband a link to my blog post. It should be a simple fix for them to raise the timeout, which should fix the problem for all their customers.

The AT&T gateways do not have a true bridge mode. They still use NAT even if they look like they are just passing the connection on.

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