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A most elegant TCP hole punching algorithm
21–30 of 111 posts
Re: A most elegant TCP hole punching algorithm
#22Needing to punch holes in NAT is one of the most idiotic own-goals in the entire field of networking. NAT is effectively your router doing DHCP with a 17-bit suffix (16-bit port + 1 bit for UDP vs TCP) to each of your applications and then not telling you the address it gave you or how long it is good for (which is what a regular DHCP lease does). This is in addition to it, most likely, already doing regular DHCP and…
> If you could just ask your router for a lease on a chunk of IP+NAT addresses The “just” is doing a lot of lifting there. I’m glad the various port mapping protocols didn’t really take off and it looks like IPv6 is going to actually make it instead. Much less complexity in most parts of the stack and network.
It is always a mystery how people just randomly misinterpret what I write. At literally no point did I mention port mapping.
I am pointing out how the problem NAT “solves” is just dynamic address configuration. They have implemented a N+K bit address where the N-bit prefix is routed and allocated using IP and the low K-bits are routed and allocated like a custom fever dream.
You can just do it all the same way instead of doing it differently and worse for the low bits.
To be clear, the router should rewrite zero bits in the packet under the scheme I am describing just like how routers have no need to rewrite any bits when routing to a specific globally-routable IP address.
You get a lease for a /N+K address. /N routes to your router which routes the last K bits just like normal as if it had a /N-M to a /N route. This is a generic description of homogenous hierarchical routing.
Re: A most elegant TCP hole punching algorithm
#23[flagged]
This is an AI slop bot
Re: A most elegant TCP hole punching algorithm
#24Earlier quoted context omitted.
No, hence the all caps ai disclaimer. But seems plausible
Lord, we're how many years into using LLMs, and people still don't understand that their whole shtick is to produce the most plausible output - not the most correct output? The most plausible output might be correct, or it might be utter bullshit hallucinations that only sound correct; the only way to tell is to actually try it or cross-reference primary sources. Unless you do, the AI answer is worthless. The reason…
Exactly! This is what LLMs do: they bullshit you by coming across as extremely knowledgeable, but as soon as you understand 5% of the topic you realise you've been blatantly lied to.
Re: A most elegant TCP hole punching algorithm
#25Needing to punch holes in NAT is one of the most idiotic own-goals in the entire field of networking. NAT is effectively your router doing DHCP with a 17-bit suffix (16-bit port + 1 bit for UDP vs TCP) to each of your applications and then not telling you the address it gave you or how long it is good for (which is what a regular DHCP lease does). This is in addition to it, most likely, already doing regular DHCP and…
> If you could just ask your router for a lease on a chunk of IP+NAT addresses The “just” is doing a lot of lifting there. I’m glad the various port mapping protocols didn’t really take off and it looks like IPv6 is going to actually make it instead. Much less complexity in most parts of the stack and network.
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Re: A most elegant TCP hole punching algorithm
#26Earlier quoted context omitted.
> If you could just ask your router for a lease on a chunk of IP+NAT addresses The “just” is doing a lot of lifting there. I’m glad the various port mapping protocols didn’t really take off and it looks like IPv6 is going to actually make it instead. Much less complexity in most parts of the stack and network.
It is always a mystery how people just randomly misinterpret what I write. At literally no point did I mention port mapping. I am pointing out how the problem NAT “solves” is just dynamic address configuration. They have implemented a N+K bit address where the N-bit prefix is routed and allocated using IP and the low K-bits are routed and allocated like a custom fever dream. You can just do it all the same way instea…
NAT allocates ports. If you reserve a port, that's old good port forwarding.
Re: A most elegant TCP hole punching algorithm
#27> Many home routers try to preserve the source port in external mappings. This is a property called “equal delta mapping” – it won’t work on all routers but for our algorithm we’re sacrificing coverage for simplicity. It is precisely this point that has flummoxed me when connecting my p2p wireguard config[1] with a friend that uses a pfsense router, no matter what we tried, pfsense always chooses a random source port…
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We can all run this through our LLM if choice, why post this?
Re: A most elegant TCP hole punching algorithm
#28Earlier quoted context omitted.
> If you could just ask your router for a lease on a chunk of IP+NAT addresses The “just” is doing a lot of lifting there. I’m glad the various port mapping protocols didn’t really take off and it looks like IPv6 is going to actually make it instead. Much less complexity in most parts of the stack and network.
It is always a mystery how people just randomly misinterpret what I write. At literally no point did I mention port mapping. I am pointing out how the problem NAT “solves” is just dynamic address configuration. They have implemented a N+K bit address where the N-bit prefix is routed and allocated using IP and the low K-bits are routed and allocated like a custom fever dream. You can just do it all the same way instea…
If I understand it correctly, you're suggesting formalizing a way to make parts of the (host-specific) port canonically part of the network-wide address, no?
This still sounds like a very bad mixing of layers, even if done in a perfectly standardized and uniform way.
> It is always a mystery how people just randomly misinterpret what I write.
If this is intended literally and not as a general complaint: My main problem of understanding your suggestion is that I don't know what you mean by "IP+NAT address". NAT is a translation scheme, not an address.
Maybe it would be clearer if you could provide an example?
Re: A most elegant TCP hole punching algorithm
#29Earlier quoted context omitted.
Did you validate this solution yourself?
No, hence the all caps ai disclaimer. But seems plausible
But then why make this comment at all, even despite the disclaimer? Anyone can prompt an LLM. What's your contribution to the conversation?
To be clear, I use LLMs to gut check ideas all the time, but the absolute minimum required to share their output, in my view, is verification (can you vouch for the generated answer based on your experience or understanding), curation (does this output add anything interesting to the conversation people couldn't have trivially prompted themselves and are missing in their comments), and adding a disclaimer if you're at all unsure about either (thanks for doing that).
But you can't skip any of these, or you're just spreading slop.
Re: A most elegant TCP hole punching algorithm
#30Earlier quoted context omitted.
Lord, we're how many years into using LLMs, and people still don't understand that their whole shtick is to produce the most plausible output - not the most correct output? The most plausible output might be correct, or it might be utter bullshit hallucinations that only sound correct; the only way to tell is to actually try it or cross-reference primary sources. Unless you do, the AI answer is worthless. The reason…
Exactly! This is what LLMs do: they bullshit you by coming across as extremely knowledgeable, but as soon as you understand 5% of the topic you realise you've been blatantly lied to.
Even if you get 70% blatant lies and 30% helpful ideas, if you can cheaply distinguish the two due to domain expertise, is that not still an extremely useful tool?
But to the point of this thread: If you can't validate their output at all, why would you choose to share it? This was even recently added to this site's guidelines, I believe.