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CGNAT version 2 (sh.itjust.works)
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[-] vivendi@programming.dev 139 points 6 days ago

Every day I regret becoming a network engineer more and more

You have a clusterfuck of a clusterfuck because corpocunts make more money from keeping everyone on shit old stacks

The network engineer to communist/anarchist pipeline is real

[-] pineapplelover@lemmy.dbzer0.com 28 points 6 days ago

My goal is to be a network engineer...hmmmm

[-] Bane_Killgrind@lemmy.dbzer0.com 21 points 6 days ago

Sounds like your goal is to be an anarchist, welcome.

[-] NigelFrobisher@aussie.zone 56 points 6 days ago

Every day we move further away from God.

[-] jenny_ball@lemmy.world 17 points 6 days ago

i just want fiber at my address

[-] Kazumara@discuss.tchncs.de 35 points 6 days ago

Funny how many here took this to be real, judging from the reactions. To me it's an obvious joke.

Question to you guys: How do you suppose 200 million customers will share the less than 65'536 ports that are available on that one address?

[-] Auth@lemmy.world 21 points 6 days ago
[-] Fred@programming.dev 19 points 6 days ago

As @shane@feddit.nl says, you can use the same public port for many different destination address, vendors may call it something like "port overloading".

More importantly, you can install a large pool of public address on your CGNAT. For instance if you install a /20 pool, work with a 100 users / public address multiplexing, you can have 400,000 users on that CGNAT. 100 users / address is a comfortable ratio that will not affect most users. 1000 users / address would be pushing it, but I'm sure some ISP will try it.

If you search for "CGNAT datasheet" for products you can deploy today, the first couple of results:

[-] Kazumara@discuss.tchncs.de 11 points 6 days ago

As @shane@feddit.nl says, you can use the same public port for many different destination address, vendors may call it something like “port overloading”.

I just responded to him on that point, while you were typing to me. I didn't know this existed, thanks for pointing it out!

More importantly, you can install a large pool of public address on your CGNAT. For instance if you install a /20 pool, work with a 100 users / public address multiplexing, you can have 400,000 users on that CGNAT. 100 users / address is a comfortable ratio that will not affect most users. 1000 users / address would be pushing it, but I’m sure some ISP will try it.

Sure, yeah, I have seen a few threads on NANOG about the NAT address ratios people are using. I also think I remember someone saying he was forced to use 1000 and it kind of worked as long as he pulled the heaviest users out of the pool. But if I recall correctly he was also saying he made IPv6 available in parallel to reduce the CGNAT load.

But the point that made this post ridiculous and an obvious joke is that it said "one address" :-)

[-] Fred@programming.dev 5 points 6 days ago

Well the "one address" bit sure :) but given the scale supported by CGNAT systems today, I don't think being able to support an entire country behind a single cluster is that far off. At which point the difficulty becomes "is the 100.64.0.0/10 block big enough"? Or maybe they're using DS-lite for the hauling from private network to the NAT.

[-] Sebbe@lemmy.sebbem.se 17 points 6 days ago

Easily doubled by assigning the TCP and UDP ports to different users!

[-] shane@feddit.nl 9 points 6 days ago

A TCP session is a unique combination of client IP, client port, server IP, and server port.

So you can use the same IP and port as long as the destination is a different IP or port.

This means that in principle you could use the same IP and port to connect to every IP address on the Internet using 65536 concurrent sessions. 😆

This wouldn't help going to popular destinations, since they have a lot of people going to the same IP address and port, but for many (most?) of them you probably have some sort of CDN servers in your data centers anyway.

[-] Kazumara@discuss.tchncs.de 4 points 6 days ago

A TCP session is a unique combination of client IP, client port, server IP, and server port. So you can use the same IP and port as long as the destination is a different IP or port.

Fair point! I wasn't aware of any NAT working that way, but they could exist, I agree. It does blow up the session table a bit, but we are taking about a hell of a large theoretical system here anyway, so it's not impossible.

This wouldn’t help going to popular destinations, since they have a lot of people going to the same IP address and port, but for many (most?) of them you probably have some sort of CDN servers in your data centers anyway.

Actually we have recently seen a few content providers not upgrading their cache servers and instead preferring to fall back to our PNIs (which to be fair are plenty fast and have good enough latencies). On the other hand others made new ones available recently. Seems there isn't a universal best strategy the industry is converging on at the moment.

[-] A_norny_mousse@feddit.org 8 points 6 days ago

By creating new protocols that then become new quasi-standards that every system has to integrate because "everybody else does it too"?

(and yeah this one is a joke - ridiculing something that really exists by exaggerating it)

[-] LaggyKar@programming.dev 23 points 6 days ago

I know this is humor, but for the record this wouldn't work. Each simultaneous TCP connection needs a unique four-tuple (source address, source port, destination address, destination port). If a lot the people behind the NAT try to connect to the same place (destination address and port) at the same time (something popular like Google, YouTube or Netflix), and their source address is the same, the source port needs to be different for each connection. So after at most 65535 connections within a short time the NAT would run out of ports and no one behind the same NAT would be able to open new connections to the same place until the NAT mapping expiries.

So you could have at most tens of thousands of people behind the same NAT, maybe even fewer to make it reliable.

[-] Fred@programming.dev 11 points 6 days ago

Don't forget the tech giants are all IPv6 enabled. Google Netflix Apple xhamster Facebook Microsoft are all reachable over v6.

[-] FEIN@lemmy.world 10 points 6 days ago

I think one of these tech giants sounds wrong? It's Meta not Facebook

[-] bss03@infosec.pub 3 points 6 days ago

It's Alphabet not Google, yeah?

[-] LaggyKar@programming.dev 8 points 6 days ago* (last edited 6 days ago)

OK, bad examples. On the other hand e.g. X, GitHub, Pornhub, PSN, Steam or Discord do not support IPv6.

[-] Bane_Killgrind@lemmy.dbzer0.com 5 points 6 days ago

Guess I should start using xhamster over PH for tech puritism reasons

[-] szczuroarturo@programming.dev 1 points 4 days ago

Really discord. Didint discord start existing when ipv6 was becoming more and more normalised unlike the rest of those examples.

[-] judgyweevil@feddit.it 15 points 6 days ago

Literal spaghetti

[-] beemikeoak@lemmynsfw.com 6 points 5 days ago

Shit is that my computer's rear end? I haven't looked in there for years! There could be intelligent rats back there pretending to be AI.

[-] ulterno@programming.dev 4 points 5 days ago

Definitely not mine. It's way too clean.

stupid question, wouldn't it be easier to just have sub addresses?

like my fictional ip address is 123.123.123

and I can set my router to give up to 1000 sub addresses, so one computer can host a Minecraft server at 123.123.123.001 I have another for my some projects, the projects ones each have sub addresses like 123.123.123.002.001 and 123.123 123.002.002...

a company could have countless layers and any amount of addresss they want.

and we're never going to run out of addresses.

[-] Xylight@lemdro.id 18 points 6 days ago

Well the IPv4 spec only allows 4 octets, so having 5 or more is impossible. We could fix it by changing the protocol, but at that point it's more worth it to just migrate to IPv6.

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[-] kionite231@lemmy.ca 4 points 6 days ago

Is the news real? :o

[-] Fontasia@feddit.nl 3 points 6 days ago

Fuck whoever chose to make the acronym the same, but this is already possible by being a terrible person and sticking PAT behind traditional NAT

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this post was submitted on 03 Aug 2025
488 points (99.8% liked)

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