But supporting SCTP has to start somewhere ? Why? [LWN.net]

But supporting SCTP has to start somewhere ? Why?

Posted Nov 25, 2009 15:36 UTC (Wed) by foom (subscriber, #14868)
In reply to: But supporting SCTP has to start somewhere ? Why? by marcH
Parent article: Reducing HTTP latency with SPDY

> Except for NATs, but NATs will disappear with the very near exhaustion of IPv4 addresses
> and the pressure of P2P applications.

No they won't. Did you see the PR disaster Apple had when the Airport Express supported IPv6
without NAT? Everyone suddenly went "OMG my internal network is all exposed to the internet now,
giant security hole!!!". And of course, they were right -- that is unexpected behavior in today's
world. So, no doubt about it, NAT will live on even with IPv6. (When I say NAT there, I really mean
connection-tracking-based filtering: tacking the address translation on is trivial to do or not, but
it's the connection-tracking which would cause problems with SCTP).

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But supporting SCTP has to start somewhere ? Why?

Posted Nov 25, 2009 18:57 UTC (Wed) by smurf (subscriber, #17840) [Link]

>> When I say NAT there, I really mean connection-tracking-based filtering

So why do you call it NAT, if no address is actually translated?

But supporting SCTP has to start somewhere ? Why?

Posted Nov 25, 2009 23:55 UTC (Wed) by foom (subscriber, #14868) [Link]

Because when people say "XXX is broken because of NAT", they actually mean "XXX is broken because of stateful connection tracking and filtering".

They just say "NAT" because stateful connection tracking and filtering is an integral part of NAT, and NAT is the most use. Of course it's possible to do a the connection-tracking without the address rewriting, but the important thing to note it is not any less complex, and causes no fewer problems.

It still prevents you from having an end-to-end internet.

You still want to have protocol-specific parsing in order to find "related" connections which should be allowed through. (e.g. with FTP). You'd still need a protocol like uPNP or NAT-PMP in order to advise the firewall to open a hole for things like BitTorrent. There's almost no advantage at that point versus actually having a NAT.

But supporting SCTP has to start somewhere ? Why?

Posted Nov 26, 2009 7:57 UTC (Thu) by smurf (subscriber, #17840) [Link]

>> There's almost no advantage at that point versus actually having a NAT.

Sure there is.

You avoid starving the router of TCP (or SCTP) ports. You avoid having to mangle TCP packets because they happen to contain addresses. You avoid IP address based "one-connection-per-client" limits on servers.

In short, you can use simpler servers and routers. Which translates to fewer bugs and less power-hungry CPUs.

But supporting SCTP has to start somewhere ? Why?

Posted Nov 25, 2009 23:45 UTC (Wed) by marcH (subscriber, #57642) [Link]

You are talking about default settings. I am talking about what is to become possible. Both are interesting, but quite different.