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Inital NICK followed by PING?

Posted: Sun Jul 28, 2013 11:21 pm
by n4b
I've noticed UnrealIRCD will issue a ping request to the client after the initial nick command during connection registration. The server parameter of the ping request seems to a random hexadecimal number. I was wondering what the purpose of this was? The RFC does not specify this behavior (or I couldn't find it).

Re: Inital NICK followed by PING?

Posted: Mon Jul 29, 2013 12:26 am
by Jobe1986
It's part of a solution that prevents IP spoofing.

The way it works is, if a client spoofs it's IP (complicated and technical and not related to the WEBIRC command) the client won't be able to connect as it will not be able to receive the PING command it needs to respond to before it can connect. The reason for that is because any messages sent from the server to the client are sent to the IP that the client spoofed, and not to the actual IP of the client.

Now before anyone comments on that, please note that was a dumbed down simplified explanation that avoids as much technical detail as possible.