Re: IRC slowness and firewall

From: amputee (dirty@pakistani.com)
Date: 04/21/02 

From: "amputee" <dirty@pakistani.com>
Date: Sun, 21 Apr 2002 19:24:45 GMT

"El Brujo" <me@bigfoot.com> wrote in message news:bgt5cukf6n1j58q506f9c2eoj4srtev2f5@4ax.com...
>
> I'm using Kerio and I noticed that when the firewall is active, mIRC
> takes a lot of time to connect to the irc server, but it connects
> almost instantaneously when Kerio is off. I have a simple rule to
> allow mIRC to connect to any IP at port 6667 (IRC standard) through
> TCP, so what's the problem?
>
> Anyone can help?
>
> TIA

This is probably because most IRC servers authenticate by connecting
to your host on port 113 (identd/authentication) if Kerio is running,
this port is blocked, and no ident response is returned. Also, and I'm
taking a guess here, Kerio probably silently drops SYNs, some
firewall manufacturers call this "stealth" mode or something similar.
Normally when your machine receives a SYN and the port is closed,
a RST is sent, but in this mode, nothing will be sent, so the server will
wait a default amount of time for the packet to time out.

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