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Subject: Re: How can I prevent outside users from telnet directly to the postf ix server?
From: David Terrell (dbtmeat.net)
Date: Mon Oct 09 2000 - 18:01:42 CDT

On Tue, Oct 10, 2000 at 09:35:46AM +1100, Ben Elliston wrote:
> I *could* add telnet options negotiation support to the Postfix SMTP
> server, and thus detect that the client is using telnet. But the
> Postfix SMTP server program is already much too large.
>
> I did this to sendmail 8.7.x. It worked great, but as Eric Allman pointed
> out, it doesn't stop people for long. A 5 line Tcl script could be written
> to attack your SMTP server instead, bypassing the Telnet protocol detection.

Especially since most telnet clients I know of don't send telnet negotiation
to ports other than 23. 

-- 
David Terrell             | "War is peace, 
Prime Minister, Nebcorp   | freedom is slavery, 
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