Slow and Fast IP addresses on http ?

Tue Jun 17 17:28:52 UTC 2003

In message <g3u1aovd6e.fsf at sa.vix.com>, Paul Vixie writes:
>
>smb at research.att.com ("Steven M. Bellovin") writes:
>
>> It might also be port 113 -- some sites try to query your tcp port 113, 
>> and wait for a timeout if the port is firewalled.  A better solution 
>> than blocking it is to send an immediate RST.
>
>people who depend on tcp/113 deserve everything stupid that happens to them.
>dropping SYN packets or returning a fixed string are both better than sending
>an immediate RST.  (false confidence being valued less than low confidence.)
>i was rather shocked to discover tcp/113 clientness enabled by default in
>postfix and sendmail.  but even widespread ignorance does not call for
>widespread coddling such as returning immediate RST's.

I'm not defending the practice, I'm defending myself against the 
practitioners.  My email, etc., was being delayed because the site I 
was sending to was trying to query my non-existent tcp/113 server, and 
I was dropping SYNs.  Now, I either send an immediate RST or use Erik 
Fair's identd, depending on my mood.

		--Steve Bellovin, http://www.research.att.com/~smb (me)
		http://www.wilyhacker.com (2nd edition of "Firewalls" book)