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To: Robert Chalmers <robert@nanguo.chalmers.com.au>
cc: freebsd-questions@freebsd.org (bsd), freebsd-isp@freebsd.org (FreeBSD ISP),
        bugs@freebsd.org
Subject: Re: I give up! no ideas left. 
In-reply-to: Your message of "Sun, 09 Feb 1997 09:09:47 +1000."
             <199702082309.JAA00202@nanguo.chalmers.com.au> 
Date: Sun, 09 Feb 1997 11:37:29 +0800
From: Peter Wemm <peter@spinner.DIALix.COM>
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Robert Chalmers wrote:
> The saga of failing connections to my web site. Some do, some dont.
> 2.1.5 will, 2.2 wont. Anything SUN based also seems to barf. I dont
> know about the rest. Some connect and hang. 5000 a month on average
> have no problems at all!!!

Have you tried turning off the transaction tcp code?  (see RFC1323 and RFC1644)

In /etc/sysconfig:
#
# Some broken implementations can't handle the RFC 1323 and RFC 1644
# TCP options.  If TCP connections randomly hang, try disabling this,
# and bug the vendor of the losing equipment.
#
tcp_extensions=YES

Changing YES to NO and rebooting is the permanent way.

Or, you can do this at run time without a reboot to test it:
sysctl -w net.inet.tcp.rfc1323=0
sysctl -w net.inet.tcp.rfc1644=0

Did you mention an Annex in the pathway?  I understand they are known to 
cause problems with T/TCP headers.

On http://www.noao.edu/~rstevens/ttcp.html I see:

Implementations that Interact Poorly with T/TCP
 * Solaris, through and including 2.5. See Section 3.7 of TCP/IP Illustrated,
   Volume 3 for details.  
 * AIX 4.1.2. Earlier versions, specifically 3.2.2, handled SYN/data/FIN
   segments correctly. 
 * Annex terminal servers. These don't like SYN segments with FIN or data.
   This botch extends to their SLIP/PPP implementation (perhaps only when
   doing VJ compression), so that T/TCP across an Annex acting as a dialup
   SLIP server fails even if both ends are capable. 
 * Linux. 
 * KA9Q. 

This page is from the author of the TCP/IP Illustrated series, 
W. Richard Stevens.

Cheers,
-Peter