From:	alan@lxorguk.ukuu.org.uk (Alan Cox)
Subject: Re: 2.0.34 BUG: TCP KeepAlive processing
To:	robn@verdi.et.tudelft.nl (Rob van Nieuwkerk)
Date:	Sun, 7 Jun 1998 16:23:07 +0100 (BST)

> This change in behaviour is related to a change in net/ipv4/tcp_input.c:
> the last statement of tcp_ack() was changed from "return 1;" to
> "return 0;" in 2.0.34 (line 1728).  Changing it back to the 2.0.33
> one gives back the wanted behaviour.

Yep. The problem is putting it back to the 2.0.33 behaviour also allows a
third party using only remote packet counts (eg snmp access) to find the
sequence number of a tcp session and attack it. (Linux and other OS's)

I'll look at work arounds in .35 - the obvious one is to ack just 1 byte
out of window in the direction used by old BSD keepalives.

Alan

-
To unsubscribe from this list: send the line "unsubscribe linux-net" in
the body of a message to majordomo@vger.rutgers.edu