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Date:      Mon,  9 Oct 2000 05:32:09 -0700 (PDT)
From:      jau@iki.fi
To:        freebsd-gnats-submit@FreeBSD.org
Subject:   kern/21860: The fix to TCP_ISSINCR after the bugtraq error report could still be enhanced.
Message-ID:  <20001009123209.224F337B66C@hub.freebsd.org>

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>Number:         21860
>Category:       kern
>Synopsis:       The fix to TCP_ISSINCR after the bugtraq error report could still be enhanced.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Oct 09 05:40:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Jukka A. Ukkonen
>Release:        3.5.1
>Organization:
SysOpen Plc. / Finland
>Environment:
FreeBSD mjolnir.thunderbolt.fi 3.5.1-RELEASE FreeBSD 3.5.1-RELEASE #1: Sun Oct  8 20:16:47 EET DST 2000     jau@mjolnir.thunderbolt.fi:/usr/src/sys/compile/Mjolnir  i386

>Description:
The TCP sequence number increment used to be counted like
this

#ifndef tcp_random18
#define tcp_random18()  (random() & 0x3ffff)
#endif

#define      TCP_ISSINCR     (122*1024 + tcp_random18())

which was then changed such that random became arc4random.
This in anyhow inferior to making the whole thing entirely
random as in

#define      TCP_ISSINCR     (arc4random())


>How-To-Repeat:

Try each of the alternative methods with nmap.


>Fix:
#define      TCP_ISSINCR     (arc4random())


>Release-Note:
>Audit-Trail:
>Unformatted:


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