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Date: Fri, 14 Feb 1997 09:23:52 -0800 (PST)
From: "Tom Mueller" <trm@i-planet.com>
Reply-To: trm@i-planet.com
To: FreeBSD-gnats-submit@freebsd.org
Subject: TUNMTU limits MRU in tun device even if mtu set
X-Send-Pr-Version: 3.2

>Number:         2733
>Category:       misc
>Synopsis:       TUNMTU limits MRU in tun device even if mtu set
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:
>Keywords:
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Feb 14 09:20:01 PST 1997
>Closed-Date:    Fri Feb 21 09:35:43 PST 1997
>Last-Modified:  Fri Feb 21 09:37:29 PST 1997
>Originator:     "Tom Mueller"
>Release:        FreeBSD 2.1-STABLE i386
>Organization:
i-Planet, Inc.
>Environment:

2.1 kernel built with the tun driver (if_tun.c)

>Description:

The TUNMTU variable in if_tun.h is used to initialize the value of
if_mtu in the tun driver and to limit the size of incoming packets
in the tunwrite function.  The TUNSIFINFO ioctl can be used to 
set the value of if_mtu to something different from TUNMTU, but
TUNMTU is still used to limit the size of incoming packets.

It seems that the tunwrite function should use if_mtu to limit
incoming packet size rather than TUNMTU.

>How-To-Repeat:

This problem can be seen using the user level ppp program (iij-ppp)
when the mru is set to greater than the value of TUNMTU.

>Fix:
	
Change TUNMTU to ifp->if_mtu in the tunwrite function.

>Release-Note:
>Audit-Trail:

From: Bill Fenner <fenner@parc.xerox.com>
To: FreeBSD-gnats-submit@freebsd.org, trm@i-planet.com
Cc:  Subject: Re:  misc/2733: TUNMTU limits MRU in tun device even if mtu set
Date: Fri, 14 Feb 1997 09:47:29 PST

 This is fixed in -current (but not in 2.2, it should probably be in
 2.2 also).  The patch at
 
 http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/net/if_tun.c?r1=1.31&r2=1.32
 
 should probably apply OK to a 2.1 if_tun.c .
 
   Bill
State-Changed-From-To: open->closed 
State-Changed-By: fenner 
State-Changed-When: Fri Feb 21 09:35:43 PST 1997 
State-Changed-Why:  
Fixed in 2.2 and -current. (rev 1.29.2.2 and 1.32 of if_tun.c) 
>Unformatted:
