NetBSD Problem Report #8052

Received: (qmail 21311 invoked from network); 24 Jul 1999 02:39:24 -0000
Message-Id: <199907240239.XAA03040@mateus.ppires.org>
Date: Fri, 23 Jul 1999 23:39:18 -0300 (EST)
From: pappires@ppires.org
Reply-To: pappires@ppires.org
To: gnats-bugs@gnats.netbsd.org
Subject: wrong behaviour of packet filtering over PPP interfaces
X-Send-Pr-Version: 3.95

>Number:         8052
>Category:       lib
>Synopsis:       wrong behaviour of packet filtering over PPP interfaces
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    lib-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 23 19:50:01 +0000 1999
>Closed-Date:    Wed Jul 28 01:35:13 +0000 1999
>Last-Modified:  Wed Jul 28 01:35:54 +0000 1999
>Originator:     Paulo A. P. Pires
>Release:        NetBSD-current 1999/07/20
>Organization:
	Familia Pires
>Environment:
System: NetBSD mateus.ppires.org 1.4G NetBSD 1.4G (MATEUS-19990720) #0: Wed Jul 21 00:44:28 EST 1999 Pappires@mateus.ppires.org:/usr/src/sys/arch/i386/compile/MATEUS-19990720 i386
/usr/lib/libpcap.a
/usr/lib/libpcap.so
/usr/lib/libpcap.so.1
/usr/lib/libpcap.so.1.0
/usr/lib/libpcap_p.a
/usr/lib/libpcap_pic.a
IPF/NAT enabled.
ne1 installed as 0x300/10, modem is USR Sportster 33600 internal.
Tried with kernels with both IPv6 enabled and disabled, with same results.


>Description:
	Trying to use packet filters on PPP interfaces produces wrong
	results for any filtering expression other than default.  The
	problem doesn't seem to occur over ethernet interfaces ever,
	with similar expressions or even much more complex ones.

	This affects both tcpdump and pppd active/pass filters, so it
	makes me think that the problem is in libpcap (but perhaps it
	is in kernel bpf/ppp implementation?).

	This problem is prticularly annoying because it renders dial
	on demand PPP filtering unusable.

	This problem has been happening with my i386 machines since
	at least 1.4E (never noticed it until 1.4C).

>How-To-Repeat:
	# ping any_host_accross_ppp_link      (or any network app.)

	[switch to another tty]

	# tcpdump -n -i ppp0 host any_host_accross_ppp_link
	[ no packages will be shown ]

>Fix:
	Unknown.
>Release-Note:
>Audit-Trail:

From: itojun@iijlab.net
To: pappires@ppires.org
Cc: gnats-bugs@gnats.netbsd.org
Subject: Re: lib/8052: wrong behaviour of packet filtering over PPP interfaces 
Date: Sun, 25 Jul 1999 02:27:45 +0900

 >>Synopsis:       wrong behaviour of packet filtering over PPP interfaces
 >>How-To-Repeat:
 >	# ping any_host_accross_ppp_link      (or any network app.)
 >	[switch to another tty]
 >	# tcpdump -n -i ppp0 host any_host_accross_ppp_link
 >	[ no packages will be shown ]

 	Could I see the output of the following commands:
 	# tcpdump -n -i ppp0 -e -s 2000 -x
 	# tcpdump -n -i ppp0 -e -s 2000 -x -d
 	# tcpdump -n -i ppp0 -e -s 2000 -x host any_host_across_ppp_link
 	# tcpdump -n -i ppp0 -e -s 2000 -x -d host any_host_across_ppp_link

 	Thanks,

 itojun
State-Changed-From-To: open->closed 
State-Changed-By: itojun 
State-Changed-When: Tue Jul 27 18:35:13 PDT 1999 
State-Changed-Why:  
submitter confirmed. 
this was due to inconsistency in net/if_ppp.c and libpcap prior to IPv6 merge. 
>Unformatted:

Home	PR Database Search