Date: Mon, 9 Dec 2002 13:26:45 +0100 (CET) From: Andre Albsmeier <andre.albsmeier@mchp.siemens.de> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/46123: PATCH: tcpdump needs -a flag if netmask is set to 0xffffffff Message-ID: <200212091226.gB9CQjJc046365@curry.mchp.siemens.de>
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>Number: 46123
>Category: bin
>Synopsis: PATCH: tcpdump needs -a flag if netmask is set to 0xffffffff
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Mon Dec 09 04:30:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Andre Albsmeier
>Release: FreeBSD 4.7-STABLE i386
>Organization:
>Environment:
System: 4.7-STABLE FreeBSD #0: Fri Nov 29 09:27:20 CET 2002
>Description:
If the -a flag was not specified tcpdump doesn't convert network and
broadcast addresses to names. However, it treats everything as a
broadcast address if the interface has a netmask of 0xffffffff (recent
versions of ppp set the netmask to 0xffffffff for the tun0 interface).
This means that even non-broadcast/network destined traffic won't
get their addresses converted.
>How-To-Repeat:
If you use a recent version of ppp the netmask should be 0xffffffff:
andre@gate:~>ifconfig tun0
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
inet 217.88.xxx.yyy --> 217.5.98.95 netmask 0xffffffff
Opened by PID 15634
If you run a tcpdump on tun0 (without -a) you see your traffic
but it won't be converted to names.
>Fix:
The patch disables the check for broadcast/network addresses if the
netmask is set to 0xffffffff:
--- contrib/tcpdump/addrtoname.c.ORI Thu Sep 12 09:56:44 2002
+++ contrib/tcpdump/addrtoname.c Sat Sep 14 12:35:10 2002
@@ -200,6 +200,7 @@
if (!nflag &&
(addr & f_netmask) == f_localnet &&
(aflag ||
+ netmask == 0xffffffff ||
!((addr & ~netmask) == 0 || (addr | netmask) == 0xffffffff))) {
if (!setjmp(getname_env)) {
(void)setsignal(SIGALRM, nohostname);
>Release-Note:
>Audit-Trail:
>Unformatted:
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