Subject: kern/23694: monitor mode is broken with wi(4)
To: None <>
From: None <>
List: netbsd-bugs
Date: 12/08/2003 20:22:05
>Number:         23694
>Category:       kern
>Synopsis:       monitor mode is broken with wi(4)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 08 20:23:00 UTC 2003
>Originator:     David Young
>Release:        NetBSD 1.6ZG
OJC Technologies
System: NetBSD 1.6ZE NetBSD 1.6ZE (GENERIC.ath) #2: Sun Nov  9 12:32:52 CST 2003 i386
Architecture: i386
Machine: i386
     $NetBSD: wi.c,v 1.143 2003/11/02 01:55:40 dyoung Exp $
     $NetBSD: ieee80211.c,v 1.7 2003/10/16 22:25:00 matt Exp $
     $NetBSD: ieee80211_compat.c,v 1.3 2003/09/23 15:57:25 dyoung Exp $
     $NetBSD: ieee80211_crypto.c,v 1.4 2003/09/23 16:03:46 dyoung Exp $
     $NetBSD: ieee80211_input.c,v 1.14 2003/10/27 17:11:19 mycroft Exp $
     $NetBSD: ieee80211_ioctl.c,v 1.5 2003/10/13 20:05:09 dyoung Exp $
     $NetBSD: ieee80211_node.c,v 1.8 2003/11/02 01:29:05 dyoung Exp $
     $NetBSD: ieee80211_output.c,v 1.9 2003/11/02 00:17:27 dyoung Exp $
     $NetBSD: ieee80211_proto.c,v 1.5 2003/10/13 04:23:56 dyoung Exp $
When you put a Lucent wi(4) into monitor mode, no packets (or else very few)
are available to the Berkeley Packet Filter tap. The problem seems to be that
packets received in monitor mode meet at zero or more "drop" criteria for wi,
and also at least one drop criterion for the 802.11 layer.
ifconfig wi0 mediaopt monitor
ifconfig wi0 chan <a channel where there is 802.11b activity>
tcpdump -ne -y ieee802_11 -i wi0
The problem needs more analysis, but make the drop criteria less stringent
for monitor mode.