Go Back   DaemonForums > OpenBSD > OpenBSD General

OpenBSD General Other questions regarding OpenBSD which do not fit in any of the categories below.

Thread Tools Display Modes
  #1   (View Single Post)  
Old 29th December 2018
gustaf gustaf is offline
Fdisk Soldier
Join Date: Dec 2016
Posts: 65
Default ifconfig scan -- some networks are missing

When I run $ ifconfig iwn0 scan, some of the networks from around the neigborhood don't show up in the list.

Other computers in my house show a much larger list of networks. These are not OpenBSD machines. They are running Linux, Windows, and Android.

I have read the ifconfig(8) man page and also tried the following search terms in Google:
ifconfig scan site:daemonforums.org
There are references to the command, but nothing about the number of networks.

It seems that $ ifconfig iwn0 scan should be all I need to get a full list of available networks.

Please let me know if posting the output of any commands would be helpful.

Thanks to anyone who can offer assistance.
Reply With Quote
  #2   (View Single Post)  
Old 29th December 2018
jggimi's Avatar
jggimi jggimi is offline
More noise than signal
Join Date: May 2008
Location: USA
Posts: 7,639

Another search string in Google will provide more information, as it will search through one of the mailing list archive sites:"ifconfig scan openbsd site:marc.info"

This led me to a brief discussion on the tech@ mailing list specific to the iwn(4) driver:


Looking through the CVS log for src/sys/dev/pci/if_iwn.c, I can see that this was committed as revision 1.200, then fixed due to a regression in revision r.201. But the next commit -- 1.202 -- changes the way scans work across a broad swath of 802.11 drivers. One of these patches may be the reason for your apparent incomplete scan. You can try reverting them and build a test kernel. If reverting a patch doesn't build cleanly, you can always grab the kernel source from the CVS repository at a point in time prior to the commit.
revision 1.202
date: 2018/04/26 12:50:07; author: pirofti; state: Exp; lines: +1 -6; commitid: dXAOUb33rnol1noX;
net80211: stub SIOCS80211SCAN, make ifconfig scan instant.

The following removes the functionality of the SIOCS80211SCAN ioctl.
After long discussions with stps@, mpi@, and deraadt@ we decided that
this was the correct way of fixing ifconfig scan from blocking the
network stack.

The kernel will continue scanning in the background and filling the
nodes array, but ifconfig scan commands will now basically do just a
SIOCG80211ALLNODES and pretty print the array. So the output stays the
same but is instant.

In fact, when the interface is freshly brought up, if you type fast
enough, you can see the array being filled by running multiple ifconfig
scans in sequence.

The SIOCS80211SCAN ioctl stays for now as wi(4), pgt(4) and malo(4)
still need it around. But not for long...

Another change that this introduces is the fact that ifconfig scan no
longer plays with UP and DOWN. If the interface is down it complains and
exits. This is needed in order to maintain the nodes list.

Works on iwm(4), iwn(4), urtwn(4), run(4) and athn(4).

Tested by mpi@, landry@, florian@, thanks!
OK mpi@.

Last edited by jggimi; 29th December 2018 at 02:31 PM. Reason: clarity, typos
Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
cannot scan with cupsd+saned brudan OpenBSD Packages and Ports 4 16th December 2018 01:25 AM
Wireless scan output Mircho FreeBSD General 2 27th September 2013 12:15 PM
Bock Norton security scan! xmorg Other OS 8 15th February 2011 03:12 PM
Please scan softly - your router could crash J65nko News 2 5th July 2010 11:36 PM
scan to pdf PatrickBaer Other OS 4 22nd July 2008 12:14 AM

All times are GMT. The time now is 04:36 AM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Content copyright © 2007-2010, the authors
Daemon image copyright ©1988, Marshall Kirk McKusick