Bug 1415717 - iwlist scan fails with too many AP
Summary: iwlist scan fails with too many AP
Alias: None
Product: Fedora
Classification: Fedora
Component: wireless-tools
Version: 25
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Lubomir Rintel
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2017-01-23 14:13 UTC by Henrique Martins
Modified: 2017-12-12 10:47 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
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Clone Of:
Last Closed: 2017-12-12 10:47:38 UTC
Type: Bug

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Description Henrique Martins 2017-01-23 14:13:15 UTC
Description of problem:
iwlist scan aborts when too many access points are nearby

Version-Release number of selected component (if applicable):

How reproducible:
Every time, in the above situation, which happens to me when I go to Paris and stay with my sister-in-law, first time 4 years ago, still a problem this year.

Steps to Reproduce:
1. Go to a place with too many access points
2. run iwlist scan to find out available networks

Actual results:
iwlist aborts with error message

Expected results:
A list of available APs

Additional info:
It is a well know bug, supposedly fixed in wireless_tools.30.pre9.
There also seems to be a patch referenced at the bottom of this page
Can't really help debugging this, unless someone pays me to fly back there :-)

Comment 1 Dan Williams 2017-01-23 17:10:45 UTC
The patch may help some situations, and we could potentially apply it to wireless-tools.  However, it only works to a certain point, and it is already common to overflow a 64k buffer with the WEXT scan request.  Unfortunately, this cannot easily be fixed in wireless-tools due to the older non-extensible nature of the kernel's WEXT API.

I would suggest that instead of 'iwlist wlan0', you use 'iw dev wlan0 scan' which is the replacement that uses the much more extensible nl80211 kernel API.

I'd also recommend using 'iw' for anything you previously used iwconfig/iwlist/iwevent/etc for, as it is a much more capable tool and supports many of the options that the iwconfig tools cannot due to their older API.

You may have a wifi card whose driver doesn't support nl80211, but these are a small minority.  If you do, however, there is no good solution except to ask the provider of that wifi card (or the upstream kernel community) to add nl80211 support to that driver.

Comment 2 Fedora End Of Life 2017-11-16 19:22:31 UTC
This message is a reminder that Fedora 25 is nearing its end of life.
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Comment 3 Fedora End Of Life 2017-12-12 10:47:38 UTC
Fedora 25 changed to end-of-life (EOL) status on 2017-12-12. Fedora 25 is
no longer maintained, which means that it will not receive any further
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