Problem with the ROAM wpa_cli command and external scans.

Ben Greear greearb at
Thu Jul 9 09:13:07 EDT 2015

On 07/08/2015 03:59 PM, Ben Greear wrote:
> Previously (or so I believe), I could request a scan using 'iw', and then
> tell wpa_cli to do a roam now than the scan is fresh.  I let user specify
> the channels to scan with iw so that I can minimize scan time..which is a big help
> when doing lots of virtual stations.
> But, now it seems wpa_supplicant ignores these external scans.
> Is there a better way to fix this other than to just hack wpa_supplicant
> to have an override that allows it to use external scan results?
> 1436395475.329812: nl80211: Event message available
> 1436395475.329858: nl80211: Drv Event 33 (NL80211_CMD_TRIGGER_SCAN) received for sta100
> 1436395475.329875: sta100: nl80211: Scan trigger
> 1436395475.329888: sta100: Event SCAN_STARTED (47) received
> 1436395475.329901: sta100: External program started a scan
> 1436395475.359732: RTM_NEWLINK: ifi_index=10 ifname=sta100 wext ifi_family=0 ifi_flags=0x1003 ([UP])
> 1436395475.359792: nl80211: Event message available
> 1436395475.359815: nl80211: Drv Event 34 (NL80211_CMD_NEW_SCAN_RESULTS) received for sta100
> 1436395475.359831: sta100: nl80211: New scan results available
> 1436395475.359839: nl80211: Scan probed for SSID ''
> 1436395475.359864: nl80211: Scan included frequencies: 5180
> 1436395475.359872: sta100: Event SCAN_RESULTS (3) received
> 1436395475.359882: sta100: Scan completed in 0.029981 seconds
> 1436395475.359961: nl80211: Received scan results (5 BSSes)
> 1436395475.360053: sta100: BSS: Start scan result update 10
> 1436395475.360075: BSS: last_scan_res_used=5/32
> 1436395475.360084: sta100: New scan results available (own=0 ext=1)
> 1436395475.360099: sta100: Do not use results from externally requested scan operation for network selection
> 1436395477.423911: sta100: Control interface command 'ROAM 04:F0:21:98:D2:34'
> 1436395477.423949: CTRL_IFACE ROAM 04:f0:21:98:d2:34
> 1436395477.423958: CTRL_IFACE ROAM: No network configuration known for the target AP

After reading the code more closely, this last error message actually just
appears to mean that the station is not currently associated, and one cannot roam
when not already associated?

Maybe we should automatically try to do a 'RECONNECT' in this case?

In general, it would be nice if wpa_cli had a way to pass very specific error strings
or codes + string back to the calling program..that way calling code could be made to know the
exact failure reasons and take appropriate action...  Any suggestions as to how to go
about doing this?


> Thanks,
> Ben

Ben Greear <greearb at>
Candela Technologies Inc

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