wpa_supplicant and strongest BSSID

Discussion:

(too old to reply)

William Unruh

2022-06-23 01:39:32 UTC

wpa_supplicant has a bad bug. If there are many BSSID for a single SSID,
wpa_supplicant will simply grab the first BSSID it sees to connect to.
This can often (usualy) be a disaster, as it will grab a weak signal,
rather than the strongest signal, meaning lots of disconnections, flakey
wifi, etc. Does anyone know of a way to get it to grab the strongest
signal (Yes, I know what the strongest is may fluctuate, but it is
better to grab a signal that is now strong, rather than grab a very weak
BSSID)
The BSSID is the hadware address of a given wifi access point, while the
SSID is the name of the network that that access point is supposed to
connect to. Thus at a University there may be many BSSID all of which
connect to the eduroam network. Or in a Hotel, there may be many access
points all of which have the same name "Hilton Bombay" but being from
different floors of the hotel, will vary widely in strength.
wpa_supplicant just grabs the first one it sees, which could be from 3
floors away with a signal strength of "one bar" and completelydisappears
when someone on the intermediate floors takes a bath (the water
reflecting the signal). This is instead of using the signal from the AP
just outside the door of your room on your floor.

Herman Viaene

2022-06-23 08:29:32 UTC

Permalink

Post by William Unruh
wpa_supplicant has a bad bug. If there are many BSSID for a single SSID,
wpa_supplicant will simply grab the first BSSID it sees to connect to.
This can often (usualy) be a disaster, as it will grab a weak signal,
rather than the strongest signal, meaning lots of disconnections, flakey
wifi, etc. Does anyone know of a way to get it to grab the strongest
signal (Yes, I know what the strongest is may fluctuate, but it is
better to grab a signal that is now strong, rather than grab a very weak
BSSID)
The BSSID is the hadware address of a given wifi access point, while the
SSID is the name of the network that that access point is supposed to
connect to. Thus at a University there may be many BSSID all of which
connect to the eduroam network. Or in a Hotel, there may be many access
points all of which have the same name "Hilton Bombay" but being from
different floors of the hotel, will vary widely in strength.
wpa_supplicant just grabs the first one it sees, which could be from 3
floors away with a signal strength of "one bar" and completelydisappears
when someone on the intermediate floors takes a bath (the water
reflecting the signal). This is instead of using the signal from the AP
just outside the door of your room on your floor.

Any particular reason why you prefer the command i.s.o. using MCC -
Network Center???

Herman Viaene

William Unruh

2022-06-23 10:06:43 UTC

Permalink

Post by Herman Viaene

Post by William Unruh
wpa_supplicant has a bad bug. If there are many BSSID for a single SSID,
wpa_supplicant will simply grab the first BSSID it sees to connect to.

...

Post by Herman Viaene
Any particular reason why you prefer the command i.s.o. using MCC -
Network Center???

I do use Network Center. It uses wpa_supplicant to do the actual
connection. And wpa_supplicant behaves badly. You can see that in the
Network Center window. The SSIDs are listed in order of signal strength.
If you have many BSSIDs for one SSID name, you will have many entries
for that name in the list. Click on the highest one, and hit connect.
Once it has connected it will highlight the one that was connected to
(ie the BSSID that was actually used). It is often/usually NOT the top
(strongest) It may well be the 5th or 7th one down the list (scroll down
the on list in the Network Center window list until you see the
highlighted one). That has a much weaker signal than the connected one.

For example I have 11 "eduroam" Access points listed in Network center
(Each a separate BSSID Access point).
I clicked on the top one (signal strenght 100) and clicked on Connect.
It connected to the 7th one down-- signal strength 47%.
Sometimes it does connect to the strongest, but rarely if there are a
lot of them.

Looking at wpa_supplicant debug output (edit
/etc/sysconfig/network-script/ifup-eth
and put a "-dd -t -f /var/log/wpa_supplicant" into the main wpa_supplicant
call [the command starts with
/usr/sbin/wpa_supplicant -B -i ${DEVICE} \
]

you can see wpa_supplicant going through the the various access points
it has found, but not in any particular order and certainly not in order
of signal strength. It seems to simply go in the random order of which
access points it has seen first.

And yes, this is using NetworkCenter (which uses the proograms in
/etc/sysconfig/network-script)

David W. Hodgins

2022-06-23 17:54:45 UTC

Permalink

Post by Herman Viaene

Any particular reason why you prefer the command i.s.o. using MCC -
Network Center???

The command is used by drakxnet. The bug has been reported
https://bugs.mageia.org/show_bug.cgi?id=23453
but after almost 4 years, no change.

Regards, Dave Hodgins

William Unruh

2022-06-24 06:06:54 UTC

Permalink

Post by David W. Hodgins

Post by Herman Viaene

Any particular reason why you prefer the command i.s.o. using MCC -
Network Center???

The command is used by drakxnet. The bug has been reported
https://bugs.mageia.org/show_bug.cgi?id=23453
but after almost 4 years, no change.

Yes. Unfortunately the person who wrote the NetworkCenter suite skipped
town about 3 years ago, and noone else has stepped in. It is such a
crucial part of laptops that it would be really great if someone
stepped in. I would have but I do not know Perl. And my coding skills
have never been the greatest (Inability to imagine all of the ways the
code could break is one problem I have, which is a key aspect of coding
competence).

Also wpa_supplicant is run by an upstream which is hard to find the bug
reporting for.

Bit Twister

2022-06-23 10:23:16 UTC

Permalink

Post by William Unruh
wpa_supplicant has a bad bug.

Hope you opened a bug report so that the app maintainer knows about it,
not Mageia.

Post by William Unruh
If there are many BSSID for a single SSID,
wpa_supplicant will simply grab the first BSSID it sees to connect to.
This can often (usualy) be a disaster, as it will grab a weak signal,
rather than the strongest signal, meaning lots of disconnections, flakey
wifi, etc. Does anyone know of a way to get it to grab the strongest
signal

All I can suggest is a wrapper you create to dump desired BSSID and strength,
sort, chose, create a configuration file, then launch the connection.

for example you can run, as root,
wpa_cli -i wlp2s0 scan_results | sort -n --key=4 --key=2 | cat -n > aa

You can then read aa and build a button string to use with xmessage to
provide a selection to pick from. Example:
# cat aa
1 f4:69:42:f2:52:0f 2412 -79 [WPA2-PSK-CCMP][ESS] SpectrumSetup-11
2 40:b0:34:de:47:1e 2437 -73 [WPA2-PSK-CCMP][WPS][ESS] DIRECT-1D-HP OfficeJet 4650
3 40:b8:9a:da:b2:1e 2462 -71 [WPA2-PSK-CCMP][WPS][ESS] Ulisses-2G
4 e8:d2:ff:bc:17:e6 2412 -69 [WPA2-PSK-CCMP][ESS] SpectrumSetup-E0
5 c8:b4:22:61:06:79 2437 -65 [WPA2-PSK-CCMP][ESS] Houseofpain
6 80:cc:9c:ba:9d:0c 2452 -65 [WPA2-PSK-CCMP][WPS][ESS] NETGEAR04
7 bssid / frequency / signal level / flags / ssid

# xmessage -buttons 1,2,3,4,5,6,7 -file aa

You can use a case statement to parse $? to see/get user selection.
Ir user clicks button 5 $? will have 105

That tells the wrapper to use line 5 to build a configuration file and
launch the connection.

William Unruh

2022-06-23 12:51:42 UTC

Permalink

Post by Bit Twister

Post by William Unruh
wpa_supplicant has a bad bug.

Hope you opened a bug report so that the app maintainer knows about it,
not Mageia.

All I can suggest is a wrapper you create to dump desired BSSID and strength,
sort, chose, create a configuration file, then launch the connection.

I like Network Center. I tried Network Manager but both found it clunky
and not working sometimes and found that when things went wrong it was
really hard to figure out why.

Post by Bit Twister
for example you can run, as root,
wpa_cli -i wlp2s0 scan_results | sort -n --key=4 --key=2 | cat -n > aa
You can then read aa and build a button string to use with xmessage to
# cat aa
1 f4:69:42:f2:52:0f 2412 -79 [WPA2-PSK-CCMP][ESS] SpectrumSetup-11
2 40:b0:34:de:47:1e 2437 -73 [WPA2-PSK-CCMP][WPS][ESS] DIRECT-1D-HP OfficeJet 4650
3 40:b8:9a:da:b2:1e 2462 -71 [WPA2-PSK-CCMP][WPS][ESS] Ulisses-2G
4 e8:d2:ff:bc:17:e6 2412 -69 [WPA2-PSK-CCMP][ESS] SpectrumSetup-E0
5 c8:b4:22:61:06:79 2437 -65 [WPA2-PSK-CCMP][ESS] Houseofpain
6 80:cc:9c:ba:9d:0c 2452 -65 [WPA2-PSK-CCMP][WPS][ESS] NETGEAR04
7 bssid / frequency / signal level / flags / ssid
# xmessage -buttons 1,2,3,4,5,6,7 -file aa
You can use a case statement to parse $? to see/get user selection.
Ir user clicks button 5 $? will have 105
That tells the wrapper to use line 5 to build a configuration file and
launch the connection.

Another bug is that Network Center does not use wpa_cli as user, since
it onlyworks for root, and iwlist has the really really annoying but
that if there are too may access points(BSSID) then it reports nothing.
So, either Network center needs to be set up to be suid root (probably
not safe at the moment and I have not tried to see if that works) or it
needs to run wpa_cli always and if there are 1000 access points either
list them or pick the 50 strongest ones and report tthem in
networkcenter.

At present Network center simply does nothing if there are too many
BSSIDs.

The problem also is that if you hand wpa_supplicant an name (SSID) it
will go through that "pick a random one" process (ie a raondom BSSID
that has the right name).
One can tell wpa_supplicant to pick one BSSID to assocate with the SSID,
but what happens if for some reason that one does not work.
wpa_supplicant then blacklists it, and I have no idea what happens if
the blacklisted one is the selected one.

I really do not want to have to rewrite NetworkCenter on my own. That is
what distributions are for, so one competent person can do the work that
A million incompetent ones can use.

2022-06-24 00:04:45 UTC

Permalink

Post by William Unruh

Post by Bit Twister

Post by William Unruh
wpa_supplicant has a bad bug.

Hope you opened a bug report so that the app maintainer knows about it,
not Mageia.

All I can suggest is a wrapper you create to dump desired BSSID and strength,
sort, chose, create a configuration file, then launch the connection.

I like Network Center. I tried Network Manager but both found it clunky
and not working sometimes and found that when things went wrong it was
really hard to figure out why.

I had the same sort of problem with the Network Center, only on a MUCH
smaller scale. I have a dual-band router, and if I had both band SSIDs
configured, it would connect to the first one on the list, regardless of
which band I TOLD it to use. I switched to Network Manager where there
were dual-band adapters on the machine, and it was much better for my
setup.

But, That's me. YMMV. What I did find later on our repos was a package
called "wpa_supplicant-gui." I used it to set the connection priortity
for each band, and then I connected to the one I wanted to use.

Of course, that wouldn't work well for a laptop that was used in a
university library, then used again in a lab across campus. You'd have
to change the priority levels every time you moved. And I have no idea
how well it might work for several BSSIDs. But, it might be less
annoying than what you're dealing with now.

TJ

Herman Viaene

2022-06-24 13:34:29 UTC

Permalink

Op Thu, 23 Jun 2022 20:04:45 -0400, schreef TJ:
...snip....

Post by TJ
I had the same sort of problem with the Network Center, only on a MUCH
smaller scale. I have a dual-band router, and if I had both band SSIDs
configured, it would connect to the first one on the list, regardless of
which band I TOLD it to use. I switched to Network Manager where there
were dual-band adapters on the machine, and it was much better for my
setup.

I got around the dual band setup by giving each band a separate ESSID. My
Fritzbox router allows that, I don't know for other routers.

Herman Viaene

2022-06-24 14:59:57 UTC

Permalink

Post by Herman Viaene
...snip....

I got around the dual band setup by giving each band a separate ESSID. My
Fritzbox router allows that, I don't know for other routers.
Herman Viaene

My Linksys does, too. Mine did have different, if similar, SSIDs. But,
no matter what, if the assigned priorities were the same the Network
Center connected to the first one on the wpa_supplicant list that's
available.

TJ

William Unruh

2022-06-25 05:38:30 UTC

Permalink

Post by TJ

Post by Herman Viaene
...snip....

I got around the dual band setup by giving each band a separate ESSID. My
Fritzbox router allows that, I don't know for other routers.
Herman Viaene

Yes that's another problem with wpa_supplicant. It seems to go through
the wpa_supplicant.conf list and grab entries at random. I set up
ifup-eth to extract the appropriate name/SSID block, write it to a new
file and tell wpa_supplicant to use that file .

An ugly kludge.

Post by TJ
TJ