Re: Problem with changing encryption for established connection

[代尔欣 <daierxin gmail com>]

Hi all,
   I ever met this problem and test with my own router such as changing the ssid after connection established or changing the encryption. I know this rarely happen in the actually use.
case 1:
Connect to AP "a" with wpa encrption. Then change encrption to WEP.
After changing, wait a while, then I see the connection disconnect from AP "a". If have other wireless profile, NM will try to connect(But not AP "a"). Click on applet, I will see 2 AP named with "a" in the AP list. One can connect. Another can not connect of course. After about 6 minutes, the old AP "a" disappear from the ap list. I know NM will remove the AP if it can't be found in 3 scan cycles(MAX interval is 120 seconds). But for this case, I think the 2 same AP may make user confused, if it click on the wrong one, it never connect. It better we just show one AP "a" and notify user the AP already changed.

case 2:
Connect to AP "a" with wpa encrption. Then change the AP name to "b".
After changing, wait a while, same as case 1, then I see the connection disconnect from AP "a". If have other wireless profile, NM will try to connect(But not AP "a"). Click on applet, I will see both "a" and "b" in the ap list. After about 6 minutes, "a" is disappeared. This case more confused user than case 1. User will never connect to "a"(Because they do not know "a" already changed to "b"). 

For both case, I think it better remove the changed AP immediately(if we can) and give a notify to user.

2009/11/3 Dan Williams <dcbw redhat com>

On Sat, 2009-10-31 at 13:09 +0000, Graham Lyon wrote:
> 2009/10/26 Dan Williams <dcbw redhat com>
>
>         I made that work at one point, so that if you did switch from
>         WEP to WPA
>         it would just ask and you send the new settings.  But at some
>         point I
>         think that became obsolete, because NM won't even try to
>         connect to your
>         AP if the connection is WEP, but the AP is WPA; this filtering
>         was
>         requested mainly for people with 'linksys' default-ssid APs
>         where say
>         their neighbor was running one with WEP + 'linksys', but the
>         one they
>         connected to was WPA or something.
>
>
> I'm curious about this. Are people with that model of router simply
> unable to change their SSID then? If not, surely if their neighbor's
> SSID is the same as theirs and this is causing them issues then the
> correct course of action would be to change their SSID and not cause
> everyone to lose what I personally think is an essential piece of
> functionality. Changing of encryption methods is actually quite common
> (no, I'm not saying it's done every day but it's certainly not
> unexpected behavior).

I believe there are some vendors where you can't change the SSID, or
where you aren't given access to the web interface to reconfigure.
These are mainly specific ISP devices that the ISP locks down and sends
out with "self-install" kits or whatever.

The other complication is APs that use the same BSSID but two different
SSIDs, which some Cisco devices do.  There's a "public" network that
broadcasts its SSID, and a private network with encryption that's hidden
and does not broadcast the SSID.  The same BSSID is used for both, but
they have different security settings.

Thus, we'd have to check the scan list before popping up that dialog
(asking for new security settings) to ensure that there was only one
other AP with that BSSID, ie the new one with new security.

Dan


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