Subject: Re: problem with WPA/802.11i and dhclient
To: Brett Lymn <firstname.lastname@example.org>
From: Steven M. Bellovin <email@example.com>
Date: 07/23/2007 09:07:30
On Mon, 23 Jul 2007 22:23:51 +0930
Brett Lymn <firstname.lastname@example.org> wrote:
> I have just changed my wireless network over from using WEP to WPA. I
> have managed to get the WPA working ok, I have network connectivity
> now apart from one issue but I seem to have worked around that.
> The problem that does have me stumped is getting a DHCP address. When
> I was using WEP I could get a DHCP address from my server without an
> issue but with WPA it never succeeds - it looks like dhclient(8) does
> not allow enough time for the WPA negotiation to finish after it
> brings the wireless interface up before it decides to send a packet
> and then gives up on the whole process due to getting no replies. I
> have looked at the protocol timings in dhclient.conf(5) but none of
> them seem to be what I want.
> Needless to say, if I manually configure the network it works fine but
> I would really rather not do this - I have set up some special bits in
> dhcp which means I don't have to do special scripts on the laptop when
> I am at home.
dhclient has many problems with links that take a while to come up;
I've complained about this in the past.
One technique that sometimes works is to remove all media lines from
dhclient.conf; specify the appropriate values manually.
As for options -- I suspect that a combination of initial-interval and
backoff-cutoff will increase the delays; however, I haven't tried it.
--Steve Bellovin, http://www.cs.columbia.edu/~smb