DHCP timeout for WPA-encrypted WLAN network

Wolfgang Jeltsch 4cqncnl7 at acme.softbase.org
Thu Sep 10 20:12:52 UTC 2009


Hello,

I try to access WLANs with the network applet of Kubuntu. Accessing 
unencrypted networks works fine. However, I’m not able to connect to my home 
network, which uses WPA encryption. My Kubuntu machine doesn’t get an answer 
from the DHCP server within 45 seconds, and after these 45 seconds, Network 
Manager kills the DHCP client. The relevant parts from /var/log/syslog are as 
follows:

    […] NetworkManager: <info>  Activation (wlan0) Beginning DHCP transaction.
    […] dhclient: Internet Systems Consortium DHCP Client V3.1.1
    […] dhclient: Copyright 2004-2008 Internet Systems Consortium.
    […] dhclient: All rights reserved.
    […] dhclient: For info, please visit http://www.isc.org/sw/dhcp/
    […] dhclient:
    […] dhclient: wmaster0: unknown hardware address type 801
    […] dhclient: wmaster0: unknown hardware address type 801
    […] NetworkManager: <info>  dhclient started with pid 7120
    […] NetworkManager: <info>  Activation (wlan0) Stage 3 of 5 (IP Configure
    Start) complete.
    […] NetworkManager: <info>  DHCP: device wlan0 state changed normal exit
    -> preinit
    […] dhclient: Listening on LPF/wlan0/[…]
    […] dhclient: Sending on   LPF/wlan0/[…]
    […] dhclient: Sending on   Socket/fallback
    […] dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 6
    […] dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 10
    […] dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 14
    […] dhclient: DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 14
    […] NetworkManager: <info>  Device 'wlan0' DHCP transaction took too long
    (>45s), stopping it.
    […] NetworkManager: <info>  wlan0: canceled DHCP transaction, dhcp client
    pid 7120

So the point is that there are multiple DHCPDISCOVERs, but no answer. However, 
I have earlier experiences where a DHCP answer came only after a few 
DHCPDISCOVERs, probably after more than 45 seconds.

So I’d like to know whether there seems to be a fundamental problem here or 
whether the timeout is just too short. If the latter is the case, how can I 
increase it?

Best wishes,
Wolfgang




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