Date: Wed, 8 Feb 2006 16:31:04 -0500
From: Robert Cahn < robertscahn@xxxxxxxxx>
Subject: Getting a new wireless IP link without rebooting.
To: fedora-list@xxxxxxxxxx
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< 5f7024460602081331u6f85b6a6me2334ff203093432@xxxxxxxxxxxxxx>
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I have a FC4 desktop. Every once and a while the 802.11 link fails in the
sense that DNS stops working. I have tried to inactivate the link and bring
it up again but when I do so I get "Determining IP information for eth0...
failed; no link present. Check cable?" Eventually I give up and reboot.
Is there anything else I do that is less disruptive and will restore
communication?
Bob Cahn
Gipsy Trail Club
Carmel, NY
RobertSCahn@xxxxxxxxx
If "Determining IP information for eth0" failed (assuming that eth0 is your wireless 802.11x link) then perhaps the link has gone down, or perhaps it is trying to attach to another AP.
Probably a good time to open a terminal (Applications > System Tools > Terminal) and then type:
su
Which will (after you apply the root password) make you the root user - then type:
/sbin/ifconfig
Which will show a lot of information about your networking. You should look to see that your wireless device is attached to an IP (like 192.168.0.3 for example). Also type:
/sbin/iwconfig
Which will show much information about your wireless link. Look for proper ESSID (name of your Access Point - the name assigned to your wireless modem probably) and take a good look at signal levels and any errors that are counted. If there is a problem where interference or faulty hardware is causing the link to become unstable it may show here.
If you find a good IP for your wireless device, and if the wireless info and ESSID also look good then try:
ping 192.168.0.1
Assuming that your modem's IP address is indeed 192.168.0.1. It's replys every second (you stop this with a ctl-c (hold down the Ctrl key and tap c)) tell you soon if you have a connection with your modem. If you do, then look at /etc/resolv.conf by:
cat /etc/resolv.conf
Those designated as dns servers will probably include your modem. This is a long shot but if all has been good to this point and if there are at least two dns servers in reslov.conf comment out the one with your modem's IP - close your browser and re-open and see if you have good browsing. I actually had a problem with a modem which would not reslove IPv6-dns. Best solution (easiest anyway) was to eliminate the DNS calls to it by taking it out of /etc/reslov.conf.
If you find that the wireless link is showing errors, try changing the wireless channel used or moving the access point (probably your modem) closer to your computer. Someone may have lit up wireless near you on the same channel perhaps.
All of the above commands can be used at any time and would be good to run to establish your working baseline.
Good Hunting!
Tod
