Why does this repair action work?

Hi All,

Windows XP.

Problem: I have several road warriors. When they get back from their trailer parks or hotels, they can not browse websites on their wireless at their homes or offices.

Symptom: both Firefox and IE can not resolve an address. Ping and Nslookup can. If you copy and paste the IP address from Ping or Nslookup into Firefox or IE, both can open the IP's websites. Symptom happens with or without the antivirus/firewall enabled.

Solution: go into the device manager and disable the wireless card and re-enable it. Then, do a "repair" on their network connection. (A repair by itself does not work.)

Okay. Now I am confused. Why does this work? And what am I actually doing to fix the thing?

Many thanks,

-T

Reply to
Todd
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Try turning off the power management on the wireless card. If that works, then check if there's a more recent driver for that card available from the manufacturer. A number of network devices have had driver troubles related to power management. Some have better drivers, others don't, leaving only with the option to disable the power functions.

-Bill Kearney

Reply to
Bill Kearney

It's a feature, not a bug. If your laptops go into standby or hibernate mode, they retain the IP address, gateway, and DNS settings to that recovery is instantaneous. That's rather handy if the user falls asleep in front of the laptop, but does have some entertaining aspects when the laptop moves between going into standby/hibernate, and later recovering in a completely different IP environment. It's like you going to sleep and waking up in a different bed or room. Confusion is inevitable in both cases.

Most wireless clients will recognize that there's a problem when they try to renew the DHCP lease. Unfortunately, Windoze Wireless Zero Config is not one of those. Therefore, you might need to give Microsoft a little help. Doing the repair ordeal forces a DHCP renewal, which is why it works. However, it's rather tedious. Instead, I suggest:

Start -> run -> cmd ipconfig /release (wait about 3-5 seconds>

ipconfig /renew exit

That forces a DHCP renewal, which should help.

There are other settings which also need to be tweaked for different locations. For example, available printers, static routes, SMTP servers, Windoze domain, time zone(?), etc. I use Netswitcher to accomplish these changes. $20. I have one profile setup for each of my major customers so that I don't have to fumble with changing settings when I arrive with my laptop.

Reply to
Jeff Liebermann

Macs have a "Locations" feature built in. It's a bit hard to set up (or understand, I guess) but once it's working, it's okay. You generally have to click the "renew dhcp lease" button when you change location from wireless to wired. What I'd like is to change automatically when it senses the Ethernet cable unplugged/plugged.

Reply to
Warren Oates

It's not that horrible under OS/X:

However, neither the PC or Mac versions work reliably with complexicated configurations such as VPN's and multi-homed configurations. Automatically switching outgoing SMTP mail servers is another features that Locations misses in both the PC and Mac. Vista makes a half-hearted attempt to get it right, but only offers 3 locations (Home, Office, Public) which does me no good. For a while, I was using .REG files, pre-configured to a specific location, and run when appropriate. That worked, but usually required a reboot.

802.11r (fast roaming) might fix the problem, but then every access point would have to be replaced or upgraded. That's not going to happen among my cheap customers.

Switching between wired and wireless interfaces is handled by Windoze at the IP level. No need to sense a connect or disconnect as the route metrics take care of the packet routing priority issues.

This works well for switching between ethernet and wireless as a fixed location, but fails miserably to detect the change when the location changes after a standby or hibernate.

I've often wanted to build a GPS into my laptop, which detects my location, and feeds the correct registry values to the registry or NetSwitcher. Laziness is a great motivator.

Mac OS X: How To Force a DHCP Lease Renewal

Yuck.

I suppose I could write a bash shell script for OS/X to do something like that. The problem is that I'm a lousy programmist and don't know how to detect if the cable is plugged/unplugged. Running: ifconfig eth0 shows UP and DOWN, but does not indicate if anything is unplugged. Also running: ipconfig set eth0 dhcp doesn't seem to force a DHCP release and renewal. Oh well. Another project I don't need (or have time to do).

Reply to
Jeff Liebermann

Memory fault. I forgot that John Navas wrote a VBS script to do the same thing more gracefully. See:

Reply to
Jeff Liebermann

Should the interface not be en0 ?

Reply to
LR

I should keep my bookmarks the same for all systems.

sudo ipconfig set en0 DHCP

From:-

formatting link
I think the wireless interface is probably en1 .

Reply to
LR

Tried this several times. It does not work. The symptom is that command line utilities (nslookup, ping) can resolve IP addresses but Windows programs (Firefox, IE) can not.

Reboots do not work either.

-T

Reply to
Todd

Weird. I have a few more guesses.

First, try clearing the DNS cache. ping and nslookup may be using the resolver cache instead of doing a new lookup. Run: ipconfig /flushdns and try ping etc. again.

Firefox and IE7 have an irritating habit of going offline at inconvenient times. For IE6 and IE7, see: File -> Work Offline For Firefox 2.0.17 and 3.0.3, the "Work Offline" is in the same location. Make sure the "Work OFfline" is *NOT* checked.

If that doesn't do the trick, it would be interesting to see if the network setting are changing. I've seen DHCP pickup a new IP address, but screwup on getting a new Gateway IP. Once, I had an XP box that refused to get DNS server addresses, but everything else will work. So try: start -> run -> cmd md \\junk cd \\junk ipconfig /all > before.txt Then, do the repair ritual followed by: ipconfig /all > after.txt

Now, compare before.txt with after.txt using fc (file compare): fc before.txt after.txt

Reply to
Jeff Liebermann

Now this seems to be very promising. I will be out at another customer with this problem this week. I will try this first before using the device manager.

Thank you!

-T

Reply to
Todd

On Sat, 08 Nov 2008 18:48:16 -0800, Todd wrote in :

What is the _exact_ error message from Firefox?

Do you have any proxy settings configured? Are DNS servers set to configure by DHCP or configured manually? Have you checked the DNS server settings when this failure occurs? Are they changing or not?

Reply to
John Navas

address not found

no

no

Symptom: windows programs can not resolve addresses; command line programs are able to. Disabling and reenabling the wireless card in device manager cures the problem.

The original question was, why does this work?

My guess was that Jeff had it correct: flush the dns. I am waiting for another instance of the problem to test Jeff's theory.

-T

Reply to
Todd

On Thu, 13 Nov 2008 11:46:20 -0800, Todd wrote in :

Then DNS is failing.

You checked? Not auto?

The IP numbers are exactly the same? Can you ping them? Did you run DNS diagnostics (like NSLOOKUP)?

Sorry, but that doesn't parse. AFAIK you've only tried 2 Windows programs that are quite similar. Have you tried something like Sam Spade?

Perhaps by flushing the DNS cache. Have you tried manually flushing the cache?

Why does what work?

I doubt that caching is the issue unless something else is broken.

Reply to
John Navas

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