Wireless Network Troubleshooting

Be sure to check this section first. We'll post the most recent issues affecting wireless connectivity here.


Roaming

Issue: If you use wireless in one location, put your laptop into "Sleep" mode, and move to another location, you may experience difficulty connecting to wireless in the new location. The reason for this is that the computer "remembers" the previous location and tries to restore it. Since that location is now out of range, the connection fails. The Macintosh appears particularly prone to this behavior.

Solution: The way to restore connectivity is to connect to a different Caltech wireless network than you were previously on. For example, if you were using BeaverNet, connect to either Guest or Registered (assuming you've registered your wireless MAC address). That will force your computer to connect from the new location. You can then reconnect to your desired network.


Bluetooth Interference

Issue: If you are having trouble connecting to a Caltech wireless network, check to see if your Bluetooth connection is active. Wireless networking and Bluetooth both use the same radio frequency and can interfere with each other.

Solution: Try turning off Bluetooth and see if wireless connectivity improves.


Ubuntu Broadcom Wireless Card

Issue: There is a known issue with Ubuntu and certain Broadcom wireless cards causing computer freezes when accessing BeaverNet. The symptoms are that the computer stops responding to keyboard/mouse events and the caps lock and num lock lights may or may not be flashing.

Solution: Restarting the computer restores normal operation. The wireless card can be identified by executing lscpi in a terminal window. If the command fails you may need to execute whereis lspci to get the full path for the command. You'll get around 20 or so lines of output. If you have the affected Broadcom card there will be a line that looks something like this:

0c:00.0 Network controller: Broadcom Corporation BCM4328 802.11a/b/g/n (rev 03)

The model identifier (e.g. BCM4328) may have slightly different numbers, but will be in the form BCM43xx. Dell computers may have this card (Dell's model is 139x).

This issue only affects connections to BeaverNet. The card can connect to Guest and Registered networks normally. At this time we cannot recommend any workarounds. We are researching solutions and will update this page as we learn more.


Firefox Connection Delay

Issue: When connected to the Caltech Guest wireless network, users accessing web pages with Firefox 3 may experience an initial 10-second delay before they are redirected to the Guest Welcome page, prompting some users to mistakenly believe that there is a wireless connection failure. This delay is due to the Online Certificate Status Protocol (OCSP) feature being enabled by default under Firefox 3. Under Firefox 2, as well as with other web browsers such as Internet Explorer and Safari, OCSP is disabled by default. When OCSP is disabled, the Guest Welcome page appears immediately when a user initially tries to access any web page.

Solution: To disable OCSP under Firefox 3, follow these steps.

  1. Click on Tools -> Options -> Advanced option -> Encryption tab -> Validation button.
  2. Uncheck the top box so that OCSP will not be used to confirm the validity of certificates.
  3. Click on the OK buttons to close all of the Options windows.

For more information on OCSP, please see this link at Mozilla.
If you are still experiencing problems using the Guest network, contact us at http://help.caltech.edu (request type IMSS-->Network, Wireless & Remote Access-->Cannot connect to-->Wireless). Be sure to include your operating system and browser versions.


General Suggestions for BeaverNet Connections

Here are a few suggestions in general for users having trouble connecting to BeaverNet:

  1. Please review the Requirements and Recomendations page to see if your hardware is compatible.Your computer and operating system must at least meet these requirements to connect to BeaverNet.
  2. Be sure that your computer is fully up to date on operating system upgrades and patches.
    Note: There are recent security updates for Mac OS that may improve BeaverNet connections. Please see http://support.apple.com/kb/HT1222for more information.
  3. Install the latest driver for your wireless card.
  4. Be sure that you have followed the installation instructions carefully.
  5. It is necessary to use WPA2 Enterprise when connecting to BeaverNet. Your operating system may have support for other types of WPA2 connections but these will not work. In one case, a Mac with Leopard WPA2 could be selected, but when the user attempted to connect, the operating system chose a different method and failed.
  6. If your login fails, check to see that you are using the correct password. Log into https://utils.its.caltech.edu/. If your login is successful then your password is correct. Once logged in, if you see a message like this:

    Warning! Your IMSS Unix and Windows passwords have become unsynchronized somehow. Please log out and log back in using your Windows password, and both passwords will be set to that password.

    then follow the instructions to resynchronize your Windows and Unix passwords.
  7. Check to see if your operating system has more than one utility to manage your wireless connection. For example, Dell provides a wireless connection utility that can conflict with the built-in Windows utility. See below for instructions to resolve the conflict.
  8. If you have previously associated with a non-IMSS wireless network, you may want to disable automatic association for that network so that it doesn't take priority over your IMSS wireless network connection.

BeaverNet Authentication Problems with Windows XP

Authentication problems with Windows XP and BeaverNet may be due to the operating system caching user credentials. The indication is that when the user is prompted to enter credentials, the domain and username fields are greyed out, with only the password field being editable. The Registry key containing the credentials is at:

HKEY_CURRENT_USER\\Software\\Microsoft\\Eapol\\UserEapInfo

Complete instructions for removing the cached credentials are available at:

http://support.microsoft.com/kb/823731

You can also use the command line and issue the following command:

reg delete HKCU\\Software\\Microsoft\\EAPOL\\UserEapInfo /f

Note: Modifying the Windows Registry incorrectly can cause serious problems with your operating system. Be sure to follow the instructions carefully.If your system has multiple utilities for managing wireless connections, they may be conflicting with each other. To resolve the conflict you'll need to tell the utility you don't want to use to stop managing connections. The Dell utility can be disabled by removing the check from the "Let this tool manage your wireless networks" field. If you have another untility consult its documentation.


Wireless Connectivity Issues with Macintosh OSX Leopard

There have been reports of users of Mac OSX Leopard having trouble connecting to wireless networks using WPA2 encryption, which is what the Caltech BeaverNet uses. The reports aren't very consistent; some users connect effortlessly, while others can't connect at all, or repeatedly connect and then lose the connection. Caltech users have experienced this, and Apple's web forums have many complaints with the same indications. So far there haven't been any clear answers to the problems. We are working to find answers to these issues, and will be updating this page as we learn more.

Solution Suggestions: Here are some suggestions to try if you are having trouble connecting to BeaverNet with Leopard:

  1. Check to see what version of Leopard you are running. The current version is 10.5.2.
  2. There are reports that laptops running on battery power repeatedly connect and then lose connection. This can also occur if the laptop goes to sleep. Plug the laptop into the AC adapter, and set the computer to never sleep, and uncheck the Put the hard disk to sleep option. Granted, this is not very compatible with the idea of a laptop in the first place, but it may help to identify where the problem(s) are.
  3. OSX is very good at storing information so that you don't have to reenter it all the time. You may want to clear any retained information from previous login attempts and create a new login. To clear a wireless network configuration from OSX:
  4. Launch System Preferences, and choose the Network pane.,
  5. In the left column of the Network pane, click on the Aiport item to select it.
  6. Click on the Advanced button in the Network pane. If OSX has stored a configuration for BeaverNet, you'll see it in the Preferred Networks field.
  7. Click on the BeaverNet entry to highlight it. Then, click on the minus sign button to remove the BeaverNet entry. Also, click on the Remember any network this computer has joined to unselect it. Then click on OK. You'll return to the Network pane.
  8. The Apply button in the Network panel will be active (i.e. not greyed out). Click on it to apply the change.
  9. You may also want to clear the credentials that BeaverNet uses from the Apple Keychain. To do this, launch the Keychain Access applet from the Utilties section under Applications. In Keychain Access, there are 2 entries that the BeaverNet wireless configuration uses. One is named win-radius-srv1.ad.caltech.edu, which is the security certificate used to provide encryption. The other is named WPA: Caltech Beavernet, which is your IMSS user credentials used for authentication.
  10. If you don't see these entries, then the computer has not stored this information. You can quit the Keychain applet and create a new configuration.
  11. To delete the entries do the following:
    • Click on the entry to highlight it. Be sure to select only the item you want to delete.
    • From the Edit menu, choose the Delete item. The Delete item will not be highlighted if no entry is selected. You'll be asked to confirm your choice. Be careful as changes to the Keychain are immediate.
    • Warning: Under the File menu, there is a Delete Keychain item. This is not what you want. Be sure to use the Edit Menu->Delete item to remove a key chain entry.
  12. Once you have removed the entries, you can quit the Keychain Access applet and follow the instructions to create a new BeaverNet configuration.