Monthly Archives: June 2007

Upgrading the miniPCI wireless card in a Thinkpad X31

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A few years ago when I first bought it, I installed a Lucent Technologies Prism based mini-pci wifi card in my IBM/Lenovo Thinkpad X31 laptop because the prism chipset had good linux support.  But, it does not support WPA2 encryption. I decided the easiest fix was to upgrade to an Intel Pro/Wireless 2100 Lan adapter, which is now supported and works with the wpa_supplicant program to support WPA2 encryption.

The only problem I ran into durring the procedure was that my laptop BIOS had a "whitelist" of approved cards (those sold by IBM) and when I booted it after installing the new card a warning message came up as follows:

ERROR

1802: Unauthorized network card is plugged in – Power off and remove the miniPCI network card.

and, the laptop wouldn't boot. (I just LOVE vendor lock in….)

Luckily, somebody had already figured out how to disable the BIOS whitelist and I found the following program in the Linux Kernel Mailing List archive here: http://lkml.org/lkml/2004/6/13/69

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Finding hosts in new known_hosts files which are hashed

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Older versions of SSH kept a ~/.ssh/known_hosts file which contained the name of each server you had connected to, along with it's public key. If you ever wanted to erase a public key, you simply edited the file with your favorite text editor, found the name of the server, and then deleted that line. (You might do this for example if the server admin had changed the public key of the server, and you wanted to tell SSH that it was ok to grab the new key and use it instead of the old key.)

 New versions of SSH store the server name in a hashed form, so you can't visually identify it (it's not human readable). This is a security feature so that somebody with access to you known_hosts file can't figure out what other machines you have connected to (and that they should try to hack next, etc). But it makes your job harder when you want to delete a single host's key.

The inelegant solution is to just delete the whole file and then accept new keys from everybody, but this is a security risk. To find out which hashed entry matches the server whose key you are trying to replace, simply run the following command:

ssh-keygen -F servername.com
 

Or, even better, to simply remove the server from your known_hosts file all in one command, use:

ssh-keygen -R servername.com

Adding custom headers (such as Approved:) to Thunderbird mail

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Sometimes you want to send email or newsgroup posts with custom headers. For example, the Approved: header can be used to post to a restricted "Announce" newsgroup for a class, or you may want to mark your email with an "X-No-Arc: yes" header to prevent a mailing list archive from saving a copy. 

The easy way to add a custom header to the Thunderbird email/newsgroup compose window is by adding a user.js file to your configuration directory ( .thunderbird/default//user.js ) with the following line in it:

user_pref("mail.compose.other.header", "Approved");