Intel releases updated Linux drivers

Intel has released a new version of the open source Intel graphics package, that can be used on Linux systems. This is good news for users of the software, who will be able to access the updated version, known as 12.07. With the package, users will get new X Server drivers for Intel cards, along with other features that work with these specific drivers.

Version 2.20.0 is the most significant component of this new release, available with the xf86-video-intel driver for the X Server. Those who regularly use this type of technology, or any for that matter, spending time on their computers playing poker.de or communicating to their friends via e-mail, will be glad to hear this news. The feature comes with SNA, which is a 2D acceleration method that can be selected at runtime. It’s purpose is to use less CPU than the previous method, UXA, and to be faster. To take advantage of this, the user must specify Option “AccelMethod” “sna” in the Xorg.conf file. It also features modern Intel graphics cards, which the new SNA architecture is designed to make the most of.

This new release from Intel is pre-tested, and therefore geared towards developers who look for this feature rather than Linux end users. It comes with other features that have also been tested, along with the main ones that will be the biggest draw. The other features include the stable 3.4.x version of the Linux kernel. This was made available to users in May and its default setting is to use the RC6 power saving mode. Those who want to get their hands on this new package can download it from Intel’s Linux driver web site and begin enjoying the benefits. Its source code is licensed under MIT and GPLv2 licences.

Posted in OS, System | Leave a comment



Microsoft’s Bigguns

In April Microsoft made news when it became a top-twenty contributor to the Linux kernel. The Redmond giant contributed over 20,000 lines of code in support of Hyper-V. This was a striking turn around. Remember, Microsoft’s CEO once described Linux as a “cancer.”

Although it contributed over twenty thousand lines of code, the Internets are now abuzz over a single line of code in hv/hv.h line 45:

  #define HV_LINUX_GUEST_ID_HI 0xB16B00B5

A Microsoft programmer assigned 0xB16B00B5 to HV_LINUX_GUEST_ID_HI. That’s a hexadecimal number whose value is 2,976,579,765. But that’s not what has the Internets all worked up. Look again. 0xB16B00B5 is 1337-speak for BIG BOOBS.

Posted in Programming | Leave a comment



SSH – Disable known_hosts Prompt

Do you have scripts that do remote procedures over ssh? Do host key checks occasionally cause them to break? This entry will show you how to avoid that mess and keep your scripts running smoothly.

BACKGROUND

ssh protocol is designed to verify the host key against a local file to ensure the integrity of the remote server. By default, the user is prompted to accept a new key or warned when the host key changes (like after a server upgrade). This is a nice defense against man-in-the-middle attacks, but it plays havoc on scripts. If a prompt occurs, your script stops and waits for input.

FIX

There are two ways you can avoid this problem. You can pass parameters to ssh or you can change the system setting in ssh_config. If you want to turn off host key checks for scripting continuity, then we recommend using command line parameters. You only type them once when you write your script and they only affect that instance of ssh.

By default, StrictHostKeyChecking is set to ‘ask.’ That’s why you’re prompted to accept a key. In order to avoid the prompt, you can change that to ‘no.’ When it’s set to ‘no’ the key is stored with no questions asked.

Unfortunatley, that’s not as clean as it seems. If the host signature changes due to an upgrade, then ssh stores that key, too. Since you have two, it starts throwing warnings such as this:

key_read: uudecode AAAAAAAB3NzaC1yc2EAAAABIwAAAQEAzh1G5NiiEfawhBhly
VLR92Q/+iXZ3Bs56RBLZtso/lEFk9TYZuS+Qp+tKOIv1j5HpuwsoIAZt6A1fJfCHfN3
KYtuWNbdMywuoOUb5Z9S0c/3jyeesy2eTy+ZZjgb0uPdU8cCKg029NF9gQr5tbDlrj+
vW6QvvWJ0KVJFJPWg6u3/Qt/N/xlPXziyHv4HKuzMDoRLQ5ltiC8zk3ZefeRK7ZZKtp
qSneTsHZt7alOGOsKTrPL5PA50QwBiNJFbvrnmJs2Xjk3x6MunXFuRSZCEsGboQWDie
whcOFxDlkYfWjHNbShPYBY3xuq/MnsL8QHUx9AT75wpl2U0/KFbXsMAKw==
 failed
key_read: uudecode AAAAAAAB3NzaC1yc2EAAAABIwAAAQEAzh1G5NiiEfawhBhly
VLR92Q/+iXZ3Bs56RBLZtso/lEFk9TYZuS+Qp+tKOIv1j5HpuwsoIAZt6A1fJfCHfN3
KYtuWNbdMywuoOUb5Z9S0c/3jyeesy2eTy+ZZjgb0uPdU8cCKg029NF9gQr5tbDlrj+
vW6QvvWJ0KVJFJPWg6u3/Qt/N/xlPXziyHv4HKuzMDoRLQ5ltiC8zk3ZefeRK7ZZKtp
qSneTsHZt7alOGOsKTrPL5PA50QwBiNJFbvrnmJs2Xjk3x6MunXFuRSZCEsGboQWDie
whcOFxDlkYfWjHNbShPYBY3xuq/MnsL8QHUx9AT75wpl2U0/KFbXsMAKw==
 failed
Last login: Fri Jul 13 11:09:36 2012 from jdfulmer-lt.joedog.org
RedHat 5Server - LinuxCOE 4.2 Fri May 11 09:48:33 EDT 2012

We can avoid this mess with another setting. Instead of saving host key entries to known_hosts, we can bury them in /dev/null. We can change the file location with the UserKnownHostsFile parameter. If we change it to /dev/null there are no entries for ssh to read.  And when it writes a new entry, well it goes to /dev/null

IMPLEMENTATION

There are two ways we can implement this. One is at the script level and the other is at the system level. If we want to continue to prompt for host key checks, then we can add the configuration to our script. This can be done with OpenSSH’s -o option. Here’s an example in which we run the hostname command on a remote server:

ssh -o StrictHostKeyChecking=no \
    -o UserKnownHostsFile=/dev/null \
       user@host /usr/bin/hostname -s

To set this configuration system-wide, place these entries in ssh_config:

StrictHostKeyChecking no 
UserKnownHostsFile /dev/null
LogLevel QUIET

NOTE: This configuration applies only to OUTBOUND ssh connections. This does not affect your system’s inbound ssh traffic.

UPDATE:  I added LogLevel  QUIET to the ssh_config above. This is the same as running ssh with a “-q”. This suppresses all warning messages which may wreak havoc on your scripts.

Posted in Applications, ssh | 1 Comment