Dax's Blog

VMware Workstation 8 and VMware Player 4 only support kernels up to 3.0. Any later requires patching of the VMware modules.

Patch for VMware Workstation 8.0.1

vmware8.0.1linux32fix.tar.gz

Patch for VMware Workstation 8.0.2

vmware8.0.2linux32fix.tar.gz


$ cd /tmp
$ wget tarball_from_above
$ tar xvf vmware8*linux32fix.tar.gz
$ cd 3.2/
$ sudo ./patch-modules.sh


The RHEL6.1 beta was released today. At Guru Labs we have to stay on top of the latest changes so that our Linux training has full coverage. I read the release notes and the following items stood out to me.

• New biosdevname style network interface names on some new Dell servers. Disabled by default everywhere else (for now).
• Control Groups updated with the "autogroup" feature and I/O throttling.
• The crashkernel=auto parameter syntax is removed. The default parameter syntax is now crashkernel=:[@offset].
• New kernel message dumper for easier kernel panic analysis
• Support for the embedded graphics/GPU in the new Intel Sandy Bridge CPUs
• Being able to take a snapshot of a mirrored logical volume is fully supported
• Now possible to combine RAID0 (striping) and RAID1 (mirroring) in a single logical volume in LVM
• Improved support for iSCSI adapters at installation and boot time, including the ability to separate login credentials for iSCSI (A feature I requested when I added iSCSI coverage to our training materials and noticed the deficiency)
• Lots of KVM/QEMU updates
• Btrfs is a technology preview (x86_64 only)
• Lots of new "technology previews" added

If you have a RHEL6 box which ships both Apache and Tomcat6 you might want to connect the two together. You probably have looked around for mod_jk as a RHEL6 RPM or SRPM (src.rpm).

You find that It isn't in EPEL, and it isn't in Red Hat Optional Server 6 RHN channel, etc.

It seems that the new way forward with RHEL/Fedora world is to use mod_proxy_ajp. For example, the RH/Fedora project Spacewalk switched from mod_jk to mod_proxy_ajp.

Note that mod_proxy_ajp is a core module of Apache 2.2 and newer so this should be a rather definitive/final change in recommended connector for Tomcat and Apache.

Read the docs, but to get you started in configuration first you'll want to configure Tomcat's conf/server.xml file to have something like (which may already exist):

<Connector port="8009" enableLookups="false" redirectPort="8443" protocol="AJP/1.3" />

And Apache with something like:

<Proxy *>
 AddDefaultCharset Off
 Order deny,allow
 Allow from all
</Proxy>

ProxyPass / ajp://localhost:8009/
ProxyPassReverse / ajp://localhost:8009/

For about 10 years, I lived only about 3 miles from my office. Since moving into my new home, I have about a 35-40 minute commute. This has given me the opportunity to listen to audio that I didn't have before. I don't mind listening to music, and I enjoy it, but given the choice I'd rather listen to something educational and interesting.

Recently I discovered This American Life which I has been amazing. The episodes come out once a week, and I eagerly wait for the next one to be released.

They have a rather large archive of back shows since it has been airing since 1995. On their website you can listen to the MP3s of the archive, or you can purchase them on iTunes or Amazon.

They have a "short list" of recommended shows from their archive, and also "other favorites".

I figured out the light weight obfuscation used to conceal the URLs to the MP3s, and came up with the following to download the "short list" and the "other favorites":

SHORT LIST:

U=http://audio.thisamericanlife.org/jomamashouse/ismymamashouse/
for i in 109 175 206 218 241 355 360 396
> do
> wget $U$i.mp3
> done

OTHER FAVORITES:

U=http://audio.thisamericanlife.org/jomamashouse/ismymamashouse/
for i in 27 38 46 61 77 84 88 90 103 118 119 154 164 178 181 186 192 199 203 204 220 233 246 248 252 253 268 275 282 290 299 304 322 339 352 361 381 388 403 405 427
> do
> wget $U$i.mp3
> done

If you elect to use my technique, please Donate to This American Life.

SUSE has long used YaST as a management tool. It makes it easy to make changes to your system without knowing (or caring) what happens behind the scenes.

At Guru Labs, our Linux Training is all about teaching students what happens "behind the scenes". We strive to document the official and best practice techniques (not always the same thing, unfortunately).

Recently we were updating our courseware and wanted to document how to disable IPv6 in the various Enterprise Linux distributions. The question came up, "What does YaST actually do when you toggle the Enable/Disable IPv6 checkbox in the YaST network module." To answer that question I performed the following steps on SLES11.

Search for the string IPv6 in the YaST network module.

grep -n IPv6 $(rpm -ql yast2-network)

In the output, found these lines looked interesting (Note the Disable/Enable strings)

/usr/share/YaST2/modules/Lan.ycp:316:global void SetIPv6(boolean status){
/usr/share/YaST2/modules/Lan.ycp:324:void writeIPv6(){
/usr/share/YaST2/modules/Lan.ycp:424: writeIPv6();
/usr/share/YaST2/modules/Lan.ycp:654: status_v6 = _("Support for IPv6 protocol is enabled");
/usr/share/YaST2/modules/Lan.ycp:656: link_v6 = Hyperlink (href_v6, _("Disable IPv6"));
/usr/share/YaST2/modules/Lan.ycp:662: status_v6 = _("Support for IPv6 protocol is disabled");
/usr/share/YaST2/modules/Lan.ycp:664: link_v6 = Hyperlink (href_v6, _("Enable IPv6"));

Based on my experience I guessed that the writeIPv6 function does the work of enabling and disabling IPv6 on the system.

So I took a look at that function using the line number found by grep:

vim /usr/share/YaST2/modules/Lan.ycp +324

I found the following:

void writeIPv6(){
SCR::Write(.target.string, "/etc/modprobe.d/ipv6", sformat("%1install ipv6 /bin/true", ipv6?"#":""));
SCR::Write(.sysconfig.windowmanager.KDE_USE_IPV6, ipv6?"yes":"no");
}

That pointed me at the two files "/etc/modprobe.d/ipv6" and "/etc/sysconfig/windowmanger".

Looking at the files it seems YaST simply removes/adds the comment character in front of the one-and-only line in the file /etc/modprobe.d/ipv6 and it toggles the variable KDE_USE_IPV6 in /etc/sysconfg/windowmanager.

If you ever have the need to discover what YaST is doing behind the scenes, you can use the same technique.