Showing posts from March, 2008

Nagios & NagVis

Found an add-on for Nagios, the well-known open source monitoring tool based on SNMP. NagViz adds visualization to Nagios, in a way that - as far as I understand it - lets you create a kind of dashboards to show everything is up. For instance, all devices related to Email delivery or a web application farm or your extranet portal.
Should help convince board members that Nagios is worthwhile as well as providing people with easy to use screens. Check out

Enable Linux Login Logout Scripts

Sometimes you need a logout script to do some housekeeping, such as clean up after processes or users... Some Linux shells have means for this, such as /bin/csh. Bash shell has a .bash_logout. But you may need something stronger.
Blogger Digest showed a neat trick to Enable Linux Login Logout Scripts to use a specific script of your choice. Great! Thanks!

SAMBA: Failed to verify incoming ticket

Solved an obscure error for some Windows 2003 R2 servers that were unable to map a drive to a SAMBA share. SAMBA is running on Oracle Enterprise Linux 4U6 with configs as defined by a wiki over at SAMBA. Error logs showed repeated "Failed to verify incoming ticket" errors.

Problem turned out to be related to Kerberos. Not so much the version or the encryption (MIT vs. Heimdal), as many sources mention, but to plain and simple time keeping! The Windows servers giving the errors were VMs running on ESX hosts. VMware Tools is supposed to do the time keeping and time sync the VMs to ESX, however that had slipped a bit too much. Kerberos accepts a maximum of 5 minutes. Ours was 9 minutes off...

Creating a custom boot and splash image

While researching ways to create a custom boot image, so I can provision new systems automatically with a CD or a mounted ISO image, I also learned how to create a custom splash.lss image.

Most web pages out there instruct you to install ancient, obscure giftoppm tools - which you may not have or know how to get. I found out Irfanview (for Windows) easily lets you open and edit JPG or GIF images, rework them, add logos and text and save the result as a PPM file.
Then just scp the .ppm file to Linux and use the ppmtolss16 tool (obtained through 'yum install syslinux') to convert the PPM file to LSS. Build the custom ISO image and you're done!

Getting Started with Sed

We're trying to consolidate some scripts into one bigger script, but now you have to structure things a bit more. So I'm diving head-first into command-line replacement with sed. Needless to say I needed a Getting Started with Sed manual of some kind...
BTW, there is also an excellent book on Sed and Awk