Alastair.com.au

Every now and again I set up a Linux server for some reason (DNS, nagios, web, etc). My choice for distribution is CentOS, mainly due to the fact I just like RedHat based distros.

There are usually a number of actions I perform on every server and I thought I’d collate them here so I don’t have to go looking around the web each time I need to remember the sequence of commands I need to run. There won’t be much here to start with but over time I hope this will build into a decent resource.

Disable IPv6

From: http://wiki.centos.org/FAQ/CentOS5#head-47912ebdae3b5ac10ff76053ef057c366b421dc4

Nothing I’ve done so far requires IPv6 so I disable it as having to sort through lists of IPv6 addresses as well as IPv4 ones can be confusing.

Just a quick one: When installing Exchange 2010 on Server 2008 R2 you need to make sure the IIS 6 Compatibility features of the Web Server role are installed. Otherwise during Exchange 2010 setup you will get errors indicating it can’t access the IIS Metabase and/or Default website even though it’s functioning perfectly.

There are plenty of blogs and articles out there about setting up nagios and not quite as many covering distributed monitoring. However there isn’t much out there surrounding trouble shooting of nagios-nsca. I had been having a problem where it would only accept one request before it started failing. I went through all the possibilities including multiple configuration problems, file permissions (probably screwing a few things up there in the process) and account permission issues.

In the end it turned out to be a simple problem ostensibly caused by the SuSE guys (the Operating System I was working with).

In the default init script (under /etc/init.d/nsca) it had the following:

The line starting with the ‘#’ is the original. The -s option (the only difference) meant it start in “standalone single-process daemon” mode. From what I can tell means “only accept one response”, which is pretty useless. Changing it to daemon mode fixed all my problems, and ended about 3-4 days of hair-pulling stress.

Some helpful Nagios links:

• http://nagios.sourceforge.net/docs/2_0/distributed.html
• http://www.packtpub.com/article/passive-checks-nsca-nagios-service-check-acceptor
• http://www.mail-archive.com/nagios-users@lists.sourceforge.net/msg06776.html (this is the one that solved my problems).

In previous version of MS Word (going back a bit anyway), inserting a watermark meant you had to edit the page background directly, meaning you had to find the options to view the background, insert some text, go back to the document, etc. Microsoft Word 2010 makes the process a lot simpler. In the Ribbon under Page Layout there is a Watermark option with some default options and of course the ability to create your own.

I had added a new class to my project and for some reason Intellisense wasn’t working. It turns out that for some reason that file wasn’t set to compile as far as the project went. Once I had changed the Build Action to ‘Compile’, everything started behaving again.

Update: This was originally posted a few months ago before I got my hands on Windows 7, which has this functionality (and a bunch of other stuff) enabled by default.

I like my task bar a certain way. For example, I think it’s because I tend to restart my mail client (Outlook) less than my web browser (Firefox). As such I like having Outlook first in the taskbar, with Firefox 2nd (followed by my VNC/RDP management app, then other miscellaneous programs…).

Sometimes however Outlook has a funny habit, not of crashing, but just of restarting, or somehow moving it’s icon to the end of the taskbar queue. This is frustrating as I like to be lazy efficient with my time and knowing where things are going to be helps.

Usually the solution to this was to close down all the apps I had open, then reopen them in the correct order. When Outlook’s being as slow as the current economic situation this can take quite a while.

This morning I stumbled across a piece of software that’s simply amazing.. it just works and makes life so much simpler. The software is called Taskbar Shuffle (http://www.freewebs.com/nerdcave/taskbarshuffle.htm). It gives you the ability to a drag-and-drop taskbar icons into the right position. Seeing as there’s no other dragging and dropping going on in the taskbar area I don’t see why this hasn’t been done before.

Normally, Firefox won’t ask to remember passwords on HTTPS pages (such as Internet banking). If you’ve got a large number of accounts and passwords it can be frustrating which username and password goes with which site. This can be made more difficult by the fact banks in particular have increased security measures due to the financial natures of their businesses.

There is a way to get around this:

1. Locate nsLoginManager.js. For Windows computers this will generally be in C:Program FilesMozilla Firefoxcomponents (or C:Program Files (x86)… in the case of a 64-bit version of Windows).
2. Look for the _isAutocompleteDisabled function. On my computer it was located on line 724.
3. Replace the contents of the function (the part between the ‘{‘ and ‘}’ brackets with return false.
4. Restart Firefox

Disclaimers:

1. This is based around a Windows installation of Firefox. It should work the same for Linux and Mac OS X, but you’ll just need to find the location of nsLoginManager.js depending on your distribution.
2. Obviously you’ll have to take your security needs into consideration when doing this. If you can more about security than efficiency you might not want to do this.
3. As the file edited is part of the Firefox installation (rather than your Firefox profile) the chances are it will get overwritten with a new version of Firefox, or if you decide to reinstall. This means you’ll have to re-edit the file again.

A short list of some of my favourite free applications and software (in no particular order):

• CCleaner
  • http://www.ccleaner.com
  • Gets rid of unnecessary files and registry keys.
• Spybot Search & Destroy
  • http://www.safer-networking.org/en/home/index.html
  • Keeps your computer pretty free from malware.
• Digsby
  • http://www.digsby.com
  • All-in-one IM/Email Checking/Social Networking client.
• Process Explorer
  • http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
  • A task manager for Windows that’s so good Microsoft bought the company.
• 7-zip
  • http://7-zip.org/
  • Not the prettiest compression manager but it does a great job.
• VLC
  • http://www.videolan.org
  • All-powerful multi-media player. Again, not as good looking as WMP or iTunes, but does the job and is cross platform so you can use it in Windows, Linux or Mac.

Most malware doesn’t want to be found. Hiding executables, programs that re-create startup Reg Keys.. some are nastier than others.