March 2011

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Getting More out of the Nagios Statusmap

March 27, 2011 in Nagios | 3 comments

The Nagios Statusmap is one of those features that gets a lot of attention when you first set up your monitoring server, but when looking back after a while most people notice that they don’t really use it at all.

When it comes to daily monitoring I never found it very useful, either, but it has always served one important purpose for me: when adding new hosts or networks the Statusmap reveals whether I got all my parent/child relationships right. And since I work in a dynamic and growing environment I add a lot of hosts on a regular basis.

There is one thing that always annoyed me when looking at the Statusmap: when you exclude certain host groups from the map, only the host icons for those hosts get removed, but the map still shows their status in green or red, and with over a hundred hosts it’s still very hard to identify individual hosts.

Today I stumbled across a patch for the Statusmap on the Nagios Exchange that addresses this very issue. It really excludes the hosts from the map, i.e. it is re-drawn as if the excluded hosts just didn’t exist.

Here’s an example:

original Statusmap (before the update)

improved Statusmap (after the update)

If you would like to update your Nagios install, proceed as follows. I’m assuming that you have built Nagios yourself. I have tested this with the most recent version of Nagios 3.2.3

Before you begin, cd to the cgi folder inside your Nagios source download folder, e.g. ~/downloads/nagios-3.2.3/cgi

curl "http://exchange.nagios.org/components/com_mtree/attachment.php?link_id=1807&cf_id=24" > statusmap.diff
patch statusmap.c statusmap.diff
make statusmap.cgi
cp statusmap.cgi /usr/local/nagios/sbin/
cd /usr/local/nagios/sbin/
chmod g+w statusmap.cgi
chown nagios:nagios statusmap.cgi

Redirect Wildcard- or Sub-Domains to Main Site with Apache

March 18, 2011 in Apache | No comments

If you want to re-direct users from your subdomain(s) to your main site you can use a virtual host configuration like this:

<VirtualHost *:80>
  ServerName www.ten-fingers-and-a-brain.com
  ServerAlias *.ten-fingers-and-a-brain.com
  Redirect permanent / http://ten-fingers-and-a-brain.com/
</VirtualHost>

If you want to have the main site under the www name you should change the configuration like this:

<VirtualHost *:80>
  ServerName ten-fingers-and-a-brain.com
  ServerAlias *.ten-fingers-and-a-brain.com
  Redirect permanent / http://www.ten-fingers-and-a-brain.com/
</VirtualHost>

Please make sure that your main site comes before this one in the configuration, e.g. by placing it at the top of the same file.

You thought WordPress does this without additional configuration? Well, you’re generally right, but if you let WordPress do the work that’s one extra round of loading PHP and connecting to the database. My approach is much faster and causes less server load.

Why bother? For instance because Google or Bing will not see duplicate content, both under the main site and the www subdomain. Avoiding duplicate content has a positive effect on your ranking in search results.

bug in function wp_count_comments in wp-includes/comment.php (with patch for WordPress 3.1)

March 17, 2011 | No comments

WordPress plugin updated: Comment E-Mail Verification (0.4-beta)

March 8, 2011 in E-Mail, WordPress Plugins | No comments

The newest version (0.4-beta) of my Comment E-Mail Verification plugin now has an option to hold comments for moderation even after the authors have verified their E-mail addresses.

Download it directly from the wordpress.org plugin directory

This update was inspired by user comments. Thanks for all your input.

This is a beta version because the entire moderation/verification process requires some more streamlining and new default messages, but I felt there would be an audience for an early update anyway. If you have any suggestions or spotted an error: please share!