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Archive for the ‘System Administration’ Category

El Capitan Leads to More DNS Woes

For whatever reason, Apple really likes messing with how I use DNS. I've written many, many, many times about having to modify OS X's DNS functionality to append search domains when a hostname includes a dot. Every single time I upgrade, this change is broken.

Categories: System Administration

nginx: Blocking Access to /xmlrpc.php

I recently ran into an issue on a WordPress site running behind an nginx web server. The site was frequently being attacked by a botnet hitting /xmlrpc.php so rapidly, it would eventually force the FastCGI processes behind nginx to consume all available CPU. Naturally, this would cause all legitimate traffic to the site to timeout. […]

Categories: System Administration

Goodbye, discoveryd. Hello again, mDNSResponder.

Great! Once again, Apple has made a change in how DNS is handled in Mac OS X. Originally, Yosemite (10.10) had replaced mDNSResponder with discoveryd. This meant that all of those who had made a change to force mDNSResponder to always append search domains to DNS lookups had to make a new change to accommodate […]

Categories: System Administration

Why Isn't tmpreaper Working?

If you have a directory that you want to keep clean, tmpreaper is a great way to remove files based on how old they are. The other day, I had a directory that looked like this: x@x:~/dump$ ls -l -rw-r--r-- 1 x x 212268169 Mar 15 01:02 x-2015-03-15.sql.gz -rw-r--r-- 1 x x 212270156 Mar 16 […]

Categories: System Administration

WARNING: The following packages cannot be authenticated!

We run several (read: hundreds) of servers that are still running Debian 6 (Squeeze). A few months ago, we started seeing the following errors coming from the daily apt cronjob: 'WARNING: The following packages cannot be authenticated!'

Categories: System Administration