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March 2, 2022 – 2:00 pm

Books have been written on the subject of awk and sed. Here’s a small sample of commands I put together over the years that are useful for everyday system administration tasks. Most of these tasks …

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Article Archive for September 2014

Remove Duplicate IPTables Rules

September 24, 2014 – 6:26 pm

Duplicate entries may appear in your iptables configuration due to parallel efforts of various network security-related applications that may be running on your server. In most cases, having duplicate iptables rules is no big deal, …

Block WordPress Attackers With IPTables

September 23, 2014 – 3:56 pm
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After installing LogStash, I noticed server load went from around 1.2 to 50+. This was cause by a brute-force attack against WordPress wp-login.php from some IP in France (of all places). While LogStash should not …

Patching Binary Files in Bash

September 18, 2014 – 12:17 pm
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Just the other day I ran into a particularly annoying issue: after an application upgrade, all printed documents had “<<bbj>>~D” on the first line. The application sends EPS files to the CUPS print server. For whatever reason, …

CUPS Printing to a File

September 17, 2014 – 7:17 pm
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Using CUPS to print to a file instead of an actual printer is a great idea for troubleshooting and archiving purposes. This saves trees but, most importantly, saves you the walk to the printer. So, how …

PHP Unable to allocate memory for pool

September 9, 2014 – 10:57 pm
apache

The following error may be found in /var/log/httpd/${domain}/error_log when APC memory is set too low: “PHP Warning: require_once(): Unable to allocate memory for pool”. APC is Alternative PHP Cache. You can check the version of …

Getting Epoch Time on Solaris 10 and Older

September 8, 2014 – 3:57 pm
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You can get the epoch time on Solaris 11 and Linux simply by running the date command: