Category: Architecture

HOWTO Recreate /dev/null

If something happens that requires you to recreate /dev/null on your *nix system. Don’t fret, it’s easy. The most recent issue I had was that a Capistrano recipe inadvertently clobbered /dev/null. The file looked like this: 12[root@web1 ~]# ls -l /dev/null -rw-r--r-- 1 capistrano engineering 0 May 26 04:02 /dev/null Thankfully to bring it back …

By eric

More Efficient SPAM Fighting with Amavisd-logwatch

This is the first in a multipart series on better SPAM fighting through log parsing. I have found that better Systems Administration can usually be achieved through proper log handling and analysis. In fact, I will use the data from one of the secondary mail servers in my personal mail setup in order to demonstrate …

By eric

Deploying Amavisd-logwatch

I was looking for way to make my SPAM filtering more effective and came across this great tool from Mike Cappella called amavisd-logwatch. On his web site, it says he doesn’t like waiting for package maintainers, so its just a tarball. Since my installs are Debian based, I created a deb for it. My .deb …

By eric

Tops and Tops (15 of Them)

There are so many variations on the original and good old useful version of Linux top that I figured I would list a few of the ones that I find handy on occasion. As with anything else, they all have their usefulness and each one can be more useful than any other at a particular …

By eric

What is a DRD

I have Google’d around asked a lot of smart people and still can’t come up with a solid answer. More specifically, the question I have is: Why, when sending emails to certain domains, do I get the error: 451 Could not load DRD for domain Because I deal with fairly large mailing lists, I see …

By eric

Setting Up DKIM and Postfix on CentOS 5.2

I spent a while trying to set up DKIM with Postfix on CentOS 5.2. I read the HOWTOs on HOWToForge written by Andrew Colin Kissa (aka TopDog) who subsequently helped me towards getting this setup working. My setup is that I have a mail spooler and multiple mail senders. This is to say that the …

By eric

Adding Yum to CentOS 5

I use a lot of VPS and often times, they don’t actually have yum to make my life easier. So here is a quick HOWTO on installing yum on a CentOS box. This assumes that you have rpm and wget already installed. Note: This will only work on CentOS 5.2 while the mirror is still …

By eric

Apache mod_proxy

I came up against the interesting problem of putting multiple stand alone apache tomcat instances with different virtual host names on the same machine that all needed to be accessible via port 80 (on the same IP). There is always mod_jk, but that seems like a bit too much to fix a simple problem. Being …

By eric

Deleting Lots Of Files (SysAdmin problem solving exercise)

Since I know I am not the first (or the last) to make a typo in logrotate and not catch it for a while…someone else must have been in the position of having to delete a lot of files in the same manner. I recently learned that, as usual, there is more than one way …

By eric

Cloning a Virtual Machine in VMWare VI3 without Virtual Server

I, like many other people working in a small company, have to fix problems and come up with solutions with cost at the forefront. I had to make many virtual machines appear from nowhere to create an environment in virtually no time at all. Since all I had was VMWare Server (for Linux), I started …

By eric

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