How to Setup milter-greylist Spam Blocking in Sendmail

Virtually all linux distributions include sendmail as the default MTA. Which is okay – it has been around for a long time, is stable and it works great (although the postfix afficionados might disagree!). But it has nothing built in for spam control which is good; it was not designed for that. So you’ve installed spamassassin and it works good but you still are getting unflagged spam emails through. Perhaps you need to try greylisting.

How to Prevent Yum from Updating the Kernel

When you’re running production servers, the one thing you don’t want to do is upgrade the kernel every time a new update comes out. Why? Because that’s the only Linux update operation that requires a reboot once it’s done—and in a production environment you often can’t have downtime.

How to Change Your Linux Hostname Without Rebooting

If you’ve worked in the admin world for any length of time, you’ve probably run into an instance where you needed to change the hostnames on your server to match some corporate naming standard, but you can’t have downtime either. So how do you change the hostname without rebooting?

Diagnose Linux Server Load Problems with a Simple Script

If you have been an admin for any length of time, you have certainly discovered situations where a server spikes in CPU use or memory utilization and/or load levels. Running `top` won’t always give you the answer, either. So how do you find those sneaky processes that are chewing up your system resources to be able to kill ’em?