How To: Lowering Your DNS TTLs

Whenever making DNS changes, lowering your TTLs (Time To Live) 24 hours ahead of time will reduce the amount of time that your change takes to propagate.
This article assumes that you are running BIND on a linux server, that you already have an understanding of what DNS is, the different types of DNS entries, and how DNS works. Please note: The incorrect editing of your zone file can take your site offline. All editing must be done on the authoritative nameservers for the given domain.

Continue reading “How To: Lowering Your DNS TTLs”

How to use Grep

Imagine you have a file. Perhaps it is a log file. It is long, and has much information in it. And buried somewhere in that file, there is one piece of information that you need to find. It would take far too long to read through the huge file. This situation cries out for some faster method of extracting that piece of information.

For this very task, Linux provides us grep.

Continue reading “How to use Grep”

Who’s SSHed Into My Server?

So you know how to ssh into your server. But how do you know if anyone else is shelled into your server?

If more than one person is shelled into a server, and all are trying to fix a problem, it is possible that they could step on each others’ toes. How horrible would it be if two people intending to fix the issue ended up making it worse? It would be grand if the shell provided a simple yet mighty command that displayed all of the users who are shelled in.

Continue reading “Who’s SSHed Into My Server?”

CSF: Config Server Firewall Installation

An alternative firewall to APF is the Config Server Firewall, or CSF.

CSF is generally considered a more advanced firewall as there are more configuration options compared to other firewalls, while still being simple enough to install and configure that even novice administrators can use it. This article will give you a simple overview about how to install and configure CSF and its security plugin LFD (Login Failure Daemon).

Continue reading “CSF: Config Server Firewall Installation”

cPanel How To: Change a Domain’s MX Record

This guide will walk you through the process of changing a domain’s Mail Exchange (MX) record(s) to point e-mail at a different server. MX records are a critically important part of a web site’s DNS because they tell the rest of the internet where to send e-mail for a domain.

Continue reading “cPanel How To: Change a Domain’s MX Record”