How to configure and secure your Postfix email server

How to configure and secure your Postfix email serverOnce you have your application server up and running, you are going to need a good email server to deliver your emails. I have been using postfix for all my servers and below is the configuration I generally use. Installation of Postfix on CentOS 6 yum install postfix Sendmail is installed by default, so it... Read More »

How to configure and Install Config Server Firewall & Login failure Daemon

How to configure and Install Config Server Firewall & Login failure DaemonWhenever I setup a Linux VPS, the first thing I do is install a firewall. I have noticed an increase in attacks on my servers, especially from China. I use Config Server Firewall (CFG) and Login Failure deamon (LFD) because they are easy to set up and provide additional features like suspicious file reporting and... Read More »

How to create Init Scripts

How to create Init ScriptsIn my last article, I used “inotifywait” along with rsync to create a real time file syncing script called backup. This script will run till I manually kill it or till I close my terminal, if I run it as a background process. Now I cannot keep my terminal open forever, but I want my... Read More »

How to use inotify-tools to trigger scripts on filesystem events

How to use inotify-tools to trigger scripts on filesystem eventsIn my last example of Bash if statements we created a backup script which would run “rsync” as per the time set in a cron. But wouldn’t it be nice if we could run our “rsync” script only if there was a change to the files in our directory instead of running a cron every... Read More »

How to display a changing output like top

In my earlier post on linux memory management, I showed you how you can get the exact memory usage of your script by using py_mem.py. This script, without any options will run once and give you the current memory usage of the system. But what if you wanted real time memory usage?, In other words,... Read More »

Advance text processing examples in awk

Advance text processing examples in awkLast week I was reading up on awk and was fascinated by its text processing capabilities despite been written more than 3 decades ago. Although, I mostly use awk for printing columns while troubleshooting a DDOS attack or to find high number of connections from an IP, netstat -ntu | awk '{print $5}' | cut... Read More »