March 2011

10 Useful Sar (Sysstat) Examples for UNIX / Linux Performance Monitoring

by Ramesh Natarajan on March 29, 2011

Using sar you can monitor performance of various Linux subsystems (CPU, Memory, I/O..) in real time.

Using sar, you can also collect all performance data on an on-going basis, store them, and do historical analysis to identify bottlenecks.
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Quick Info about the Upcoming eBook

by Ramesh Natarajan on March 28, 2011

For the past several months, I’ve been working on writing a book on the two great UNIX tools — Sed and Awk.

I’ve spend lot of sleepless nights to make this book easy to read and understand with lot of examples. It is almost complete and the book will be released very soon. Once you understand how to use Sed and Awk effectively, you’ll be knocking down lot of complex text manipulation tasks just by writing few lines of Sed or Awk code.
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10 Tips to Secure Your Apache Web Server on UNIX / Linux

by Ramesh Natarajan on March 22, 2011

If you are a sysadmin, you should secure your Apache web server by following the 10 tips mentioned in this article.
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Linux IPTables: Incoming and Outgoing Rule Examples (SSH and HTTP)

by Ramesh Natarajan on March 15, 2011

In our previous IPTables firewall series article, we reviewed how to add firewall rule using “iptables -A”.

We also explained how to allow incoming SSH connection. On a high-level, it involves following 3 steps.

  1. Delete all existing rules: “iptables -F”
  2. Allow only incoming SSH: “iptables -A INPUT -i eth0 -p tcp –dport 22 -j ACCEPT”
  3. Drop all other incoming packets: “iptables -A INPUT -j DROP”

The above works. But it is not complete. One problem with the above steps is that it doesn’t restrict the outgoing packets.
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Linux Performance Monitoring and Tuning Introduction

by Ramesh Natarajan on March 8, 2011

This is the 1st article in our new series on Linux performance monitoring and tuning.

Linux system administrators should be proficient in Linux performance monitoring and tuning. This article gives a high level overview on how we should approach performance monitoring and tuning in Linux, and the various subsystems (and performance metrics) that needs to be monitored.

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How To Install Apache 2 with SSL on Linux (with mod_ssl, openssl)

by Ramesh Natarajan on March 1, 2011

This article gives step by step instructions on how to install Apache 2 with mod_ssl.

I prefer to install Apache from source, as it gives me more flexibility on exactly what modules I want to enable or disable, and I can also upgrade or apply patch immediately after it is released by the Apache foundation.
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