A new article on deeper analysis of network packets, is now available on IBM developerWorks:

Whether you are monitoring your network to identify performance issues, debugging an application, or have found an application on your network that you do not recognize, occasionally you need to look deep into the protocols being used on your UNIX® network to understand what they are doing. Some protocols are easy to identify and understand, even when used on non-standard ports. Others need more investigation to understand what they are doing and what information they are exchanging. In this article, we will take a look at techniques for performing detailed analysis of the protocols in use on your UNIX network.

The piece specifically looks at ways of extracting more detailed information from the raw data you see on your network.

Read Deep-protocol analysis of UNIX networks

I have a new tutorial on analyzing networks, in terms of understanding your basic network configuration, the other machines and devices on the network, and the general topology.

From the intro:

When accessing a new UNIX system, or even understanding an existing one, a key part of the puzzle to how the system operates is the network configuration. There are many aspects of the network that you need to know and understand to correctly identify problems and prevent future problems. By using some basic tools and commands you can determine a lot about the configuration of a single system, and through this basic understanding, a good idea of the configuration of the rest of the network. With some additional tools, you can expand that knowledge to cover more systems and services within your network.

In this tutorial you will use some basic tools within the UNIX environment that can disclose information about the configuration of your system. By understanding these tools and the information they output, you will be able to gain a greater understanding of your system network configuration and how it works. You will also examine tools and solutions that can look at the wider network and gain more detailed information about your network, its potential security issues, and key points of information that will help you identify and diagnose problems when they do occur.

Read UNIX network analysis

Tracing applications are something of a passion for me, especially with the introduction of DTrace in Solaris and Mac OS X.

To support that, I have a new tutorial about the different methods available for tracing Unix applications. I tried to concentrate on tools and techniques that don’t require access to the source, like using truss and DTrace.

From the intro:

Most developers and systems administrators know what should happen in their operating system and with their applications, but sadly, this isn’t always the case. There are times when an application has failed, or is not behaving as you expect, and you need to find out more information. By using your existing knowledge of how your application should work and some basic UNIX skills, you can trace the application to find out what is causing the problem. This tutorial will teach you the basic techniques of using tracing tools to find out what your application is doing behind the scenes.

First, the tutorial looks at the distinction between debugging and tracing, and how the two solutions differ. Then it examines some specific examples of where tracing can be used to solve problems in your application. DTrace provides elements of both system tracing and debugging, and also provides you with the ability to time and benchmark applications. Finally, the tutorial shows how to trace the information being exchanged between network computers to help find problems in network applications.

Read Solutions for tracing UNIX applications