Linux primer for networkers

Computerworld - Installing, supporting and particularly diagnosing networks can involve much detective work, in addition to decent levels of frustration and caffeine. As with all investigations, the more data that is available to form and test hypotheses, the more likely a problem will be solved. Therefore, the more options or tools available for data gathering, the more useful the data obtained.

Open-source programs for Linux-based systems constitute some of the best tools available for network diagnosis, performance analysis and baseline determination. However, in my experience, the majority of network administrators today avoid Linux, perhaps intimidated by the process of setting up such a system.

This is a turnaround from 13 or so years ago, when networkers chose Linux simply because networking was built into the kernel of the operating system. Those who attempted IP networking in 1993 on a Windows 3.11 box, manually installing and configuring the network interface card (NIC) and loading a third-party IP stack (probably Trumpet Winsock), understand what I'm talking about.

While many excellent open-source diagnosis tools exist for Windows (Ethereal, for example), by shunning Linux, some essential tools are left off the workbench. A screwdriver, vice grips and a lot of muscle power can remove the spring that connects a deck to a riding mower, but a spring-removal tool is a lot easier and doesn't lead to the pain of skinned knuckles. Just as there is a small learning curve associated with using a spring puller, setting up a Linux system for network monitoring can be simple with a little guidance.

Linux distributions combine the Linux kernel with open-source packages and customized scripts to create servers and workstations. The kernel is customizable and can run on old Intel 386 processors, but for performance the target network machine should have at least a 667MHz processor, based on my experience.

Although distributions can be installed with a Windows-type graphical user interface to conserve resources (because one benefit is to use computers no one else has a use for), the installation should be text only, and not include installing any GUI software.

When choosing a distribution, factors such as cost, ease of installation, support and kernel version should be considered. Some add-on packages, such as Web100, require a certain version of kernel because it actually modifies the kernel (most packages do not).

Support doesn't necessarily mean a telephone number to call; most of the best support is in the form of FAQs, Web sites, mailing lists and discussion boards. Fedora Core is a great package, for example, for building network monitoring devices.