How to catch Linux system intruders

There's no doubt that Linux is a secure operating system. However, nothing is perfect. Millions of lines of code are churned through the kernel every second and it only takes a single programming mistake to open a door into the operating system. If that line of code happens to face the Internet, that's a backdoor to your server.

Patches are often released quicker and more often for Linux systems than they are for proprietary products. This is because anyone can take a look at the code – and thousands of developers regularly do. This 'many eyes' approach, which was advanced by Linus Torvalds, means that problems like back doors are usually found quickly. It also means that fixes are released just as quickly.

There's been a very vocal debate on the Linux kernel mailing list recently, with developers arguing about whether security bugs that are fixed should be formally announced and documented. Torvalds believes that making a big song and dance about security patches attracts the attention of miscreants like bees to honey. Others believe that anything but complete openness goes against the philosophy of Free Software.