Security Strategies in Linux Platforms and Applications, 3rd Edition

Increasing Security Using Kernels and the /proc/ Filesystem

Besides creating a custom kernel, you can do more with it to help secure Linux systems. One method uses the dynamic kernel options documented in the /proc/ directory filesystem. Although the /proc/ directory includes information on detected hardware, currently running processes, memory, and more, actual kernel options are shown in /proc/sys/ subdirectories. For example, the status of the /proc/sys/net/ipv4/ip_forward file determines whether Internet Protocol version 4 (IPv4) packets are forwarded through the system.

Most kernel configurable files in the /proc/sys/ directory are Boolean. In other words, they have a value of 0 or 1. If the file is active, its value is 1. Therefore, to ...