Protecting Linux servers against SYN attacks and IP spoofing is surprisingly simple. Jack Wallen shows you how in a great tutorial.

The sysctl system allows you to make changes to a running Linux kernel. This utility reads and modifies various attributes of the kernel, such as version number, maximum limits, and a number of security settings. 

The sysctl system also allows you to prevent things like SYN flood attacks and IP address spoofing. It also logs several types of suspicious packets--spoofed packets, source-routed packets, and redirects.

You can modify kernel parameters at runtime with the sysctl command or you can make changes within the system's configuration file so those changes are more of a permanent nature.