The Firewall Kernel

Most distributions today include the firewall code in the standard kernel. Review your installation to see if that's true. If it is, you'll find the firewall modules in /lib/modules/ ${ kernel-version} /kernel/net/ipv[46]/. However, this text will cover the kernel just in case you decide to reconfigure it for yourself. Several parameters must be set in the kernel to permit packet filtering. Some of these are subjective and are based on your hardware; one must be turned off; others are required. For more information on building a custom kernel, see Chapter 18, "Building a Custom Kernel." The first parameter follows:

Code maturity level options -> Select developmental and/or incoomplete code/drivers

As of this writing, the ...

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