To use firewalling, as well as installing iptables, you will need to configure the relevant options into your kernel. This is discussed in the next part of this chapter - . If you intend to use IPv6 you might consider extending the kernel by running make patch-o-matic in the top-level directory of the sources of iptables. If you are going to do this, on a freshly untarred kernel, you need to run yes "" | make config && make dep first because otherwise the patch-o-matic command is likely to fail while setting up some dependencies. If you are going to patch the kernel, you need to do it before you compile iptables, because during the compilation, the kernel source tree is checked (if it is available at /usr/src/linux-[version] to see which features are available. Support will only be compiled into iptables for the features recognized at compile-time. Applying a kernel patch may result in errors, often because the hooks for the patches have changed or because the runme script doesn't recognize that a patch has already been incorporated. Note that for most people, patching the kernel is unnecessary. With the later 2.4.x kernels, most functionality is already available and those who need to patch it are generally those who need a specific feature; if you don't know why you need to patch the kernel, you're unlikely to need to! Download (HTTP): Download (FTP): Download size: &iptables-size; Estimated Disk space required: &iptables-buildsize; Estimated build time: &iptables-time;