Linux IP Masquerade HOWTO - The Linux Documentation Project

== Non−MASQ options skipped
== (I2C, Watchdog cards, Ftape, Video for Linux, etc. )
[ File systems ]
== Non−MASQ options skipped
== (Quota, ISO9660, NTFS, etc )
* /proc filesystem support (CONFIG_PROC_FS) [Y/n/?]
− YES: Required to dynamically configure the Linux forwarding
and NATing systems
== Non−MASQ options skipped
== (Console drivers, Sound, USB, Kernel Hacking)
So go ahead and select "exit" and you should be prompted to save your config.
NOTE: These are just the kernel components you need for IP Masquerade networking support. You will need
to select whatever other options needed for your specific setup. If you want more information on what each
one of these kernel modules does, please see the FAQ section of this HOWTO for details.
• Now compile the kernel (make dep; make clean; make bzImage; make modules; make
modules_install) , etc. Again, it is beyond the scope of this HOWTO if you have problems compiling
your kernel. Please see Section 2.6 for URLs to the KERNEL howto, etc.
• You will then have move over the kernel binary, update your bootloader (LILO, Grub, etc.), and
reboot. If you have questions about kernel compiling, I highly recommend to consult some of the
URLs mentioned above in this section.
3.2.2. Compiling Linux 2.2.x Kernels
Please see Section 2.7 for any required software, patches, etc.
• First of all, you need the kernel source for 2.2.x (preferably the latest kernel version)
•
♦ NOTE #1: −−− UPDATE YOUR KERNEL −−− Linux 2.2.x kernels less than version 2.2.20
contain several different security vulnerabilities (some were MASQ specific). Kernels less
than 2.2.20 have a few local vulnerabilities. Kernel versions less than 2.2.16 have a TCP root
exploit vulnerability and versions less than 2.2.11 have a IPCHAINS fragmentation bug.
Because of these issues, users running a firewall with strong IPCHAINS rulesets are open to
possible instrusion. Please upgrade your kernel to a fixed version.
♦ NOTE #2: As the 2.2.x train progressed, the compile−time options keep on changing. As of
this version, this section reflects the settings for a 2.2.20 kernel.
If you are running either a newer or older kernel version, the dialogs will look different. It is
recommended that you update to the newest kernel for added capability and stability of the
system.
Linux IP Masquerade HOWTO
If this is your first time compiling the kernel, don't be scared. In fact, it's rather easy and it's covered
in several URLs found in Section 2.7. Please note that the instructions included here is just one way to
do build a kernel. Please see the Kernel HOWTO for full details.
Chapter 3. Setting Up IP Masquerade 25