IPv6 & Linux - HowTo - Part 2

Basic Software

Contents

• Linux distribution
• Kernel with IPv6 support

Needed software packages

• Linux distribution
• Kernel
• 2.2.x series: linux-2.2.19.tar.gz or later
• 2.4.x series: linux-2.4.5.tar.gz or later

Linux distribution

Why?

Version:

• e.g. Red Hat 6.2 or 7.1, don't forget to apply all available updates to close all known local and remote security holes!

Installation, changes and configuration:

• Install the distribution
• Red Hat 6.2-Installation: choose option: "Server"
• Run network setup to configure a working IPv4 network
• Additional installation of software under Linux with linuxconf or by hand with rpm -ihv packetname
• Before removing given packets, inform yourself about the content of the packet
• Contents: rpm -qi packetname
• List of files: rpm -ql packetname

Here are list of all packages I have installed on my hosts (perhaps it's useful for you):

• rpm-rh6v0-server.txt (without for installing IPv6 needed packages) - long time ago...

• Several adaptations:
• Edit /etc/lilo.conf
• Change vga=normal to vga=extended for screen terminals with 50 lines, after next reboot you see more of the kernel messages at once (only, if "General|Video mode selection support" is enabled during kernel configuration).
• Run lilo to put the changes of lilo.conf in the boot record

IPv6 ready kernel

Why?

Version and filename of the packet:

• 2.2.16 (IPv6 enabled)
• 2.2.19 + USAGI-Patch-20010403 (20010418 don't result in a successful compilation)
• 2.4.5 (+ndisc-linklocal-patch)

Because of security issues, you should update to 2.2.19+ immediately!

RedHat publishes already updates for RHL 6.2: e.g.ftp://updates.redhat.com/6.2/

Also I recommend to apply the related Openwall security patch, you can get it from ftp://ftp.openwall.com/pub/patches/linux/ (at the moment, only kernel versions 2.2.x are supported).

Additional Information:

If you want to compile this kernel as non-monolithic (using some kernel parts as modules), you need a new version of the modutils (2.1.121+).
Take care of the new module loader (called kmod) built-in in the kernel.
To avoid any problems, read the file Documentation/Changes from the kernel source and look, if your system-software is up-to-date.

The current standard kernel sources of 2.2.19- and 2.4.3- have bugs relating to automatic network configuration if an interface is shut down and started up again (problem known as does not re-join all-node multicast address on network devices after down and up again). USAGI-Patch will help in this case, too.

In 2.2.19- and 2.4.3- there is also a bug in ndisc.c, you will find patches here: ftp://ftp.bieringer.de/pub/linux/IPv6/kernel/
In 2.4.4+ there is another bug in ndisc.c, you will find patches here: ftp://ftp.bieringer.de/pub/linux/IPv6/kernel/

Contents:

Unpacking, configuration

• RedHat 6.2
• Install kernel source package
• rpm -ihv path-to-rpm-packages/kernel-source-version.rpm
• Goto kernel source directory
• cd /usr/src/linux
• Copy original config file (relating to your used CPU type)
• cp configs/kernel-version-cputype.config .config
• Apply patches...
• Configure the kernel for IPv6
• make config or make menuconfig
• Enable following options

Kernel options		Selection
Networking options	The IPv6 protocol	module (if cause problems, then use yes)
	IPv6: enable EUI-64 token format	yes (2.4.4-, removed 2.4.5+)
	IPv6: disable provider based address	yes (2.4.4-, removed 2.4.5+)

• Update Makefile with version number (otherwise you're running into a module version conflict), e.g.
• Change: EXTRAVERSION = -5.0

to: EXTRAVERSION = -5.0-IPv6
• Others
• Move into the source directory:
• cd /usr/src
• Remove the symbolic link to the old kernel sources:
• rm linux
• Unpack the new kernel source:
• tar xzf your-path/linux-version -C /usr/src
• If you have an older kernel source like described upper, you can apply now patches:
• gzip -cd your-path/patch-2.y.x.gz | patch -p0
• Rename the new created source directory for better distinction:
• mv linux linux-version
• Now create a softlink, necessary for compatibility afterwards:
• ln -s linux-version linux
• Move into the kernel source directory:
• cd linux
• Apply patches...
• Configure the kernel for IPv6
• make config or make menuconfig
Don't forget to set other options depending on your system, too!

Kernel options		Selection
Code maturity level options	Prompt for development and/or incomplete code/drivers	yes
Loadable module support	Enable loadable module support	no (fewer problems, but at the moment, I get no problems running as much as possible of the kernel as modules)
	[if modules are enabed] Set version information on all symbols for modules	yes (you should select this to prevent module mismatch, see also EXTRAVERSION later in the Makefile)
	[if modules are enabed] Kernel module loader	yes (normally kerneld is no longer used)
Cosole drivers	Video mode selection support	yes (so you can use the 50 line modus at the console, see lilo.conf options [vga=extended]  for details)
Networking options	Packet socket	yes or module  (important for tcpdump!)
	Unix domain sockets	yes (won't mostly work as module!)
	Kernel/User netlink socket	yes (needed by ip)
	Routing messages	yes (needed by ip)
	TCP/IP networking	yes
	The IPv6 protocol	module (if causing problems, then use yes)
	IPv6: enable EUI-64 token format	yes (2.4.4-, removed 2.4.5+)
	IPv6: disable provider based address	yes (2.4.4-, removed 2.4.5+)
File systems	/proc filesystem support	yes
Kernel hacking	Magic sysrq key	yes (very useful at hang-ups, read sysrq.txt for details)

• Make a backup of the kernel config:
• cp .config ../config-version-counter
• You can also create a new subversion (I prefer this now) with editing the Makefile
• vi Makefile
• Change/add EXTRAVERSION, i.e.

EXTRAVERSION = -IPv6
• Now compile the kernel:
• make dep; make clean; make {zImage | bzImage} <; make modules>

You can also use my utility coke for that.
Hint: Use bzImage, if kernel built would be too big
• If you get any errors during compilation, look at your kernel config and try some other options. Sometimes newer kernels are a little strange... It is also possible that it's better to build a non-modular kernel.
• Copy and name the kernel:
• cp arch/i386/boot/{zImage | bzImage} /boot/vmlinuz-version
• If you have build a kernel with modules you should install them now and build also the initial RAM disk:
• make modules_install
• mkinitrd /boot/initrd-2.2.19-6.2.1-IPv6.img 2.2.19-6.2.1-IPv6
• Edit /etc/lilo.conf or run liloconfig
• Add a new kernel entry for i.e. /boot/vmlinuz-ip6.

Beware of removing the old (and running) kernel. Sometimes a hangup during booting the IPv6 kernel (e.g. you forgot an important option to select...) can cause many trouble if you haven't a second (running) kernel to boot!
• Don't forget to add/edit an entry in /etc/lilo.msg.
• Create/overwrite the link to the new kernel:
• ln -sf /boot/vmlinuz-version /boot/vmlinuz-ip6
• Run lilo to put the changes of lilo.conf in the boot record
• Reboot the system and select the new IPv6 kernel (good luck):
• reboot