initscripts-addrlabel

Add support to initscripts for IPv6 protocol address label management to allow source address selection.

KERNEL ADDRESS LABELS

IPv6 address labels are used for source address selection;

By default, IPv6 addresses have 'lifetime' counters, which are valid_lft and preferred_lft, normally set to 'forever'.

Because of this, the IPv6 interface address that was added most recently to the kernel will be used as the source address for outbound connections.

To modify this behaviour, you have the option to use kernel address labels, for controlling how networks (prefixes) are found from what interface address.

RECOMMENDATIONS BEFORE USING ADDRESS LABELS

Make sure the hosts you enter here are resolvable via DNS or /etc/hosts You can also check name resolution with the ip -6 -r addrlabel command.

Set multi on in /etc/host.conf (should be default)

MORE INFORMATION

The ip-addrlabel(1), gai.conf(5), and getaddrinfo(3) manpages.

RFC 3484 and 6724 at http://ietf.org

INSTALLATION

From these sources, copy sysconfig/network-scripts/ifup-routes to /etc/sysconfig/network-scripts/, thus overwriting the existing script, unless you would fancy a backup of the original.

Create a file /etc/sysconfig/network-scripts/addrlabel6-<dev>

Add prefixes to this file conform ip-addrlabel, without the 'ip' command itself, using a syntax similar to 'route-' etc. configuration files.

DEFAULT KERNEL POLICY TABLE

Below the policy table as described in RFC 6724, present in the kernel. You can examine the present table with 'ip addrlabel' or 'ip addrlabel show'.

   addrlabel add prefix ::1/128       label  0
   addrlabel add prefix ::/0          label  1
   addrlabel add prefix 2002::/16     label  2
   addrlabel add prefix ::/96         label  3
   addrlabel add prefix ::ffff:0:0/96 label  4
   addrlabel add prefix 2001::/32     label  5
   addrlabel add prefix fec0::/10     label 11
   addrlabel add prefix 3ffe::/16     label 12
   addrlabel add prefix fc00::/7      label 13

EXAMPLE 1

You can add a label for your own IPv6 networks at, say label 20, and then a label your IPv6 interface address at label 21, to ensure that this address is selected as source for outbound connections to this network.

   addrlabel add prefix 2a01:ab12:cd34::/48       label 20
   addrlabel add prefix 2a01:ab12:cd34:e56::1/128 label 21

EXAMPLE 2

To connect from 2a01:: to 2001:: with a preferred source address, the label of your 2a01-source needs a lower value than the label of the 2001-prefix..

   addrlabel add prefix 2a01:ab12:cd34:e56::1/128 label 1

LIMITATIONS

Yes

AUTHOR

Pieter Krul

THANK YOU

Satoshi Shida San (http://sshida.com)

SEE ALSO

https://bugzilla.redhat.com/show_bug.cgi?id=583441