RHEL 6 IPv6 default source address

rhel6-ipv6-network

# Linux's default source address selection for multiple IPv6 addresses on the
# same interface leaves a lot to be desired. See:
# http://www.akkadia.org/drepper/linux-rfc3484.html
#
# The RFC 3484 method described there and used in gai.conf feels like the
# wrong way to me, so I used the approach documented here:
# http://www.davidc.net/networking/ipv6-source-address-selection-linux
# and mark all but the main IPv6 source address as "deprecated" so they
# won't be used as default source addresses (but otherwise function fine).
#
# We should be able to specify options like preferred_lft at address setup
# time for IPV6ADDR_SECONDARIES, but in file
# /etc/sysconfig/network-scripts/network-functions-ipv6
# function ipv6_add_addr_on_device does: /sbin/ip -6 addr add $address dev $device
# and doesn't allow for any options. 
#
# Thus the following is custom hacking which runs multiple times during network
# setup, since there is also no post-config-only hook we can use. Yes, in
# /etc/sysconfig/network.
#
IPV6ADDR=2a01:4f8:151:5384::2
the_device=eth0
ip -6 addr show dev $the_device \
    | grep 'inet6 ' | grep 'scope global' | grep -v "$IPV6ADDR" | grep -v deprecated \
    | sed 's/^\s*inet6 //; s/ .*//;' \
    | while read addr
do
    ip addr change $addr dev $the_device preferred_lft 0
done