[CentOS] Disabling IPv6 in Centos 4.x Experiences

http://lists.centos.org/pipermail/centos/2006-September/069975.html

Hi there,

While I was looking "how to disable ipv6 under centos" I have found a
gazzillion pages about how to do it and some of then even list things that i
am not sure where they came from, so for the record I list most of them here
in case someone else need them.
Some of the methods involved the direct modification of system scripts, and
I am against that so I wont list them here (removing the entire section of
ipv6 calls in IFUP is not a good idea).

How to disable ipv6 support in Centos 4.x
Pick any method, a combo or all of them

Method 1, add the line:
alias net-pf-10 off
to the /etc/modprobe.conf

Method 2 Add to /etc/sysconfig/network file:
NOZEROCONF=yes # Bonus: Disable the ugly generation of 169.254 zeroconf
networks.
NETWORKING_IPV6=no

Note about method 2. I must mention the fact that I actually READ the entire
ifup script and dependencies and I found that it calls at line 361:
# if [ "${NETWORKING_IPV6}" = "yes" ]; then
# /etc/sysconfig/network-scripts/ifup-ipv6 ${CONFIG}

However adding the NETWORKING_IPV6=NO has no effect whatsoever because even
after a reboot the interfaces continue to load an ipv6 address. BTW it does
the same for zeroconf and doesn`t work either.

Method 3:
/etc/sysconfig/network-scripts/ifcfg-XXXXX file;
IPV6INIT=no


So pick your best method or a combo and let us know which one worked for
you:
In my case Centos 4.3 2.6.9-34.EL i386 with a pair of 3COM 3c905CX lan
boards did not responded to Method 1 and 2 and 3. So I'm still battling with
this ipv6 thing.