[CentOS] Disabling IPv6 in Centos 4.x Experiences

Aleksandar Milivojevic alex at milivojevic.org
Mon Sep 11 11:06:51 UTC 2006

Erick Perez wrote:

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

This is the right way to do it.

> Method 2 Add to /etc/sysconfig/network file:
> NOZEROCONF=yes      # Bonus: Disable the ugly generation of 169.254 
> zeroconf networks.
> 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.

It doesn't work on its own since as soon as first IPv6-capable daemon 
(for example sshd) attempts to bind to the ports, the ipv6 kernel module 
gets loaded and it will assign all interfaces default link local 
addresses to all interfaces.

However, do note that apart from deleting ipv6.ko from the disk, there's 
no good way to get rid of IPv6 for sure.  Even with the both of the 
above, if somebody/something does "modprobe ipv6", the module gets 
loaded and it does its thing with link local addresses.  Once it is 
loaded it is next to impossible to unload it from the running system.

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