Log into your dedicated or cloud server via SSH.

##Edit /etc/sysconfig/network and set “NETWORKING_IPV6” to “no”

##For 5.4 and later, replace in /etc/modprobe.conf

alias ipv6 off

by

options ipv6 disable=1

Alternative (which might be easier and works on any release with /etc/modprobe.d):

# touch /etc/modprobe.d/disable-ipv6.conf

# echo “install ipv6 /bin/true” >> /etc/modprobe.d/disable-ipv6.conf

##For CentOS 5.3 or older, add the following to /etc/modprobe.conf :

alias ipv6 off

alias net-pf-10 off

##Run /sbin/chkconfig ip6tables off to disable the IPv6 firewall

##Reboot the system

<!> With the 5.4 update symbol/ipv6 module dependency capabilities have been introduced; therefore, if IPv6 has been previously disabled as above an upgrade to the bonding driver in 5.4 will result in the bonding kernel module failing to load. For the module to load properly use instead:

# touch /etc/modprobe.d/disable-ipv6.conf

# echo “options ipv6 disable=1” >> /etc/modprobe.d/disable-ipv6.conf

<!> <!> Upstream employee Daniel Walsh recommends not disabling the ipv6 module but adding the following to /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6 = 1