If you would like to disable IPv6 on RedHat Enterprise please do the following :

Add or Modify the file [ /etc/sysconfig/network ] :

NETWORKING_IPV6=no

 

Add the following line to [ /etc/sysctl.conf ]

net.ipv6.conf.all.disable_ipv6 = 1

 

On a running system you can do the following ( still need to do action above ) :

echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6

 

it is advisable NOT to to to the following to modify [ /etc/modprobe.conf ] :

alias net-pf-10 off
alias ipv6 off
options ipv6 disable=1

 

Reason for NOT modifying the [ /etc/modprobe.conf ] is that the IPv6 module has become so ingrained in the kernel that a number of other things, like certain firewall modules, require it.