How to Enable IPv6 In CentOS / RHEL 5

Here is the step-by-step procedure to configure IPv6 in CentOS/RHEL 5.

1. Add the below entry in the modprobe.conf file

# vi /etc/modprobe.conf
alias net-pf-10 ipv6

Note : Remove if any entry like below in the modprobe.conf file:
#alias net-pf-10 off
#alias ipv6 off
#options ipv6 disable=1

2. Change the “NETWORKING_IPV6“” parameter value to yes in the netwok file.

# vi /etc/sysconfig/network
NETWORKING_IPV6=yes

3. Restart the networking service to enable the IPV6 support

# /etc/init.d/networking restart

4. Configure interface.
Append following config directives for IPv6 in /etc/sysconfig/network-scripts//ifcfg-eth#:

IPV6INIT=yes
IPV6ADDR=
IPV6_DEFAULTGW=