Howto disable IPv6 on Centos 6.4 or Redhat 6.4 RHEL
1. Check IPv6 on your Centos or RHEL Server
[root@Centos64 /]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:8b:33:58 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.111/24 brd 192.168.0.255 scope global eth0
inet6 fe80::20c:29ff:fe8b:3358/64 scope link
valid_lft forever preferred_lft forever
[root@Centos64 /]#
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:8b:33:58 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.111/24 brd 192.168.0.255 scope global eth0
inet6 fe80::20c:29ff:fe8b:3358/64 scope link
valid_lft forever preferred_lft forever
[root@Centos64 /]#
2. Disable IPv6 on Centos or Redhat Server
[root@Centos64 ~]# vi /etc/modprobe.d/disable-ipv6.conf
install ipv6 /bin/true
install ipv6 /bin/true
[root@Centos64 ~]# vi /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=Centos64
GATEWAY=192.168.0.1
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=Centos64
GATEWAY=192.168.0.1
[root@Centos64 ~]# echo “net.ipv6.conf.all.disable_ipv6 = 1″ >> /etc/sysctl.conf
[root@Centos64 ~]# init 6
3. Check your IP Address on your server after reboot
[root@Centos64 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:8b:33:58 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.111/24 brd 192.168.0.255 scope global eth0
[root@Centos64 ~]#
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:8b:33:58 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.111/24 brd 192.168.0.255 scope global eth0
[root@Centos64 ~]#