Disabling IPv6 in RHEL 5.5 and Fedora 12, 13

To disable IPv6 in RHEL 5.5:

1. Add the following lines to /etc/modprobe.conf:

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



2. It is also recommended to change /etc/sysconfig/network to read:

NETWORKING_IPV6=no

3. Finally, be sure to prevent the IPv6 firewall from coming back up on the next reboot by doing a:

/sbin/chkconfig ip6tables off


4. Then reboot.

To disable IPv6 in Fedora 12, 13

1. Create a file under /etc/modprobe.d (e.g. “blacklist-ipv6.conf”) with the following 2 lines, in the order shown:

install ipv6 /bin/true
blacklist ipv6

2. Then make sure /etc/sysconfig/network reads as described above.
You’ll also want to turn off ip6tables and use chkconfig to keep it off as described above (chkconfig ip6tables off).

3. Reboot once you’re done and all should be well in the world again.