Disable or enable the IPV6 protocol in Red Hat Enterprise Linux

Resolution

Red Hat Enterprise Linux 4, 5 and 6 enable Internet Protocol Version 6 (IPV6) by default. However, in certain situations, some users could find it desirable to disable IPV6 support or to re-enable it after it had b Een disabled.

For Red Hat Enterprise Linux 6, the tech brief Preparing for IPv6 Networking in Red Hat Enterprise Linux provides a broad Introduction to IPV6 Networking.

Disabling IPV6 support in Red Hat Enterprise Linux 6

2. Create a file with the /etc/modprobe.d/ipv6.conf following contents:

   options ipv6 disable=1

4. For completeness, it's a good idea to configure the ip6tables service not to start at boot by issuing the following command:

   # chkconfig ip6tables off

6. Edit and add the line /etc/sysconfig/networkNETWORKING_IPV6=no

8. Disable IPv6 support in the kernel through /etc/sysctl.conf :

   # ipv6 support in the kernel, set to 0 by defaultnet.ipv6.conf.all.disable_ipv6 = 1net.ipv6.conf.default.disable_ipv6 = 1

10. Optionally to prevent rpc.nfsd setting up IPV6 sockets while NFS server was running, edit for the /etc/netconfig lines starting with UD P6 and TCP6; Change the of the "v" third column to "-" (Hyphen/dash)

12. Reboot the system to disable IPV6 support.

Note:there is a special case where this might isn't work, please see the "IPv6 disable=1" option does not seem to work on R Ed Hat Enterprise Linux 6 system.
Disabling IPv6 in the sysctl.conf would ensure IPv6 isn ' t used even if the IPv6 module is loaded and can work as a short te RM solution (until a full reboot)

Re-enabling IPv6 support in Red Hat Enterprise Linux 6

2. Review the files under and /etc/modprobe.d/ remove (or comment out) any of the following lines:

   options ipv6 disable=1install ipv6 /bin/trueblacklist ipv6

4. Configure the ip6tables service to start at boot by issuing the following command:

   # chkconfig ip6tables on

6. Edit and add the line /etc/sysconfig/networkNETWORKING_IPV6=yes

8. Make sure the following options to your is /etc/sysctl.conf

   # ipv6 support in the kernel, set to 0 by defaultnet.ipv6.conf.all.disable_ipv6 = 0net.ipv6.conf.default.disable_ipv6 = 0

10. Edit for the /etc/netconfig lines starting with UDP6 and TCP6; change the "-" (Hyphen/dash) in the third column to"v"

12. Reboot the system to activate IPV6 support.

Disabling IPV6 support in Red Hat Enterprise Linux 5

2. Remove the following line (if present) from the /etc/modprobe.conf file:

   alias net-pf-10 ipv6

4. Add the following line to the /etc/modprobe.conf file:

   alias net-pf-10 off

6. In versions of Red Hat Enterprise Linux before 5.4, add the following line to the /etc/modprobe.conf file:

   alias ipv6 off

8. In Red Hat Enterprise Linux 5.4 and later, add the following line to the /etc/modprobe.conf file:

   options ipv6 disable=1

10. To prevent errors during the network Initscript start routine, change the parameter in the file to the NETWORKING_IPV6 /etc/sysconfig/network followi Ng

    NETWORKING_IPV6=no

12. For completeness, it's a good idea to configure the ip6tables service not to start at boot by issuing the following command:

    # chkconfig ip6tables off

14. Reboot the system to disable IPV6 support.

Re-enabling IPv6 support in Red Hat Enterprise Linux 5

1. Remove the following lines (if present) from the /etc/modprobe.conf file:

   alias net-pf-10 offalias ipv6 offoptions ipv6 disable=1

2. Add the following line to the /etc/modprobe.conf file (if not present already):

   alias net-pf-10 ipv6

3. The parameter in the file to the NETWORKING_IPV6 /etc/sysconfig/network following:

   NETWORKING_IPV6=yes

4. For completeness, it's a good idea to configure the ip6tables service to start at boot by issuing the following command:

   # chkconfig ip6tables on

5. Reboot the system to re-enable IPV6 support.

Disabling IPV6 support in Red Hat Enterprise Linux 4

1. Remove the following line (if present) from the /etc/modprobe.conf file:

   alias net-pf-10 ipv6

2. Add the following line to the /etc/modprobe.conf file:

   alias net-pf-10 off

3. Reboot the system to disable IPV6 support.

Re-enabling IPv6 support in Red Hat Enterprise Linux 4

1. Remove the following line from the /etc/modprobe.conf file:

   alias net-pf-10 off

2. Add the following line to the /etc/modprobe.conf file:

   alias net-pf-10 ipv6

3. Reboot the system to re-enable IPV6 support.