How to configure the IPv6 on a KVM slave?

Question

How to configure the IPv6 network on a KVM slave?

Answer

Warning: The steps below includes reboot of the networking service that can cause remote connection. Make sure that there is an alternative option to access the server like IPMI

Note: IPv6 addresses pool along with gateway should be provided by Data Center

1. Connect to the Slave node over SSH.

2. Modify the file /etc/sysconfig/network so that it has the following content:

   CONFIG_TEXT: NETWORKING_IPV6=yes
   IPV6FORWARDING=yes
   IPV6_DEFAULTDEV=br0
   IPV6_DEFAULTGW=aaaa:bbbb:a01a::1
   IPV6_AUTOCONF=no

   where aaaa:bbbb:a01a::1 - the necessary IPv6 gateway.

3. Modify the file /etc/sysconfig/network-scripts/ifcfg-br0 by adding the following lines:

   CONFIG_TEXT: IPV6INIT=yes
   IPV6ADDR=aaaa:bbbb:cccc:0000:0100::1

   where aaaa:bbbb:cccc:0000:0100::1 - the necessary IPv6 address for the slave node.

4. Modify the file /etc/sysctl.conf by adding the following lines:

   CONFIG_TEXT: net.ipv4.ip_forward=1
   net.ipv6.conf.all.forwarding=1
   net.ipv6.conf.br0.forwarding=1
   net.ipv6.conf.default.forwarding=1
   net.ipv6.conf.all.proxy_ndp=1

   Note: the first line may be already present in the file, do not add it in that case

5. Execute the following commands to apply changes:

   # sysctl -p
   # service network restart

6. (For Hetzner servers only) Create a file /etc/sysconfig/network-scripts/route6-br0 with the following content:

   CONFIG_TEXT: fe80::1 dev br0
   default via fe80::1

7. Check the IPv6 connection from the slave node:

   # ping6 ipv6.google.com -c3