OVH IPV6 is not enabled by default, but they do give you IPV6 ips. However by default IPV6 is CentOS 7’s default Internet Protocol, and as long as you haven’t turned it off, CentOS 7 tries to send traffic through IPV6 first, before using its fallback IPV4. This can greatly slow down the server as it waits for a response from IPV6, first it times out, then tries IPV4. Usually 30-90 seconds! All while app users wait for your server to respond. Luckily I have the solution right here.
SOLUTION TO ENABLE IPV6 OVH DEDICATED SERVER
1) Go to your OVH control panel and look for the ipv6 address in the IP section. (See top image.)
2) Now run this command:
ip -6 addr add YOUR_IPV6_ADDRESS/64 dev eth0
This will add the ipv6 address to your network device.
3) You now have to manually add the default gateway. To get the OVH servers IPV6 address, you simply remove the last two characters of the ipv6 address and put all FF:FF:FF:FF:FF’s in place. So if your IP looks like this 2607:5200:40:2d5e::/64 remove the “5e::/64” add the F’s and you have the default gateway.
Default Gateway = 2607:5200:40:2dFF:FF:FF:FF:FF
4) Now add a default route via this gateway:
ip -6 r a default via 2607:5200:40:2dFF:FF:FF:FF:FF
5) Add a default route:
route -A inet6 add default gw 2607:5200:40:2dFF:FF:FF:FF:FF dev eth0
6) Alternatively if that doesn’t work you may need to run this command first:
ip -6 r a 2607:5200:40:2dFF:FF:FF:FF:FFF dev eth0
7) Now you can add the default route via this gateway:
ip -6 r a default via 2607:5200:40:2dFF:FF:FF:FF:FF
But this did not add the IPV6 gateway, I had to edit this file /etc/sysconfig/network manually
nano /etc/sysconfig/network
Add this to the file:
NETWORKING_IPV6=yes IPV6_DEFAULTGW=2607:5200:40:2dFF:FF:FF:FF:FF
8) You may also need to edit this file /etc/sysconfig/network-scripts/ifcfg-eth0:
nano /etc/sysconfig/network-scripts/ifcfg-eth0
Add this
IPV6INIT=yes IPV6_AUTOCONF=no IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no IPV6ADDR="2607:5200:40:2d5e::1/64" IPV6ADDR_SECONDARIES="2607:5200:40:2d5e::5/64" IPV6_DEFAULTGW=2607:5200:40:2dFF:FF:FF:FF:FF
9) Restart the network:
systemctl restart network
10) Finally test if IPV6 is functional on the server by pinging Google:
ping6 -c 4 ipv6.google.com
CONCLUSION
Why isn’t OVH IPV6 functional on an OVH Server by default? Answer: They don’t think IPV6 is important enough YET to be setup by default (as do many other internet services). Deployment of IPV6 is beginning to spread though it still going to be some time before it is utilized as the default choice. Perhaps something or someone will come along and force the change over, but until then we are stuck with both IPV4 and IPV6.
References:
https://known.phyks.me/2014/getting-ipv6-to-work-with-a-kimsufi-server
http://help.ovh.com/Ipv4Ipv6
http://docs.ovh.ca/en/guides-network-ipv6.html
https://www.skyminds.net/serveur-dedie-mise-en-place-de-lipv6/