Setup IPv6 on CentOS 7 in a ESXi-VM by OVH

Tobias asked:

Yesterday i orderd a new dedicated server at OVH for a small network with virtual machines powered by ESXi.

Today i created my first VM with CentOS 7 that works fine so far. I’m able to ping Google with IPv4, but i can not get the IPv6-Connectivity to work.

My Configuration (Guest):

Device: ens160
IP: 145.239.XXX.XX/32
Gateway: 217.182.XXX.254 (Host)
IPv6: 2001:41d0:700:XXX:x
Netmask: 64
Gateway: 2001:41d0:700:XXff:ff:ff:ff:ff (as suggested by OVH)

I’m not able to ping the default gateway.
What am i missing? I’m really new to this ESXi-thing, so please be kind.

My answer:

The IPv6 gateway address that OVH uses is outside the /64 that is routed to your dedicated server. Therefore, you need to configure a static route to the gateway address.

On RHEL/CentOS and Fedora, you can configure static IPv6 routes with a /etc/sysconfig/network-scripts/route6-<interface> file. This file literally contains route additions that will be passed to ip route. For example:

From /etc/sysconfig/network-scripts/ifcfg-eno1 (only IPv6 configuration shown):


From /etc/sysconfig/network-scripts/route6-eno1:

2607:5300:60:62ac::/64 dev eno1
2607:5300:60:62ff:ff:ff:ff:ff dev eno1
default via 2607:5300:60:62ff:ff:ff:ff:ff dev eno1

During OS installation, if you simply configure the IPv6 address, prefix 64 and gateway address as given by OVH, the installer will create the necessary static routes for you.

View the full question and answer on Server Fault.

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