How to configure IPv6 on OVH AlmaLinux 8 server

First, find the network interface used by the server with ip a command.

[root@15-204-47-122 ~]# ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno1:  mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether a8:a1:59:c0:de:80 brd ff:ff:ff:ff:ff:ff
    altname enp3s0f0
    inet 15.204.47.122/24 brd 15.204.47.255 scope global eno1
       valid_lft forever preferred_lft forever
    inet6 fe80::aaa1:59ff:fec0:de80/64 scope link
       valid_lft forever preferred_lft forever
3: enp3s0f1:  mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether a8:a1:59:c0:de:81 brd ff:ff:ff:ff:ff:ff
4: enp0s20f0u8u3c2:  mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 5a:58:d0:03:8e:b3 brd ff:ff:ff:ff:ff:ff
[root@15-204-47-122 ~]#

The interface eno1 has the public IPv4 address of the server associated, so it is the public interface used by the server.

Find the IPv6 IP address and gateway, This you can find in the OVH Manager server details page.

Edit ifcfg file for the network interface

vi /etc/sysconfig/network-scripts/ifcfg-eno1

At the end of the configuration, add

IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6_FAILURE_FATAL=no
IPV6ADDR=2604:2dc0:200:1f7a::/64

2604:2dc0:200:1f7a::/64 – is the IPv6 IP address found in OVH Manager.

Here is the full configuration

BOOTPROTO=static
DEVICE=eno1
HWADDR=a8:a1:59:c0:de:80
IPADDR=15.204.47.122
NETMASK=255.255.255.0
GATEWAY=15.204.47.254
ONBOOT=yes
TYPE=Ethernet
USERCTL=no
IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6_FAILURE_FATAL=no
IPV6ADDR=2604:2dc0:200:1f7a::/64

Create route file

vi /etc/sysconfig/network-scripts/route6-eno1

Add

2604:2dc0:0200:1fff:00ff:00ff:00ff:00ff dev eno1
default via 2604:2dc0:0200:1fff:00ff:00ff:00ff:00ff

Here ‘2604:2dc0:0200:1fff:00ff:00ff:00ff:00ff” is gateway address you get from OVH Manager server network page. eno1 is your public network interface name.

After reboot, the IPv6 network will work on the server.