{{tag>networking ipv6 bridge}}

====== Set up IPv6 on host and VM ======

Prerequisites:

  - host with ipv6 subnet assigned
  - kvm/qemu virtal machines

===== Host machine =====

Identify the interface to which to assign the ipv6. In case you are using a bridge you need to use the bridge interface.

Set up bridge (install ''bridge-utils'' package)
  brctl addbr br0
  ip link set up dev br0

Add physical interface to bridge, here eth2 (adjust as necessary):
  brctl addif br0 eth2
  
<code>
# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.d05099fd8909       no              eth2
                                                        vnet0
                                                        vnet1
                                                        vnet2
                                                        vnet3
                                                        vnet4
                                                        vnet5
                                                        vnet6
</code>
Above we see the physical interface is eth2 and rest are vnets from created VMs from before. 

Now add ipv6 to bridge interface.

<WRAP center round tip 60%>
If you just want to use the v6 address on the interface itself you have to remove it from the bridge.
</WRAP>

We add the IP:
  ip -6 addr add 2607:5300:203:9cc9::/64 dev br0
This is subnet so you can choose an ip like 2607:5300:203:9cc9::1234. In this example the above is equal to ''2607:5300:203:9cc9::0'' IP address.

Add route to the v6 gateway itself (get it from the server provider)
  ip -6 route add 2607:5300:0203:9cff:00ff:00ff:00ff:00ff dev br0

then add default route:
  ip -6 route add default via 2607:5300:0203:9cff:00ff:00ff:00ff:00ff

Check
<code>
# ip -6 r
::1 dev lo proto kernel metric 256 pref medium
2607:5300:203:9cc9::/64 dev br0 proto kernel metric 256 pref medium
2607:5300:203:9cff:ff:ff:ff:ff dev br0 metric 1024 pref medium
fe80::/64 dev eth2 proto kernel metric 256 pref medium
fe80::/64 dev vnet0 proto kernel metric 256 pref medium
fe80::/64 dev br0 proto kernel metric 256 pref medium
fe80::/64 dev vnet1 proto kernel metric 256 pref medium
fe80::/64 dev vnet2 proto kernel metric 256 pref medium
fe80::/64 dev vnet3 proto kernel metric 256 pref medium
fe80::/64 dev vnet4 proto kernel metric 256 pref medium
fe80::/64 dev vnet5 proto kernel metric 256 pref medium
fe80::/64 dev vnet6 proto kernel metric 256 pref medium
default via 2607:5300:203:9cff:ff:ff:ff:ff dev br0 metric 1024 pref medium
</code>

===== Inside of VM =====

Assign an ip from the IPv6 subnet of the host. We chose ..:178 here:
<code>
# ip -6 addr add 2607:5300:203:9cc9::178/64 dev eth0                                                                                      
# ip a                                
1: lo: <LOOPBACK,UP,LOWER_UP> 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 02:00:00:a0:b6:a8 brd ff:ff:ff:ff:ff:ff              
    altname enp1s0                                                                 
    inet 51.161.64.178/32 scope global noprefixroute eth0        
       valid_lft forever preferred_lft forever               
    inet6 2607:5300:203:9cc9::178/64 scope global            
       valid_lft forever preferred_lft forever               
    inet6 fe80::ff:fea0:b6a8/64 scope link                   
       valid_lft forever preferred_lft forever
</code>

Now add default route. "via" is the IPv6 of the host interface br0.
<code>
# ip -6 route add default via 2607:5300:203:9cc9::0

# ping6 2001:4860:4860::8888                                                        
PING 2001:4860:4860::8888(2001:4860:4860::8888) 56 data bytes
64 bytes from 2001:4860:4860::8888: icmp_seq=2 ttl=113 time=1.24 ms
64 bytes from 2001:4860:4860::8888: icmp_seq=3 ttl=113 time=1.25 ms
64 bytes from 2001:4860:4860::8888: icmp_seq=4 ttl=113 time=1.25 ms                                                                                                    
64 bytes from 2001:4860:4860::8888: icmp_seq=5 ttl=113 time=1.25 ms
</code>

If any of the pings aren't working make sure to check if the firewall is blocking and you have ipv6 forwarding enabled on host.

====== Tested on ======
  * AlmaLinux 9
  * KVM/Qemu VMs

====== See also ======
  * [[add_additional_ip_address_interface|Add additional ip address on interface]]
====== References ======
  * https://access.redhat.com/sites/default/files/attachments/rh_ip_command_cheatsheet_1214_jcs_print.pdf
  * [[https://tools.keycdn.com/ipv6-ping|Ping6 test website]]