Configure IPv6 on virtual machines with ESXi

• compute
• dedibox
• esxi
• vm
• virtual-machine
• ubuntu

This tutorial explains how to configure IPv6 on virtual machines on ESXi hypervisors.

1. Log into your virtual machine using SSH.

2. Run the command ip a to display your current network configuration. The command returns an output as follows:

   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: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
   link/ether 00:50:56:01:fa:b9 brd ff:ff:ff:ff:ff:ff
   altname enp3s0
   inet your.fail.over.ip/32 scope global ens160
      valid_lft forever preferred_lft forever
   inet6 fe80::250:56ff:fe01:fab9/64 scope link
      valid_lft forever preferred_lft forever
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   Take note of the following information from the output above:

   • The name of the network interface (here ens160)
   • The local IPv6 of your VM (here fe80::250:56ff:fe01:fab9/64)

3. Open the file /etc/dhcp/dhclient6.conf in a text editor and edit it as shown below. Then save the file and quit the text editor.

   interface "ens160" {
       send dhcp6.client-id DUID;
   }
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   Important:

   Edit the name of the Internet interface to the one of your VM and replace DUID with the DUID of your prefix.

4. Open the file /etc/systemd/system/dhclient.service in a text editor and edit it as shown below. Then save and exit the editor.

   [Unit]
   Description=dhclient for sending DUID IPv6
   After=network-online.target
   Wants=network-online.target
   
   [Service]
   Restart=always
   RestartSec=10
   Type=forking
   ExecStart=/sbin/dhclient -cf /etc/dhcp/dhclient6.conf -6 -P -v eno1
   ExecStop=/sbin/dhclient -x -pf /var/run/dhclient6.pid
   
   [Install]
   WantedBy=network.target
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5. Enable the service to start automatically after each reboot of the machine. Then start the service manually for the first time.

   systemctl enable dhclient.service
   systemctl start dhclient.service
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6. Verify that the service is running with the following command:

   systemctl status dhclient.service
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   The command above returns an output as follows:

       ● dhclient.service - dhclient for sending DUID IPv6
       Loaded: loaded (/etc/systemd/system/dhclient.service; enabled; vendor pres>
       Active: active (running) since Thu 2022-02-24 12:18:03 UTC; 27min ago
     Main PID: 5342 (dhclient)
       Tasks: 4 (limit: 4627)
       Memory: 1.6M
       CPU: 23ms
       CGroup: /system.slice/dhclient.service
               └─5342 /sbin/dhclient -cf /etc/dhcp/dhclient6.conf -6 -P -v ens160
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7. Edit your Netplan configuration file (probably located at /etc/netplan/01-netcfg.yaml) and edit it as follows:

   network:
   version: 2
   renderer: networkd
   ethernets:
       ens160:
       dhcp4: false
       dhcp6: false
       addresses:
       - FAILOVER_IP/32
       - IP_FROM_YOUR_PREFIX/SUBNET
       gateway4: 62.210.0.1
       gateway6: LOCAL_IPv6
       nameservers:
           addresses: [62.210.16.6, 62.210.16.7]
       routes:
       - to: 0.0.0.0/0
           via: 62.210.0.1
           on-link: true
       - to: "::/0"
           via: "LOCAL_IPv6"
           on-link: true
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8. Apply the new network configuration with the following command:

   netplan apply 
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   You now have configured the IP address, but the IPv6 connectivity is not working yet.

9. Find the gateway for your prefix by running the following command:

   ip -6 route
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   The command returns an output as follows:

   ::1 dev lo proto kernel metric 256 pref medium
   YOUR_IPv6_PREFIX/SUBNETMASK dev ens160 proto kernel metric 256 pref medium
   fe80::/64 dev ens160 proto kernel metric 256 pref medium
   default via fe80::7a0c:f0ff:fedf:254d dev ens160 proto static metric 1024 onlink pref medium
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   Take a note of the default gateway (here fe80::7a0c:f0ff:fedf:254d).

10. Edit your Netplan configuration file again and modify it as follows:

    gateway6: DEFAULT_GATEWAY 
    - to: "::/0"
        via: "DEFAULT_GATEWAY"
        on-link: true
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    Note:

    Remember to replace DEFAULT_GATEWAY with the default gateway found in the previous step.

11. Reload your network configuration for the last time:

    netplan apply 
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You have now IPv6 connectivity for your virtual machine. You can test it by running a ping6: ping ipv6.google.com.