how to configure ipv6 address in centos 8

How to configure ipv6 address in Linux (RHEL / CentOS 7/8)

January 2, 2024

Linux , How To , Tips and Tricks

This step by step by guide to configure IPv6 address is validated on RHEL and CentOS 7 .

IPv6 can act as a replacement for the IPv4 network protocol. The major problem it solves is the exhaustion of IPv4 addresses by using a much larger network address space. It also provides a number of enhancements and new features for network configuration management and support for future protocol changes.

The key reason IPv6 is not yet in wide deployment is that the core protocol does not have a simple way for systems that only have IPv6 addresses to communicate with systems that only have IPv4 addresses.

An IPv6 address is a 128-bit number , normally expressed as eight colon-separated groups of four hexadecimal nibbles (half-bytes). Each nibble represents four bits of the IPv6 address, so each group represents 16 bits of the IPv6 address.

To make it easier to write IPv6 addresses, leading zeros in a colon-separated group do not need to be written. However at least one nibble must be written in each field. Zeros which follow a non zero nibble in the group do not need to be written.

Since addresses with long strings of zeros are common, combine one or more groups of consecutive zeros with exactly one :: block.

Notice that under these rules 2001:1:1:1443::400 would be another less convenient way to write the example address. But it is a valid representation of the same address, and this can confuse administrators new to IPv6.

Some tips for writing consistently readable addresses

Always suppress all the leading zeros in a group
Use :: to shorten as much as possible. If two runs of zeros are equal in length, shorten the leftmost run of zeros by preference.
Although it is allowed, do not use :: to shorten one group of zeros, Use :0: instead, and save :: for runs of zeros longer than a single group.
Always use lowercase letters for hexadecimal numbers a through f .

Pre-requisite before starting to configure IPv6 address

Make sure that IPv6 is enable on your node. Look out for below entry in your sysctl configuration

This will list the IPv6 status for the default value and per interface value.

Here " 0 " means IPv6 is in active on our node, if the above returns " 1 " then it means IPv6 is disable on your node. So if the IPv6 is disable then your IPv6 configuration will not work.

I have already written an article with steps to enable or disable IPv6

Comparison of nm-setting and ifcfg-* directives

The following table maps some of the key NetworkManager settings name relevant to IPv6 connections to ifcfg-* directives.

nmcli con mod	ifcfg-* file	Effect
manual	=no	IPv6 is configured statically
auto	=yes	Will configure network settings using SLAAC from router advertisements.
dhcp	=no =yes	Will configure network settings by using DHCPv6, but not SLAAC
"2001:db8::a/64 2001:db8::1"	=2001:db8::a/64 =2001:db8::1	Sets static IPv6 Address and Gateway
		Modify to use this
example.com	=example.com	Modify to use to use this domain in the directive
true	=no	Ignore DNS server information from the DHCP server
yes	=YES	Automatically activates the connection at boot
eth0	=eth0	The name of this connection
eth0	=eth0	The connection is bound to this network interface with this name
		The connection is bound to the network interface with this MAC Address

Configure IPv6 address using Network Manager.

Open Network Manager Console from your Linux node

Select Edit a Connection and click on Ok

How to configure ipv6 address in Linux (RHEL / CentOS 7/8)

Next look out for your Ethernet card on which you wish to configure IPv6 address. If your NIC card does not appear on the list then you can add a new device . Since for me my device ( eno50 ) exists, so I will select the device and select Edit

This will bring you the main configuration page where you must give all the details to configure IPv6 address. Since I do not want to add IPv4 address to the same Ethernet device, I have disabled the IPv4 option.

Provide the IPv6 address/subnet and the gateway . Make sure you select Automatically Connect

Lastly click OK to exit the utility.

Next restart the network services to activate the changes

Now let us check the network configuration of eno50

So looks like I was able to successfully configure my interface with IPv6 address.

Validate the connectivity by pinging the IPv6 gateway

So I am able to connect to my gateway which means my IPv6 configuration was successful.

Configure IPv6 address using CLI

The following command will add a new connection for the interface eno49 , which will auto connect at startup, getting IPv4 networking information using DHCPv4. It will also get IPv6 networking settings by listening for router advertisements on the locallink.

The below command configures the eno49 interface statically using the IPv6 address and network prefix 2001:1:1:1443::433/122 and default IPv6 gateway 2001:1:1:1443::43F , but it still auto connects at startup and saves its configuration into /etc/sysconfig/network-scripts/ifcfg-eno49 .

Let us validate our configuration by pinging the gateway using eno49 interface

Again with the CLI looks like the steps are successful for me.

Modify existing IPv6 configuration

In the below command we are changing the IPv6 address of our interface eno49 from 2001:1:1:1443::433 to 2001:1:1:1443::434 , while the gateway remains the same.

Restart the eno49 interface

Next bring the the interface

Validate the new IP address for eno49 device

Check the connectivity from eno49 to it's gateway

Check the configuration file for eno49

I hope the steps from the article to configure IPv6 address on Linux (CentOS/RHEL 7/8) was helpful. Let me know your suggestions and feedback using the comment section.

Deepak Prasad

He is the founder of GoLinuxCloud and brings over a decade of expertise in Linux, Python, Go, Laravel, DevOps, Kubernetes, Git, Shell scripting, OpenShift, AWS, Networking, and Security. With extensive experience, he excels in various domains, from development to DevOps, Networking, and Security, ensuring robust and efficient solutions for diverse projects. You can connect with him on his LinkedIn profile.

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6 responses to “How to configure ipv6 address in Linux (RHEL / CentOS 7/8)”

One update for Centos 8. Change systemctl restart network to systemctl restart NetworkManager.service

I really love your website.. Very nice colors & theme. Did you make this amazing site yourself? Please reply back as I’m planning to create my very own site and want to know where you got this from or exactly what the theme is called. Kudos!

For us noobs: the network should be restarted after the address setup:

service network restart

Thanks for your feedback, I have updated the article 🙂

How did you get /122 when creating the new ip address and same gateway example?

This is the gateway and subnet provided by our network team.

Configuring an IPv6 address in Red Hat Enterprise Linux 7 and 8

%t min read | by Valentin Bajrami (Sudoer alumni)

Configuring an IPv6 Address in RHEL 7 and 8

As I mentioned in What you need to know about IPv6 , different methods exist to configure an IPv6 address on a machine. We will mainly focus on configuring an IPv6 address on a Red Hat Enterprise Linux (RHEL) 7 and 8 systems and briefly explain different assignment methods.

[Want to try out Red Hat Enterprise Linux? Download it now for free.]

Configuring IPv6 on RHEL 7 and 8

A Red Hat Enterprise Linux system is configured to obtain an IPv6 address automatically. These are the lines in the configuration file where the magic happens (I am adding some explanation to each line):

For more information on what those connection settings do, run:

Stateless address autoconfiguration (SLAAC)

If the IPV6_AUTOCONF variable is set to yes , then the SLAAC method is used to configure the host’s IPv6 address by using the Neighbor Discovery Protocol (NDP) . The technique applied here is the one explained in the previous article’s Multicast section, where there is an exchange of client solicitation and router advertisement ICMPv6 messages.

We use the term stateless because there is no service to keep track of what IPv6 addresses have been assigned to clients. Rather, the IPv6 address is composed with a technique called the Extended Unique Identifier (EUI-64) where 16 bits are added to the Media Access Control (MAC) address (which has 48 bits), thus creating a globally unique IPv6 address.

To use DHCPv6, the following should appear within the configuration file:

If the DHCPv6 variable is set to yes , then a client obtains an IP address from the DHCPv6 pool. The DHCPv6 service then keeps track of what IPv6 addresses are assigned to what clients. Among the IP address, other information like DNS servers, lease time, hostnames, and other attributes are pushed to the client. An administrator must configure the IPv6 address pool to be able to serve clients.

It is also possible (but not recommended) to configure an IPv6 address manually. Manual configuration requires a lot of effort, is error-prone, and it’s hard to keep track of what IPv6 addresses are assigned to what clients. On a large network, a DHCPv6 server is preferable for performing this task.

To configure IPv6 on Red Hat Enterprise Linux 7 and 8 manually, your version of the following needs to added to the configuration file:

Or, you can manually configure through NetworkManager:

Testing IPv6 connectivity

To test IPv6 connectivity, we can run a ping6 on www.redhat.com :

While the ping was running, I ran Wireshark in the background to see what’s happening under the hood. Here is the ICMPv6 request packet (sent by me) and the ICMPv6 reply packet I received back.

ICMPv6 request

Icmpv6 reply.

Note that many organizations choose to block ping requests for security reasons, so it’s generally a good idea to try pinging several sites when testing your connectivity.

Valentin Bajrami

Valentin is a system engineer with more than six years of experience in networking, storage, high-performing clusters, and automation. He is involved in different open source projects like bash, Fedora, Ceph, FreeBSD and is a member of Red Hat Accelerators. More about me

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Adding an ipv4 or ipv6 address to centos 8.

When you order an extra IPv4 address or add an extra IPv6 address to your IP addresses via the TransIP control panel , these cannot be automatically added to your VPS via DHCP. Additional IP addresses are added manually to the network interfaces.

In this article, we explain how you can statically add an extra IPv4 or IPv6 address to your CentOS 8 VPS . For this, an extra IPv4 and/or IPv6 address is required (depending on which you'd like to add / configure). Don't have an extra address yet? The following articles explain how you can get one:

Ordering an extra IPv4 address in the control panel
Creating an extra IPv6 address in the control panel

Click here for a complete overview of all our tutorials for adding an extra or static IPv4 or IPv6 address to various Linux distros. For adding an IPv4 or IPv6 address to a Windows VPS, see this article .

This manual is about public IP addresses. In this manual , you will find more information about setting up internal addresses (for your private network).
Please note: in the steps in this article the adapter is called ens3 . In your installation this may be eth0 . Make sure to check this using the ip a command and if necessary change ens3 to eth0 where applicable.

A VPS includes 1 IPv4 address by default, but you can expand this to a maximum of 10 IPv4 addresses via the control panel. A maximum limit of 20 IPv4 addresses applies to the VPSs of the PRO series.

Each VPS has a /64 IPv6 range at its disposal by default, where IP addresses can be added as desired. A /64 IPv6 range contains a total of 18,446,744,073,709,551,616 IP addresses, so the likeliness that you will not have enough is quite small! The default gateway falls outside of the /64 range so as netmask you always use a /48 range.

Adding an IPv4 address in CentOS 8

Connect to the VPS via the VPS console or via SSH .

Once logged in you see the current network interfaces and the configured IPs by using the command:

For the next steps, it is especially important that you are aware of the correct adapter name. Which is ens3 in this example.

Please note: Did you use our fast installs feature for VPS and chose for installation via SSH-keys, one time password, or cloud-config user data ? Then, additional steps are required. Click ' Fast installs proces ' below to view these steps.

For Fast Installs we make use of Cloud Init . Cloud Init automatically overwrites your netwerk configuration. For this reason Cloud Init or its control over the network (either choice is fine) must be disabled as follows:

Disabling Cloud Init network management

Open/create the following file:

Give the file the following contents. Afterwards, save and close your file ( ctrl + x > y > enter ).

Disabling Cloud Init

Cloud Init is only used for the initial installation of your VPS. It can't hurt as such to disable it altogether. All that's required to disable Cloud Init is the creation of the following file:

Should the changes not take affect after completing this tutorial, the following command may be required:

Now add the extra IPv4 address in the network interfaces. First, open the network configuration file:

Add/adjust the following to the existing configuration file:

IPADDR(x) is the IP address that you want to set and GATEWAY(x) the gateway, which for your IP address can be found in the control panel .
For every IP address that you add, you use an ascending number, i.e. IPADDR1, IPADDR2, IPADDR3, etc. The same applies to gateways if applicable. You need to leave the (sub)NETMASK at 255.255.255.0.
You are not required to add a gateway if the IP is part of the same /24 range. If it isn't, you are required to set the gaeway.

Save the changes and exit nano ( ctrl + x > y > enter ).

Reset your network interfaces with the following command to use the new IP address:

NMCLI is the command-line tool for NetworkManager. A restart via systemctl restart NetworkManager won't work unfortunately. If ens3 is active the following commands may work instead:

If you run ip a again you will see the newly added IPv4 address. You can test this IP address by performing a ping test from another computer / IP.

Repeat the above steps if you want to add more IP addresses.

Adding an IPv6 address in CentOS 8

For the next steps, it is especially important that you are aware of the correct adapter name. Which is ens3 in this example.

Now add the extra IPv6 address in the network interfaces. First, open the network configuration file:

In the opened configuration file, add the following lines if they are missing (replacing the IPv6 address by your server's primary IPv6 address):

Save the changes and exit nano ( ctrl + x > y > enter ). If you want to add more IPv6 addresses, add the following line (placing all additional addresses between the brackets):

Restart your server to se the IPv6 addresses. Restarting your network with nmcli or systemctl doesn't process the changes.

If you run ifconfig -a or ip addr again you will see the newly added IPv6 address. You can test this IP address by performing a ping test from another computer / IP.

Repeat the above steps if you want to add more IP addresses.

Should you have any questions left regarding this article, do not hesitate to contact our support department. You can reach them via the ‘ Contact Us ’ button at the bottom of this page.

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How to configure a static IP address on RHEL 8 / CentOS 8 Linux

There are many cases in which we may want to set a static IP for a network interface. In RHEL 8 / CentOS 8, the network connections are managed by the NetworkManager daemon, so in this tutorial we see how we can perform such task by editing an interface file directly, by using a command line utility, nmcli , or via a text user interface, nmtui .

In this tutorial you will learn:

How to set a static IP address by directly editing an interface file
How to set a static IP address using the nmcli utility
How to set a static IP address using nmtui

Software Requirements and Conventions Used

Software Requirements and Linux Command Line Conventions
Category	Requirements, Conventions or Software Version Used
System	RHEL 8 / CentOS 8
Software	All the software mentioned in this tutorial is included in a minimal installation of or CentOS 8.
Other	Permission to run command with root privileges.
Conventions	– requires given to be executed with root privileges either directly as a root user or by use of command – requires given to be executed as a regular non-privileged user

Introduction

In Red Hat Enterprise Linux 8, network interfaces are managed by the NetworkManager daemon, so to change a network interface settings we must somehow interact with it. In this tutorial we will see how can we set a static IP address, gateway and dns server for a NIC by using different three methods.

Identifying our interface

The first thing we want to do is to find the interface we want to modify. To list all the interfaces on our system, we can use the ip addr command:

In the output above, which is the result of running the command on my rhel8 virtualized machine, we can see two interfaces: lo and enp1s0 . The first is a “virtual” interface, which is used by the system to “talk” with itself. The second one is the one which interests us, and currently its IPv4 address is 192.168.122.189: we want to change it.

Method 1 – modifying interface configuration file manually

For each network interface managed by the NetworkManager daemon, a configuration file is created inside the /etc/sysconfig/network-scripts directory. The name of the file is composed by the ifcfg- prefix plus the name of the interface. If we inspect the file related to our NIC, we can see its actual setup:

The BOOTPROTO option is set to dhcp : the option sets the protocol to use at boot to set the IP address of the interface. The possible options to use are:

none – No protocol should be used
bootp – Use the bootp protocol
dhcp – Use the dhcp protocol

Since we want to set a static IPv4 address, we want to change the value of BOOTPROTO to none and configure our IP, route prefix, gateway and dns server statically. We can accomplish this by using respectively the IPADDR , PREFIX , GATEWAY and DNS options. Since many dns servers can be specified, the DNS option must be reported together with a progressive number, starting from 1. After the needed modifications, our file should look like this:

We set our static IP to 192.168.122.66 and set both our gateway and dns server to 192.168.122.1 . Now, to make our changes effective we must put down and up again the network interface. Be aware that this will disrupt existent ssh connections via said interface:

By running the ip addr command again we can verify the IP has changed:

Method 2 – using nmcli

Nmcli is a command line tool used to control NetworkManager. By using it we can, among other thins, change network settings for a specific interface. In our case we must use nmcli with the connection subcommand with the modify or the edit action. The first lets us change the settings directly, while the second launches the nmcli shell, where we can operate interactively.

Using nmcli directly

To change the IP address of the “enp1s0” interface with a direct nmcli command, we run:

Notice that we specified the routing prefix together with the IP using the so called CIDR notation (Classes Inter-Domain Routing). We use a similar syntax to change the gateway and the dns settings:

Finally, we set the method to manual to avoid using any other boot protocol for the interface. This command sets the BOOTPROTO option to none in the interface configuration file:

Using nmcli shell

As we mentioned above, we can also use an interactive method to perform the same changes. To enter the nmcli shell we use the edit action, followed by name of the interface we want to edit:

The blinking cursor tells us the shell is accepting commands: we can type help to get a list of the available ones, print to see all the connection properties or describe followed by a setting and one of its properties (represented with a dot notation), to get a description of the latter. For example:

To change the address of our interface:

The same principle is used to change the other properties:

To save the modifications we made, we need to issue one last command:

To exit the nmcli shell just type quit and press enter:

Again, to make the changes effective, we should reload the interface with the same command we used before.

Method 3 – using nmtui

Other than changing the parameters of a network interface by modifying its file manually or by using the nmcli utility, we can also control NetworkManager by using a text user interface. To launch it we just invoke nmtui in our terminal:

We Select Edit a connection and then the name of the interface we want to manipulate; we then proceed in changing the desired values. For example:

After we are satisfied, we select OK and press enter: we will be taken back to the interface selection menu. This time we select back , and then choose quit to exit. To apply the settings we need to reload the interface connection:

Conclusions

In this tutorial we saw three methods we can use to set a static IP address on Red Hat Enterprise Linux 8. We see what options we should change and what we should add in the interface configuration file when editing it manually, and how to perform the same changes using nmcli and nmtui, which are respectively a command line utility and a text user interface: both are used to control the NetworkManager daemon.

How to Configure IPv6 Network on CentOS/RHEL 8 - DesignLinux

IPv6 addressing was developed in anticipation of depletion of the IPv4 addresses. It is meant to solve the exhaustion of IPv4 addresses through the use of a much wider network addressing space. An IPv6 address is a 128-bit number comprising 8 colon-separated groups each made up of 4 hexadecimal numbers.

Read Also : What’s wrong with IPv4 and Why we are moving to IPv6

An example of an IPv6 address is shown below:

IPv6 is usually enabled by default on CentOS/RHEL 8 . To check if IPv6 is enabled on your system, run the command:

Check IPv6 Support in RHEL 8

The value 0 indicates that IPv6 is active on your node. A value of 1 shows that IPv6 is disabled. Therefore, from the output above, IPv6 is enabled.

Another method of checking if IPv6 is enabled is by viewing your network interface at the /etc/network-scripts/ directory. In our case, this will be the /etc/sysconfig/network-scripts/ifcfg-enps03 file.

So let’s execute the command below and check if IPv6 is enabled.

Be on the lookout for the folIowing IPV6 options as shown:

IPV6INIT=yes – This initializes the interface for IPv6 addressing.
IPV6_AUTOCONF=yes – This enables the IPv6 auto-configuration for the interface.
IPV6_DEFROUTE=yes – This indicates that the default IPv6 route has been assigned to the interface.
IPV6_FAILURE_FATAL=no – indicates that the system won’t fail even when IPv6 fails.

Check IPv6 Support

The output above confirms that IPv6 addressing is enabled. On the terminal, you can check the IPv6 address of your interfaces by running the IP commands below.

Be on the lookout for the inet6 prefix as shown below.

Check IPv6 IP Address

To temporarily disable IPv6, run the command:

Disable IPv6 Address

To enable IPv6, run the command:

Then restart NetworkManager for the changes to apply.

Enable IPv6 Address

To permanently disable IPv6, edit the GRUB /etc/default/grub file. In the line, GRUB_CMDLINE_LINUX , append the argument ipv6.disable=1 at the end of the line as shown.

Disable IPv6 Address Permanently

To apply the changes, reboot your system.

Just like IPv4 , a manual configuration of IPv6 is possible using the nmtui and nmcli tools. However, this is not recommended because the manual configuration of IPv6 is prone to errors and is quite arduous.

Furthermore, it’s quite a task keeping track of which IPv6 addresses are assigned to what systems. Chances are that you are likely to mess up your configuration.

How to Install and Configure Memcached on CentOS 8

How to configure ip network with ‘nmtui’ tool.

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How do I configure a network interface for IPv6?

Environment

Red Hat Enterprise Linux 6
How do I configure IPv6 IP addressing?
How do I do basic IPv6 setup?

You can configure an IPv6 interface with the /etc/sysconfig/network-scripts/ifcfg-* files just like IPv4 addresses.

The following parameter is needed when configuring IPv6:

You can add an IPv6 address with:

The prefix is optional.

You can add the IPv6 gateway with:

Or if you want to specify the gateway interfaces as well, you can add it:

You add a DNS server like normal:

Diagnostic Steps

Example of ipv6 working with ipv4 in Red Hat Enterprise Linux 7 with NetworkManager.
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Configure ipv6 addresses and basic troubleshooting in linux.

In the past many system administrators have simply resorted to disabling IPv6 rather than properly configuring it, continuing to rely on the older IPv4 which has worked just fine for a very long time. As the IPv4 address space has since become exhausted, administrators are starting to slowly take up IPv6 out of necessity.

Here we’re going to cover how to configure IPv6 addressing in Linux and provide some basic tips and advice for troubleshooting IPv6 network issues.

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In this example we are working with CentOS 7.

Configuring IPv6 Addresses

IPv6 addresses can be configured in a few additional ways when compared with IPv4, some of these are listed below.

Manual Configuration: This is fairly similar to the way IPv4 is manually configured, essentially we manually edit an interface file in the /etc/sysconfig/network-scripts/ifcfg-<interface> format.
DHCPv6: Dynamic Host Protocol Version 6 is similar to DHCP for IPv4 in that it will automatically configure our interface.
Stateless Address Autoconfiguration (SLAAC): This works similar to DHCP, however it works by receiving router advertisement messages from a local IPv6 router on the network.

Here we will primarily be focusing on manual IPv6 network configuration.

Manual IPv6 Configuration

First take a look in the /etc/sysconfig/network-scripts/ directory to see if there is already existing IPv6 configuration for the particular interface in question. The file name will be listed as ifcfg-<interface>, you can confirm the interface names by running ‘ip a’ or the deprecated ‘ifconfig’. Typical names may include eth0, or the newer ‘eno*’ format such as eno16777736. This file can contain both IPv4 and IPv6 configuration for the same interface.

Below is the configuration of my CentOS 7 /etc/sysconfig/network-scripts/ifcfg-eno16777736 file, note the settings that start with “IPV6”.

IPV6INIT=yes – This is needed when configuring IPv6 on the interface.
IPV6ADDR=<ipv6-address> – Specifies a primary static IPv6 address.
IPV6_DEFAULTGW=<ipv6-address>%eno16777736 – Adds a default route through the interface specified.

Note that if you manually edit these files, you’ll need to run ‘nmcli con reload’ to pickup the changes. Alternatively we can make changes with the nmcli command, which admitedly takes some getting used to, but is quite powerful and its tab autocomplete helps a lot.

The first command sets the IPv6 address, while the second ensures that this is a static address and is not lost from DHCP or SLAAC.

For further information, keep the ‘nmcli-examples’ man page in mind, as there are a number of different examples documented here that you can make use of.

Automatic IPv6 Configuration

Automatic configuration of IPv6 addresses can take place with DHCPv6 or SLAAC. Below is some default configuration from CentOS 7 which has IPV6_AUTOCONF enabled, this configures network settings using SLAAC router advertisements.

Alternatively we can set IPV6_AUTOCONF to no, and define DHCPV6C=yes to use DHCPv6 rather than SLAAC. When using SLAAC or DHCPv6, the manual configuration items such as IPV6ADDR and IPV6_DEFAULTGW can be removed as these will be automatically configured.

For further information on these variables you can check out the documentation in /usr/share/doc/initscripts-*/sysconfig.txt

Applying Network Changes

After making any changes to the files in /etc/sysconfig/network-scripts/ the network needs to be restarted for them to take effect.

You could also perform a system reboot however this will take longer, but will bring the interface up with the new configuration.

Basic IPv6 Troubleshooting

Here are some basic tools you can use to perform basic IPv6 troubleshooting, they work fairly similarly to their IPv4 counterparts.

The ping6 command works in the same way as the normal ping command, except that ping6 works with IPv6 addresses. This can be used to send ICMP traffic to an IPv6 address and check for reply, the below example pings the IPv6 localhost address.

We can also ping out of a specified interface, the below command pings everything connected to eno1677736.

IPv6 Routes

The ‘ip -6 route show’ command can be used to display IPv6 routing.

IPv6 Traceroute

The traceroute6 command can be used to show all hops in the path to the specified destination in the same way as the traceroute command.

The tracepath6 command works in a similar manner.

View Current IPv6 Address Information

You can display current IPv6 configuration by running the ‘ip a’ command which is short for ‘ip address show’. This will show IPv6 interfaces as ‘inet6’ followed by their IP address.

View IPv6 Network Connections

By default the ‘netstat’ command shows both IPv4 and IPv6, however with the -6 option we can select to only display the ports that the server is listening on with its IPv6 addresses as well as any connections.

Configuring IPv6 addresses is not that much different to configuring IPv4 addresses, the main difference is simply the structure of the IP addresses is different. Once you pick up the basics of IPv6 you can easily configure IPv6 networking. Most of the troubleshooting tools are also pretty similar, you can still view the current IP address information, routing tables, and perform pings and traceroutes in a very similar manner.

This post is part of our Red Hat Certified Engineer (RHCE) exam study guide series. For more RHCE related posts and information check out our full RHCE study guide .

5 Comments.

I’d advise to use nmcli rather than edit files manually. For example:

# nmcli c mod eth0 ipv6.method manual ipv6.addresses fc00::a:a:a:10/64

I’ve ended up here looking to figure out how to troubleshoot traceroute6 returning “Network is unreachable”, and ironically in your troubleshooting section, it shows that same response. For references for others who end up here and puzzled, it is (most likely) due to the route to gateway is invalid or not added (or removed). A simple ‘route add -A inet6 default gw {your_local_IPv6_GW} dev {your_iface}’ should do the job to quick fix, though I’m still trying to troubleshoot the root cause of the routing table to not get configured correctly.

Thanks for letting me know, I hope you can sort it out.

I dont prefer using nmcli because in “real job” situations most companys have NM disabled. But for just passing an exam it,s ok…

a good article about IPv6 DHCP

Help article

Adding an ipv4 or ipv6 address to centos 8.

Ordering an extra IPv4 address in the control panel
Creating an extra IPv6 address in the control panel

This manual is about public IP addresses. In this manual , you will find more information about setting up internal addresses (for your private network).
Please note: in the steps in this article the adapter is called ens3 . In your installation this may be eth0 . Make sure to check this using the ip a command and if necessary change ens3 to eth0 where applicable.

A VPS includes 1 IPv4 address by default, but you can expand this to a maximum of 10 IPv4 addresses via the control panel. A maximum limit of 20 IPv4 addresses applies to the VPSs of the PRO series.

Adding an IPv4 address in CentOS 8

Connect to the VPS via the VPS console or via SSH .

Once logged in you see the current network interfaces and the configured IPs by using the command:

For the next steps, it is especially important that you are aware of the correct adapter name. Which is ens3 in this example.

Disabling Cloud Init network management

Open/create the following file:

Give the file the following contents. Afterwards, save and close your file ( ctrl + x > y > enter ).

Disabling Cloud Init

Cloud Init is only used for the initial installation of your VPS. It can't hurt as such to disable it altogether. All that's required to disable Cloud Init is the creation of the following file:

Should the changes not take affect after completing this tutorial, the following command may be required:

Now add the extra IPv4 address in the network interfaces. First, open the network configuration file:

Add/adjust the following to the existing configuration file:

IPADDR(x) is the IP address that you want to set and GATEWAY(x) the gateway, which for your IP address can be found in the control panel .
For every IP address that you add, you use an ascending number, i.e. IPADDR1, IPADDR2, IPADDR3, etc. The same applies to gateways if applicable. You need to leave the (sub)NETMASK at 255.255.255.0.
You are not required to add a gateway if the IP is part of the same /24 range. If it isn't, you are required to set the gaeway.