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This article mainly explains "how to disable IPv6 under Linux". The content in the article is simple and clear, easy to learn and understand. Please follow the editor's train of thought to study and learn "how to disable IPv6 under Linux".

Pv6 is considered to be a substitute for the traditional 32-bit address space on the IPv4-- Internet, which is used to solve the problem that the existing IPv4 address space is running out. However, since there are already a large number of hosts and devices connected to the Internet using IPv4, it is almost impossible to switch them all to IPv6 overnight. Many IPv4-to-IPv6 conversion mechanisms (e.g. dual stack, network tunnel, proxy) have been proposed to promote the adoption of IPv6, and many applications are being rewritten, as we advocate, to increase support for IPv6. One thing is certain, that is, IPv4 and IPv6 will coexist in the foreseeable future.

Ideally, the transition to IPv6 should not be seen by the end user, but IPv4/IPv6 mixed environments can sometimes cause you to encounter problems that arise from inadvertent collisions between IPv4 and IPv6. For example, you may encounter problems with application timeouts, such as failed apt-get or ssh attempts to connect through IPv6, DNS servers that accidentally empty IPv6's AAAA records, or your IPv6-enabled devices that are not compatible with the IPv4 network left behind by your Internet service provider, and so on.

Of course, this does not mean that you should blindly disable IPv6 on your Linux machine. Given the benefits promised by IPv6, we eventually have to embrace it fully as part of the community, but as part of the end-user troubleshooting process, if IPv6 is indeed the culprit, you can try to shut it down.

Here are some tips to disable IPv6 in some or all of your Linux (for example, for a particular network interface). These tips should apply to all major Linux distributions, including Ubuntu, Debian, Linux Mint, CentOS, Fedora, RHEL, and Arch Linux.

See if IPv6 is enabled in Linux

IPv6 is automatically enabled by default in all modern Linux distributions. To see if IPv6 is activated in your Linux, use the ifconfig or ip command. If you see the output with the word "inet6" after entering these commands, it means that your Linux system has IPv6 enabled.

The code is as follows:

$ifconfig

The code is as follows:

$ip addr

Temporarily disable IPv6

If you want to temporarily shut down IPv6 on your Linux system, you can use the / proc file system. "temporary" means that our changes that disable IPv6 will not be saved after the system restart. IPv6 will be enabled again after your Linux machine is rebooted.

To disable IPv6 on a specific network interface, use the following command:

The code is as follows:

$sudo sh-c 'echo 1 > / proc/sys/net/ipv6/conf//disable_ipv6'

For example, disable IPv6 on the eth0 interface:

The code is as follows:

$sudo sh-c 'echo 1 > / proc/sys/net/ipv6/conf/eth0/disable_ipv6'

Re-enable IPv6 for the eth0 interface:

The code is as follows:

$sudo sh-c 'echo 0 > / proc/sys/net/ipv6/conf/eth0/disable_ipv6'

If you want to disable IPv6 on all interfaces of the entire system, including the loopback interface, use the following command:

The code is as follows:

$sudo sh-c 'echo 1 > / proc/sys/net/ipv6/conf/all/disable_ipv6'

Permanently disable IPv6

The above methods can not permanently disable IPv6, once you restart the system IPv6 will still be enabled. If you want to turn it off permanently, there are several ways you can try it.

Method one

The first way is to make permanent changes to / proc through the / etc/sysctl.conf file.

In other words, open / etc/sysctl.conf with a text editor and add the following:

The code is as follows:

# disable IPv6 for all interfaces of the entire system

Net.ipv6.conf.all.disable_ipv6 = 1

# disable IPv6 of a specified interface (for example: eth0, lo)

Net.ipv6.conf.lo.disable_ipv6 = 1

Net.ipv6.conf.eth0.disable_ipv6 = 1

To make these changes take effect at / etc/sysctl.conf, run the following command:

The code is as follows:

$sudo sysctl-p / etc/sysctl.conf

Or just restart it.

Method two

Another way to permanently disable IPv6 is to pass a necessary kernel parameter at boot time.

Open / etc/default/grub with a text editor and add "ipv6.disable=1" to the GRUBCMDLINELINUX variable.

The code is as follows:

$sudo vi / etc/default/grub

GRUB_CMDLINE_LINUX= "xxxxx ipv6.disable=1"

The "xxxxx" above represents any existing kernel parameter, adding "ipv6.disable=1" after it.

Finally, don't forget to save your changes to GRUB/GRUB2 in the following ways:

Debian, Ubuntu, or Linux Mint systems:

The code is as follows:

$sudo update-grub

Fedora, CentOS/RHEL system:

The code is as follows:

$sudo grub2-mkconfig-o / boot/grub2/grub.cfg

Now as long as you restart your Linux system, IPv6 will be completely disabled.

Other optional steps after disabling IPv6

Here are some optional steps to consider after you disable IPv6, because when you disable IPv6 in the kernel, other programs may still try to use IPv6. In most cases, this behavior of the application doesn't affect much, but you can disable IPv6 for them for efficiency or security reasons.

/ etc/hosts

Depending on your settings, / etc/hosts will contain one or more hosts of IPv6 and their addresses. Open / etc/hosts with a text editor and comment out the script line that contains IPv6 hosts.

The code is as follows:

$sudo vi / etc/hosts

# comment these IPv6 hosts

#:: 1 ip6-localhost ip6-loopback

# fe00::0 ip6-localnet

# ff00::0 ip6-mcastprefix

# ff02::1 ip6-allnodes

# ff02::2 ip6-allrouters

Network Manager

If you are using NetworkManager to manage your network settings, you can disable IPv6 in NetworkManager. Open wired connection in NetworkManager, click the "IPv6 Settings" option and select "Ignore" in the "Method" column to save the exit.

SSH service

By default, the OpenSSH service (sshd) attempts to bundle the addresses of IPv4 and IPv6.

To force sshd to bind only IPv4 addresses, open / etc/ssh/sshd_config with a text editor and add the following line. Inet applies only to IPv4, while inet6 applies to IPv6.

The code is as follows:

$sudo vi / etc/ssh/sshd_config

AddressFamily inet

Then restart the sshd service.

Thank you for your reading, the above is the content of "how to disable IPv6 under Linux". After the study of this article, I believe you have a deeper understanding of how to disable IPv6 under Linux, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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