Debian: Disable IPv6

[^rooker]

For internal network computers, I disable IPv6 in most cases.

This here is basically just a copy of the "How to turn off IPv6" section on the Debian Wiki:

1) Edit /etc/sysctl.conf
and add the following parameters to kernel:

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net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

Note: This disables IPv6 on all network interfaces.
Optional: If you want to only disable it on specific ones, you can use a syntax like this:

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net.ipv6.conf.eth0.disable_ipv6 = 1

(This would apply only to "eth0" for example)

2) Apply changes:
After editing sysctl.conf, you should run sysctl -p to activate changes or reboot system.

That's it.

[^rooker]

Another option that I now find slightly cleaner than modifying "/etc/sysctl.conf" directly, is to use the "/etc/sysctl.d" folder to keep this config separately (and easier to enable/disable it).

1) Create a file called "/etc/sysctl.d/70-disable-ipv6.conf"

2) Put the same lines in that file as you would into sysctl.conf directly

3) Save it and either reboot or reload sysctl:

Code: Select all

$ sysctl -p -f /etc/sysctl.d/70-disable-ipv6.conf

Feels cleaner

[peter_b]

Here are some nice links with information about IPv6:

• Practical Networking for Linux Admins: Real IPv6 (linux.com)
• Practical Networking for Linux Admins: IPv4 and IPv6 LAN Addressing (linux.com)
• Test-IPv6.com
• IPv6 Range Blocks (MediaWiki Help)