How to disable IPv6 on Linux

VPN servers of the MultiVPN network operate only using the TCPv4 protocol. If your ISP provides you with IPv6 addresses together with IPv4, to avoid information leaks, you must disable the IPv6 protocol.

First of all, you need to check if you have enabled IPv6 support. Try the following links:

https://ipv6.google.com - should not open in a browser

https://www.test-ipv6.com - online check IPv6

If checking IPv6 showed that this protocol is not available for you, you can skip reading this material. Otherwise, I recommend disabling IPv6 support.

Open a terminal. First of all, you should get superuser rights:

Using Ubuntu Linux as an example:

  user@ubuntu:~$ sudo bash
  [sudo] password for user:
  root@ubuntu:/home/user# id
  uid=0(root) gid=0(root) groups=0(root)
  root@ubuntu:/home/user#

For example, Fedora Linux:

  [user@localhost ~]$ su
  Password:
  [root@localhost user]# id
  uid=0(root) gid=0(root) groups=0(root)
  [root@localhost user]#

Add the following lines to /etc/sysctl.conf:

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

Command for "root" on one line to add the specified parameters and apply them via "sysctl -p":

echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf && echo "net.ipv6.conf.default.disable_ipv6 = 1" >> /etc/sysctl.conf && echo "net.ipv6.conf.lo.disable_ipv6 = 1" >> /etc/sysctl.conf && sysctl -p

After the done manipulations, again check the availability of IPv6, as indicated at the beginning of this material.

Linux instructions

Connecting to MultiVPN on Ubuntu Linux

Connecting to MultiVPN on Fedora Linux

OpenVPN Traffic Leak Blocking on Linux

Configure MultiVPN DNS servers on Linux