How to disable IPv6 for all interfaces?

Support & Help Requests
#1

I tried different methods I found on the internet to disable IPv6 completely, but without success. It seems that the tips on the internet are no longer valid for Ubuntu MATE 16.04.

I created the file /etc/sysctl.d/60-disable-ipv6.conf:
net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1

But when I look up e.g. the ethernet interface with sysctl, then it is still set to 0 and only “all”, “lo” and “default” are set to 1. It seems like the “all” / “default” settings are not applied to the existing interfaces. I know I could add the respective interfaces to this file too, but I am looking for a general solution that disables IPv6 completely without having to specify each interface specifically.

Thus I also created the file /etc/modprobe.d/aliases (as it did not exist):
alias net-pf-10 off alias ipv6 off

as well as the file /etc/modprobe.d/blacklist-ipv6.conf:
blacklist ipv6 install ipv6 /bin/false

But neither of them had any effect, as I can still see e.g. an inet6 address for my ethernet interface. Any ideas which is the correct way to disable IPv6 on Ubuntu MATE 16.04?

#2

Can you not do it within grub?

GRUB_CMDLINE_LINUX_DEFAULT=“ipv6.disable=1”

I’d say try it manually on next startup, see if it sticks before writing it into boot.

I guess the big question though, is: why would you want to?

#3

Thanks. That works - seems that IPv6 is very tightly integrated, if that is the only way to completely disable it.

With regards to your question: My whole LAN is currently using static IPv4 addresses and comprises only a few computers. Thus there is no benefit from having IPv6 up and running - on the contrary, I can stick with the current firewall setup as I do not need to set up rules to tame IPv6. And I am a fan of the principle of minimizing the attack surface by disabling / uninstalling any piece of software / service that I do not need.

#4

See also: