Unable to disable IPv6

Octavio Masomenos

2/8/24, 2:37 PM

I’ve tried everything I could find on permanently disabling IPv6. This page says to edit /etc/default/grub (then update grub and reboot). OK. Did that. And:

cat /etc/default/grub | grep ipv6

Returns:

GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"
GRUB_CMDLINE_LINUX="ipv6.disable=1"

Great! Should be disabled now! Nope.

ip -6 addr

Returns:

2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 fe80::e654:e8ff:fe0b:52c9/64 scope link 
       valid_lft forever preferred_lft forever

This page (supposedly specific to Ubuntu Server 22.04) says to add

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

to /etc/sysctl.conf then apply the changes and restart the network service. Did that. Then this command is supposed to prove that IPv6 is disabled:

cat /proc/sys/net/ipv6/conf/all/disable_ipv6

When it returns “1” (which it does). But still…

ip -6 addr

Returns

2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 fe80::e654:e8ff:fe0b:52c9/64 scope link 
       valid_lft forever preferred_lft forever

I tried rebooting. Still got the same output from ip -6 addr

What am I doing wrong? More importantly, how do I make it right?

256

0 + 2

server

grub2

networking

22.04

Pilot6

2/8/24, 2:38 PM

It is disabled. `fe80` is a local address.

Octavio Masomenos

2/10/24, 4:32 AM

Thank you, @pilot6. :-)

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Unable to disable IPv6

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