Disable IPv6 in CentOS8

Introduction

A memo when I took the time to investigate the subject

First of all, the royal road

First, as a common pattern, execute the following to reboot

/etc/sysctl.conf

net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1
net.ipv6.conf.lo.disable_ipv6 = 1
net.ipv6.conf.enp0s3.disable_ipv6 = 1

If you check with ip a after restarting, it remains persistently.

$sudo sysctl --all | grep disable_ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.enp0s3.disable_ipv6 = 0
net.ipv6.conf.lo.disable_ipv6 = 1

solution

It doesn’t seem to work because it is managed by Network manager.
Then execute the following magic and reboot (enp0s3 should be read depending on the environment)

$sudo nmcli connection modify enp0s3 ipv6.method ignore

Now when you look at ip a, it’s disabled.

By the way

Even if you look at netstat in this state, apache etc. is displayed as LISTEN in IPv6.
More on this below.
https://qiita.com/fetaro/items/d5164ba8271114d8a0c8

reference

https://linuxhint.com/disable_ipv6_centos8/