Disable IPV6 in Alma Linux

Apr 2024

Introduction

By default, Alma Linux will have any IPV4 addresses that you assign, but some IPV6 ones, that maybe you did not, for cleaner management you might want to get rid of any IPV6 addresses that you do not need or did not configure.
Here is an example from a device that has both IPV4 and IPV6 Addresses, the IPV4 addresses were manually configured, and the IP V6 ones just seemed to appear.

ip -br -c a
eno1 UP
eno2 UP
eno3 UP 11.0.211.3/16 fe80::76fe:48ff:fe57:6c7a/64
eno4 UP 12.0.211.4/16 fe80::76fe:48ff:fe57:6c7b/64
eno5 DOWN
eno6 UP 10.0.211.6/16 fe80::76fe:48ff:fe57:6c7d/64
mngt UP 192.168.1.211/24 fe80::ec4:7aff:fed9:9f6a/64
flannel.1 UNKNOWN 10.42.0.0/32 fe80::e82c:7bff:fe8c:132a/64
cni0 UP 10.42.0.1/24 fe80::d02e:25ff:feb6:5865/64

IPV6 Address Removal

The title is a bit misleading, we are just going to disable some IPV6 settings, the addresses will go on their own.
From SSH, Edit the file /etc/sysctl.conf by default it will likely just contain the following:

# sysctl settings are defined through files in
# /usr/lib/sysctl.d/, /run/sysctl.d/, and /etc/sysctl.d/.
#
# Vendors settings live in /usr/lib/sysctl.d/.
# To override a whole file, create a new file with the same in
# /etc/sysctl.d/ and put new settings there. To override
# only specific settings, add a file with a lexically later
# name in /etc/sysctl.d/ and put new settings there.
#
# For more information, see sysctl.conf(5) and sysctl.d(5).

At the end of this file, add the following lines (you may not need all of them, or you may need more) replacing the interface names with your own.

net.ipv6.conf.eno1.disable_ipv6 = 1
net.ipv6.conf.eno2.disable_ipv6 = 1
net.ipv6.conf.eno3.disable_ipv6 = 1
net.ipv6.conf.eno4.disable_ipv6 = 1
net.ipv6.conf.mngt.disable_ipv6 = 1

Save the file. Next we need to edit the ifcfg-enox files in /etc/sysconfig/network-scripts.
In each file add the following 2 lines

IPV6INIT=no
IPV6_AUTOCONF=no

Once all the changes have been made, reboot the server.