How to disable IPv6 in CentOS 7

Recently, a friend of mine asked me how to disable IPv6. After searching for a few, I found the following scenario. Here's how to turn off IPv6 on my CentOS 7 mini-server.

You can do this in two ways.

Method 1

Edit File /etc/sysctl.conf,

1. VI /etc/sysctl. conf

Add the following line:

1. NET. IPv6. Conf. All. Disable_ipv6 =1
2. NET. IPv6. Conf. Default. Disable_ipv6 =1

If you want to disable IPV6 for a particular NIC, for example, for ENP0S3, add the following line.

1. NET. IPv6. Conf. Enp0s3. Disable_ipv6 =1

Save and exit the file.

Execute the following command to make the setting effective.

1. Sysctl -p

Method 2

To disable IPV6 in a running system, enter the following command:

1. echo 1>/proc/sys/net/ipv6/conf/all/Disable_ IPv6
2. echo 1>/proc/sys/net/ipv6/conf/default/ Disable_ipv6

Or

1. Sysctl -w net. IPv6. Conf. All. Disable_ipv6=1
2. Sysctl -w net. IPv6. Conf. Default. Disable_ipv6=1

That's it. Now the IPV6 has been banned.

What do I do if I have problems after banning IPv6?

You may have some problems after banning IPv6.

Question 1:

If you are having problems with SSH after you disable IPV6, follow the instructions below.

Edit /etc/ssh/sshd_config file

Vi/etc/ssh/sshd_config

Locate the following line:

1. #AddressFamily any

Change it to:

1. AddressFamily inet

Or, remove the comment (#)in front of the line:

1. #ListenAddress 0.0.0.0

Then restart SSH for the change to take effect.

1. Systemctl Restart sshd

Question 2:

If you are having trouble starting postfix after you disable Ipv6, edit /etc/postfix/main.cf:

1. VI /etc/postfix/main. CF

Comment out the localhost part of the configuration and use the IPv4 loopback.

1. #inet_interfaces = localhost
2. Inet_interfaces =127.0. 0.1

How to disable IPv6 in CentOS 7