How to disable IPv6 in CentOS 7

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

You can do this in two ways.

Method 1

Edit File/etc/sysctl.conf,

Vi/etc/sysctl.conf

Add the following line:

Net.ipv6.conf.all.disable_ipv6 = 1

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.

Net.ipv6.conf.enp0s3.disable_ipv6 = 1

Save and exit the file.

Execute the following command to make the setting effective.

Sysctl-p

Method 2

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

Echo 1 >/proc/sys/net/ipv6/conf/all/disable_ipv6

Echo 1 >/proc/sys/net/ipv6/conf/default/disable_ipv6

Or

Sysctl-w net.ipv6.conf.all.disable_ipv6=1

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:

#AddressFamily any

Change it to:

AddressFamily inet

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

#ListenAddress 0.0.0.0

Then restart SSH for the change to take effect.

Systemctl Restart sshd

Question 2:

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

Vi/etc/postfix/main.cf

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

#inet_interfaces = localhost

Inet_interfaces = 127.0.0.1

That 's it . ~

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How to disable IPv6 in CentOS 7