CentOS 7 Forbidden IPv6

How to disable IPv6 in CentOS 7

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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.

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

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/< Span class= "PLN" style= "color: #b8ffb8" >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.

You may have some problems after banning IPv6.

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

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, cheers!

CentOS 7 Forbidden IPv6