How to Disable IPv6 on Linux

IPv6 is the next-generation internet protocol, designed to replace the current Internet Protocol, IP Version 4. IP addresses are required for communication between two devices. It is an identity of a computer over Internet.

This article will help you to disable IPv6 from your Linux box.

1. Check IPv6 Address

Use ifconfig command to view current IPv6 address on your system. You will get results something like below.

[[email protected] ~]# ifconfig 

eth0: flags=4163  mtu 1500
        inet 45.55.65.94  netmask 255.255.224.0  broadcast 45.55.95.255
        inet6 fe80::601:92ff:fe35:ea01  prefixlen 64  scopeid 0x20<link>
        ether 04:01:92:35:ea:01  txqueuelen 1000  (Ethernet)
        RX packets 2411381  bytes 794420295 (757.6 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2151232  bytes 351005391 (334.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth1: flags=4163  mtu 1500
        inet6 fe80::601:92ff:fe35:ea02  prefixlen 64  scopeid 0x20<link>
        ether 04:01:92:35:ea:02  txqueuelen 1000  (Ethernet)
        RX packets 8  bytes 648 (648.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 123828  bytes 21997128 (20.9 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 0  (Local Loopback)
        RX packets 47584  bytes 4822673 (4.5 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 47584  bytes 4822673 (4.5 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

2. Disable IPv6 Temporarily

If to disable IPv6 for your current session, Simply use following command to set run time variable. Remember that below change will be discards after system reboot.

$ sudo echo "1" > /proc/sys/net/ipv6/conf/all/disable_ipv6

3. Disable IPv6 Permanent

To disable IPv6 permanently, edit /etc/sysctl.conf file and add/update following parameters

$ vi /etc/sysctl.conf

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

and reload sysctl configuration using following command

$ sudo sysctl -p