How To Disable IPv6 on Debian 11 / 10 & Ubuntu 20.04 / 18.04
Abstract: Output of ifconfig command Before Disabling IPv6 The above output confirms that IPv6 is enabled for both network cards. Method 1 Edit the /etc/sysctl.
This post helps you in disabling ipv6 on Debian 11 / 10 & Ubuntu 20.04 / 18.04. IPv6 can be disabled by modifying sysctl.conf or by creating a .conf file in the /etc/sysctl.d directory. You can also disable IPv6 for a particular network adapter.
The steps mentioned here should work on previous versions of Debian such as Debian 9 and 8, also, Ubuntu versions such as Ubuntu 19.10, 19.04, and 18.10.
Disable IPv6 on Debian 11 & Ubuntu 20.04Before disabling the IPv6, let us see the available network cards on the system. Use the ifconfig command.
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.0.10 netmask 255.255.255.0 broadcast 192.168.0.255 inet6 2406:7400:bf:7cdd:a00:27ff:fe68:1c64 prefixlen 64 scopeid 0x0 inet6 fe80::a00:27ff:fe68:1c64 prefixlen 64 scopeid 0x20 inet6 2406:7400:bf:7cdd:882d:c9c6:df13:890 prefixlen 64 scopeid 0x0 ether 08:00:27:68:1c:64 txqueuelen 1000 (Ethernet) RX packets 1174 bytes 80087 (78.2 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 372 bytes 46400 (45.3 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 8 bytes 396 (396.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 8 bytes 396 (396.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0Output of ifconfig command Before Disabling IPv6
The above output confirms that IPv6 is enabled for both network cards.
Method 1Edit the /etc/sysctl.conf file.
sudo nano /etc/sysctl.conf
Place the following entry to disable IPv6 for all adapters.
net.ipv6.conf.all.disable_ipv6 = 1
For a particular adapter (If the network card name is enp0s3).
net.ipv6.conf.enp0s3.disable_ipv6 = 1
To reflect the changes execute the following command.
sudo sysctl -pMethod 2
Create a file called 70-disable-ipv6.conf in the /etc/sysctl.d directory.
sudo nano /etc/sysctl.d/70-disable-ipv6.conf
Add the following entry to disable IPv6 for all adapters.
net.ipv6.conf.all.disable_ipv6 = 1
For a particular adapter (If the network card name is enp0s3).
net.ipv6.conf.enp0s3.disable_ipv6 = 1
Run the below command to take an effect of changes.
sudo sysctl -p -f /etc/sysctl.d/70-disable-ipv6.confVerify IPv6
Verify that IPv6 has been disabled using the ifconfig command.
Output of ifconfig command After Disabling IPv6You can see that there is no IPv6 address in the output.
ConclusionThat’s All.