Disable IPv6 on Debian 12

Step 1: Edit sysctl.conf

Open /etc/sysctl.conf in a text editor:

nano /etc/sysctl.conf

Scroll to the bottom of the file and add:

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

Step 2: Apply the changes

Reload sysctl values:

sysctl -p

Step 3: Verify IPv6 is disabled

ip a | grep inet6

If nothing shows up, IPv6 has been disabled successfully ✅