Department of Defense
High Performance Computing Modernization Program

In Apple macOS (all versions) and OS X (versions 10.3 Panther through 10.11 El Capitan), Internet Protocol version 6 (IPv6) is on by default. It was also supported in OS X 10.1 Puma and OS X 10.2 Jaguar, but turned off by default.

To turn it off in OS X (versions up through 10.6 Snow Leopard), do the following:

Open the System Preferences - Network panel. Go into the properties for each network interface and click on the Advanced - TCP/IP tab. Then click the Configure IPv6 button and set the menu to Off. Click OK and then Apply Now. Close System Preferences.

If you insist on using the command line, the command to turn off IPv6 on all network interfaces is

/usr/sbin/ip6 -x

If either of the following variables are defined in /etc/sysctl.conf, delete them (no matter what value they have):



In macOS (all versions) and OS X (versions 10.7 Lion and later), the System Preferences - Network panel cannot be used. Instead, you must use the command line

networksetup -setv6off Ethernet

(or Wi-Fi or any other specific network interface you want to disable IPv6 on).