On OS X 10.9 I don't have a way to disable IPv6 that I can find. In Network > Advanced > TCP/IP > Configure IPv6, there are only three choices: automatic, manual, link local. And as soon as I configure it with either manual or link local, the wifi connection changes from green to yellow and I no longer have even IPv4 Internet, although it remains identically configured as before. A while ago this popup had an Off option just like the Configure IPv4 menu does.
Doesn't work that way for me. On 10.9.5 setting the wifi connection's IPv6 setting to "Link-local only" causes me to be unable to ping6 other machines but IPv4 is unaffected.
