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Help needed setting up IPv6 Privacy Extension

1275 Views 11 Replies Latest reply: Jul 27, 2012 7:47 AM by cute crow RSS
cute crow Level 1 Level 1 (35 points)
Currently Being Moderated
Jul 6, 2012 3:30 PM



Some time ago I thought I had enabled Privacy Extensions (aka Privacy Address) for IPv6 on my Snow Leopard mac.


If I use the ifconfig command, after inet6 it lists what looks like an IPv6 address and it has most of my MAC address in it.


So I'm guessing that I haven't set Privacy Extensions up correctly.


Is there any one who could help me?


To enable Privacy Extensions I used nano to create a file called sysctl.conf in /etc/ and in that file using nano I wrote the following:



Looking back I think that I may have omitted a key part. According to it cryptically says  to enable privacy extensions:

sysctl -w net.inet6.ip6.use_tempaddr=1


Should I have included the sysctl -w part in my nano edit of my sysctl.conf ?


(And as you'll have gathered I'm not particularly proficient with Terminal or Unix etc)

  • Linc Davis Level 10 Level 10 (107,995 points)
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    Jul 6, 2012 6:53 PM (in response to cute crow)

    I haven't tried recently, but the last time I checked, sysctl.conf was ignored, even though the sysctl man page says it shouldn't be. If that hasn't changed, you'd have to create a launchd job to run sysctl commands automatically at startup.

  • g_wolfman Level 4 Level 4 (1,110 points)
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    Jul 7, 2012 9:01 AM (in response to cute crow)

    ifconfig may very well be displaying the "default canonical" modified EUI-64 address derived from the MAC address by stateless autoconfiguration.


    It may also not be the IPv6 address being used on your network (assuming you even have an IPv6 address on your network).  You may get better results seeing what is actually being used with:


    networksetup -getinfo Wi-Fi (or -getinfo Ethernet - depending or how you are connected).

  • g_wolfman Level 4 Level 4 (1,110 points)
    Currently Being Moderated
    Jul 7, 2012 1:29 PM (in response to cute crow)

    networksetup -listallnetworkservices


    Will give you the names of all the services (it will be the same as those listed in the Network System Preference sidebar).  Wi-Fi is the default name for WLAN networking on my MBP; perhaps Airport is the default name on an iMac.


    The easiest way to see your addresses is via the Network System Preference pane.  If you aren't on IPv6, then no information will be displayed beyond the "Configure" drop-down - very similar to the IPv4 section.


    As for ifconfig, it generally shows some combination of the following:


    Interface Name (lo0, en0, en1, p2p0, etc);

    Flags associated with the interface and the MTU (max number of bytes in a frame on the interface);

    Options associated with the interface (if there are any);

    The ethernet (MAC) address or link-local (lladdr) address of the interface (if there is one, not all interfaces have a hardware address);

    The inet6 (IPv6) and inet (IPv4) addresses;

    Various other infor; and,

    An "active" or "inactive" indicator.


    It's often just easier to open the System Preferences application and use the Network preference pane...also, since that is a GUI frontend to the networksetup program, it's closer to the actual utility OS X uses to manage it's interfaces.

  • g_wolfman Level 4 Level 4 (1,110 points)
    Currently Being Moderated
    Jul 11, 2012 7:00 AM (in response to cute crow)

    Link-local addresses are assigned using stateless autoconfiguration, so that explains the EUI-64 address derived from your MAC address.


    As for your earlier question, until and unless you are actually on an IPv6 network, I don't think you'll be able to determine your IPv6 address exactly, because you won't have one until then.


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