I played with temporary IPv6 addresses r ... / 2009-11-18

I played with temporary IPv6 addresses recently, the privacy extension where the right half of the address isn't always the same address derived from the ethernet mac address but a random address. I noticed when I set Linux to use the temporary address as preferred address it was listed as 'secondary':

# ip -6 addr ls
1: lo:  mtu 16436 
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
22: wlan0:  mtu 1500 qlen 1000
    inet6 2001:888:1011:1:10f3:2799:3587:237e/64 scope global secondary dynamic 
       valid_lft 604544sec preferred_lft 85544sec
    inet6 2001:888:1011:1:21f:e1ff:fe45:2894/64 scope global dynamic 
       valid_lft 2591744sec preferred_lft 604544sec
    inet6 fe80::21f:e1ff:fe45:2894/64 scope link 
       valid_lft forever preferred_lft forever

I thought maybe I can use this to fix my outgoing IPv6 address selection problem. Searching for clues how to change the status of an IPv6 address using the ip command I found: IPv6 Source Address Selection on Linux which answers my question completely, and now I can 'block' the tunnel address completely for outgoing connections:

# ip -6 addr ls dev xs4allipv6
7: xs4allipv6@NONE:  mtu 1480 
    inet6 2001:888:1011::13/128 scope global 
       valid_lft forever preferred_lft forever
    inet6 2001:888:10:11::2/64 scope global deprecated 
       valid_lft forever preferred_lft forever
    inet6 fe80::a2a:1401/64 scope link 
       valid_lft forever preferred_lft forever
    inet6 fe80::525f:c4ca/64 scope link 
       valid_lft forever preferred_lft forever
    inet6 fe80::a2a:201/64 scope link 
       valid_lft forever preferred_lft forever

The tunnel address is 'deprecated' so it will not be used for outgoing connections but the system still responds to it so routing works. Now the wanted address is chosen when I connect to a system 'nearby' in IPv6 address terms:

tcp6       0      0 2001:888:1011::13:41041 2001:888:0:311:194::119 ESTABLISHED