Subj : Re: Help?
To   : Markus Reschke
From : Nicholas Boel
Date : Wed Feb 25 2015 17:14:38

Hello Markus,

On 25 Feb 15 11:39, Markus Reschke wrote to Nicholas Boel:

 NB>> I have no idea how in the world I'm getting (or originally got)
 NB>> the other v6 address, nor have I or do I want it whatsoever. Is
 NB>> there a safe way to remove that address (the one ending in 6954)
 NB>> permanently?

 MR> Please run the following cmd to check if privacy extensions are
 MR> enabled:

 MR> cat /proc/sys/net/ipv6/conf/eth0/use_tempaddr

 MR> (replace eth0 with the interface used)

$ cat /proc/sys/net/ipv6/conf/all/use_tempaddr
0
$ cat /proc/sys/net/ipv6/conf/default/use_tempaddr
0
$ cat /proc/sys/net/ipv6/conf/enp2s6/use_tempaddr
0

 MR>         Preference for Privacy Extensions (RFC3041).
 MR>           <= 0 : disable Privacy Extensions
 MR>           == 1 : enable Privacy Extensions, but prefer public
 MR>                  addresses over temporary addresses.
 >>  1 : enable Privacy Extensions and prefer temporary
 MR>                  addresses over public addresses.

So according to the above, I shouldn't have two addresses, right?

 NB>> If not, I assume I'll have to setup a static address (maybe with
 NB>> privacy extensions enabled in order to not have to use my MAC
 NB>> address) and disable any dynamic addresses? In this case, anyone
 NB>> have any good links with detailed instructions on how to do so,
 NB>> so I don't screw things up worse than they are?

 MR> When you enable PE you'll get two addresses for each prefix. The first
 MR> one is the automatic one based on the MAC. And the second one is the
 MR> random one. There are also some timers which can be adjusted to
 MR> optimize the handling of the address changes.

This is where the problem lies. I don't have PE enabled, so I shouldn't have two addresses. And you also mention that the first one is the automatic based on the MAC, whereas it seems as though my two are backwards!

$ ifconfig
enp2s6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.100  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 2001:470:1f11:1027:68d4:530a:2845:6954  prefixlen 64  scopeid 0x0<global>
        inet6 2001:470:1f11:1027:207:e9ff:fe49:6711  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::207:e9ff:fe49:6711  prefixlen 64  scopeid 0x20<link>
        ether 00:07:e9:49:67:11  txqueuelen 1000  (Ethernet)
        RX packets 104084  bytes 36164060 (34.4 MiB)
        RX errors 0  dropped 8  overruns 0  frame 0
        TX packets 95715  bytes 25845065 (24.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Notice my link local address as well as my ethernet MAC match the second one, not the first! :(

Regards,
Nick

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