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Groups > linux.debian.user > #256017

Re: Debian 12 IPv6 client?

From Jeremy Ardley <jeremy@ardley.org>
Newsgroups linux.debian.user
Subject Re: Debian 12 IPv6 client?
Date 2023-03-14 08:10 +0100
Message-ID <G96Xf-cncx-9@gated-at.bofh.it> (permalink)
References <G94sp-clpm-1@gated-at.bofh.it> <G95eN-clX3-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 14/3/23 13:15, David Wright wrote:
>
>> cat /etc.network/interfaces
>> # This file describes the network interfaces available on your system
>> # and how to activate them. For more information, see interfaces(5).
>>
>> source /etc/network/interfaces.d/*
>>
>> # The loopback network interface
>> auto lo
>> iface lo inet loopback
>>
>> # The primary network interface
>> allow-hotplug enp0s3
>> iface enp0s3 inet dhcp
>> # This is an autoconfigured IPv6 interface
>> iface enp0s3 inet6 auto
>                 ↑↑↑↑↑↑↑↑↑↑
>
> I'm not very familiar with interfaces nowadays, but that looks
> as if it's asking for enp0s3 to be autoconfigured with an IPv6
> address. I thought that one got an IPv6 link address autoconfigured
> anyway—I certainly do.
>
> Did the debian-installer write that line (and comment)?

Yes. It was a result of the installation process identifying the 
interface and generating the necessary /etc/network/interfaces

> What's the output from:
>
>    $ ip a
>
> Mine (skipping lo):
>
>    2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
>        link/ether a4:01:23:45:67:89 brd ff:ff:ff:ff:ff:ff
>        inet 192.168.1.14/24 brd 192.168.1.255 scope global dynamic enp3s0
>           valid_lft 74247sec preferred_lft 74247sec
>        inet6 fe80::a601:23ff:fe45:6789/64 scope link      ← this here
>           valid_lft forever preferred_lft forever
>
root@debian12:/etc/network# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
group default qlen 1000
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
        valid_lft forever preferred_lft forever
     inet6 ::1/128 scope host
        valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel 
state UP group default qlen 1000
     link/ether 08:00:27:18:b6:ac brd ff:ff:ff:ff:ff:ff
     inet 10.31.40.166/24 brd 10.31.40.255 scope global dynamic enp0s3
        valid_lft 76395sec preferred_lft 76395sec
     inet6 2403:5800:c101:b700:a00:27ff:fe18:b6ac/64 scope global 
dynamic mngtmpaddr
        valid_lft 6277sec preferred_lft 2676sec
     inet6 fe80::a00:27ff:fe18:b6ac/64 scope link
        valid_lft forever preferred_lft forever

The difference to yours is  I have a routable IPv6 address in addition 
to the local link.

Your  one has  an autogenerated address

inet6 fe80::a601:23ff:fe45:6789/64

This is made as a function of your ethernet interface MAC address

I have an autogenerated address

inet6 fe80::a00:27ff:fe18:b6ac/64

and an address that must have been created as  a result of an RA or DHCP 
message as it is prefixed with my IPv6 address range

inet6 2403:5800:c101:b700:a00:27ff:fe18:b6ac/64

I note my two address  have the same tails so I guess my routable IPv6 
address is generated from the interface MAC address

I conclude there is no IPv6 DHCP involved but there must be something 
that listens to RA announcements and generates a MAC derived address 
from that.

I still need to know how to control that as there are options relating 
to privacy that can do things like generate an expendable address in a 
different way and later generate another and deprecate earlier addresses.

-- 
Jeremy
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Thread

Debian 12 IPv6 client? jeremy ardley <jeremy@ardley.org> - 2023-03-14 05:30 +0100
  Re: Debian 12 IPv6 client? Jeremy Ardley <jeremy@ardley.org> - 2023-03-14 06:10 +0100
  Re: Debian 12 IPv6 client? David Wright <deblis@lionunicorn.co.uk> - 2023-03-14 06:20 +0100
    Re: Debian 12 IPv6 client? Jeremy Ardley <jeremy@ardley.org> - 2023-03-14 08:10 +0100
      Re: Debian 12 IPv6 client? jeremy ardley <jeremy@ardley.org> - 2023-03-14 10:10 +0100
        Re: Debian 12 IPv6 client? David Wright <deblis@lionunicorn.co.uk> - 2023-03-14 19:00 +0100
          Re: Debian 12 IPv6 client? Jeremy Ardley <jeremy@ardley.org> - 2023-03-14 23:00 +0100
      Re: Debian 12 IPv6 client? David Wright <deblis@lionunicorn.co.uk> - 2023-03-14 19:00 +0100
  Re: Debian 12 IPv6 client? Charles Curley <charlescurley@charlescurley.com> - 2023-03-14 14:30 +0100

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