Re: Debian 12 IPv6 client?
On Tue 14 Mar 2023 at 15:00:20 (+0800), Jeremy Ardley wrote:
> 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.
I get my link address without any configuration by me: nothing like
iface enp0s3 inet6 auto is involved. So that line, unfamiliar to
me as a bullseye user, may be the cause of your routable address
problem. What happens if you take it out?
Cheers,
David.
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