[GLLUG] Using IPv6 addresses with Debian

Chris Bell chrisbell at chrisbell.org.uk
Fri Mar 12 10:58:15 UTC 2021

On Friday, 12 March 2021 10:15:04 GMT John Winters via GLLUG wrote:
> On 11/03/2021 15:14, Chris Bell via GLLUG wrote:
> > Hello,
> > IPv6 is designed so that a single address can be allocated to multiple
> > interfaces, for example in a round-robin, and a single interface can have
> > multiple addresses.
> > I am using Debian 10 Buster on various computers including RaspberryPi and
> > find that I can manually add addresses to a running computer, but if I
> > attempt to configure multiple addresses only the last is accepted, and
> > all but one is lost after a reboot.
> I've found various ways of configuring additional IPv6 addresses on
> Raspbian / Debian Buster.  It depends to a large extent on whether it's
> headless or using a graphical desktop - where there are desktop client
> components which want to get involved.
> On a plain (headless) Raspbian system, what I did was to edit
> /etc/dhcpcd.conf and added the following two lines at the end:
> interface eth0
> static ip6_address=2001:<more of it>:4001/64
> That causes dhcpcd to allocate that one in addition to the one it
> calculates from the MAC address.
> On another headless Raspberry Pi, but running plain Debian Buster (not
> Raspbian) I put the following in /etc/network/interfaces.d/eth0
> auto eth0
> allow-hotplug eth0
> iface eth0 inet dhcp
> iface eth0 inet6 static
> 	address 2001:<the rest>
> 	netmask 64
> This causes the interface to be configured with *just* that IPv6 address
> (no auto-calculated one) but you can always put additional ones there too.
> I suppose it depends on whether you're running dhcpcd or not.  Raspbian
> does by default, but Debian doesn't.
> John

Thanks for the suggestion, which I will try, but I have had problems with even 
dhcpcd.conf on a raspberrypi. Systemd instructions go into great detail, but 
it still does not enable more than one IPv6 address per interface. I hope that 
debian 11 Bullseye will work.

Chris Bell
Website http://chrisbell.org.uk

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