[GLLUG] RADVD configuration

Chris Bell chrisbell at chrisbell.org.uk
Wed Apr 5 16:20:45 UTC 2017

On Wednesday 05 Apr 2017 12:32:15 you wrote:
> Hi,
> Think of the Global address as the one used between hosts (e.g. interface
> eth0), and the site local as the loopback (e.g. interface lo). (i.e. not
> route-able outside of the host)
> Kind Regards
> James
Thanks for the reply. There is sparse documentation for RADVD, so I have been 
ploughing through well over 100 RFC's trying to find information. An interface 
can have more than one IPv6 address, in theory as many as you wish. The fexx:: 
series of address prefixes are available for site local use as specified in the 
RFC's, and I am trying to use one site-local prefix for each of the local 
networks, (I am required to generate a genuine random number for bits 9 to 56, 
and they have the same initial 62 bits with only bits 63 and 64 changed), to 
be used for site local connections only, and in addition all can eventually 
share the same allocated global prefix. 
According to the RFC's each network interface should receive the full 
information from RADVD and then choose the correct prefix to match the route. 
The shorewall6 interfaces should each have both a site local address prefix and 
the global allocated address prefix. I have not seen anything to suggest that 
the suffix for each address should be the same on any individual interface, 
there could be an automatically generated suffix based on the MAC as well as one 
or more manually configured. The fun thing is to persuade shorewall, 
shorewall6, rdnss, dnssl, abro, and radvd to actually run, and then work 
together, with a laborious time-consuming process of trying another 
configuration amendment, reading the error messages, and so on.
It is not really necessary for my home network, but I think it is supposed to 

Chris Bell
website chrisbell.org.uk

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