Re: How to extract IPv6 RAs?

[Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxx>]

On Sun, Aug 29, 2010 at 11:56 PM, Pavel Herrmann
<morpheus.ibis@xxxxxxxxx> wrote:
> the only solution I see (apart from specifying netmask in DHCP reply, that is)
> is to remember the prefixes (in kernel, as no userspace daemon like
> NetworkManager should be required for network configuration) and give the user
> a way to retrieve this information (like fBSD has, with "ndp -p"). DHCPv6
> client can then use this tool to get a prefix length for received address
> before setting it (eg. in dhclient-script in case of ISC dhclient).

While deploying IPv6 between some new VMs i noticed that this
information is already available in the kernel. The routing-table
should hold these prefixes flagged with RTF_ADDRCONF | RTF_PREFIX_RT.
I didn't check if these flags will be exported to user-space but i
think so. A dhcpv6-client should scan the routing-table for prefixes
with these flags set and apply the specified prefix-length to the
announced ip-address. There should also be an event fired if these
prefixes will time out.

  hannes
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