dhcpcd-discuss

Hey,

I have a set up at home with one host sending ICMPv6 router advertisements
to configure my internal IPv6 network (and actually also doing DHCPv6, but
this is irrelevant for the issue at hand I believe). However, I don't have
a public IPv6 address, so I just want IPv6 on my internal network, while
still configuring a custom prefix (in the fd00::/8 range) and properly
configuring DNS information. Everything seems to work, but the host sending
the RAs becomes the default gateway for every other host on the network.
That default route is bogus, since the host in question doesn't have a
public IPv6 address. I just want IPv6 on my internal network.

So, I read some more, and it would seem that setting the router lifetime
field of the RA to 0 should do exactly what I want: prevent the host from
becoming a default route. RFC4861 says:

> The lifetime associated with the default router in units of seconds.  The
> field can contain values up to 65535 and receivers should handle any value,
> while the sending rules in Section 6 limit the lifetime to 9000 seconds.  A
> Lifetime of 0 indicates that the router is not a default router and SHOULD
> NOT appear on the default router list. The Router Lifetime applies only to
> the router's usefulness as a default router; it does not apply to
> information contained in other message fields or options.  Options that
> need time limits for their information include their own lifetime fields.


However, when I set that field to zero, dhcpcd doesn't seem to process the
RA at all and ignores all information, including prefix and dns
information. If I understand the RFC correctly, this behavior is wrong and
the prefix and dns (and other) information should still be processed. For
the moment I "worked around it" by setting the lifetime to 1, meaning the
route becomes invalid after one second. However, the route does stay in the
routing table for one second, so it's quite an ugly workaround.

Kind regards,
Maarten de Vries