[arch-general] No ipv6 address - but only on one machine

Giancarlo Razzolini grazzolini at archlinux.org
Fri Dec 22 17:43:07 UTC 2017

Em dezembro 22, 2017 14:15 David Rosenstrauch escreveu:
> 1) Wifi router reports an IPv6 address on both the WAN and the LAN 
> sides.  (In the 2607: range.)

That's a global address range, for sure.

> 2) Mac desktop behind the router successfully gets assigned an ipv6 
> address.
> 3) Linux laptop (running Arch) successfully gets assigned an ipv6 
> address (using NetworkManager).
> 4) Linux server (also running Arch) does not get assigned an ipv6 
> address.
> The server is using netctl for networking, and its profile includes:
> ## For IPv6 autoconfiguration
> IP6=stateless

Try using stateful here.

> Yet for some reason, this machine doesn't get assigned an external ipv6. 
>   Rather it only gets assigned one in the link-local range.  (I.e., in 
> the fe80: range.)

Link-local addresses are assigned to any interface when they are created,
regardless of other IPv6 configuration.

> I have to admit this is pretty puzzling.  I can't for the life of me 
> figure out why the server can't get an address.  Particular since it was 
> able to do so successfully probably about a week or so ago.
> Anyone have an idea what could have happened here?  Has there been some 
> package update recently that might explain this?  Or any pointers on how 
> I might go about debugging this?

Well, stateless configuration, or SLAAC, relies heavily on ICMPv6 and NDP.
A firewall can block these. If you try to use stateful configuration and it
works, then you might be inadvertently be blocking the packets used on slaac.

Giancarlo Razzolini
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