[PATCH]: The 6to4 stf0 interface flapping in/out of tentative in FreeBSD 11

[Andrey V. Elsukov]

On 22.06.2018 19:38, Viktor Dukhovni wrote:
> I just upgraded to 11.1-p10, forgetting I had patched my kernel,
> and the stf0 interface flapping was back, with IPv6 connectivity
> disappearing every other second or so (interface shows as "tentative"
> and outgoing connections fail with "can't assign requested address").
> 
> Appied the same patch and rebooted, and the problem is gone.  Here's
> the patch again:
> 
> Index: sys/net/if_stf.c
> --- sys/net/if_stf.c	(revision 333375)
> +++ sys/net/if_stf.c	(working copy)
> @@ -722,6 +722,7 @@
>  		}
>  
>  		ifp->if_flags |= IFF_UP;
> +		ifp->if_drv_flags |= IFF_DRV_RUNNING;
>  		break;
>  
>  	case SIOCADDMULTI:
> 
Hi,

Your change looks reasonable due to IPv6 DAD procedure does check for
presence of IFF_DRV_RUNNING flag. But actually it seems the right
solution should be disabling DAD for if_stf(4) interface.
IPv6 DAD requires that given interface should be multicast capable, but
for if_stf(4) it is not true.
Will it help if you use `ifconfig stf0 inet6 no_dad` before assigning
IPv6 address?

-- 
WBR, Andrey V. Elsukov

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