Re: connection loss related to ndp?

> On 22 May 2023, at 00:34, Bjoern A. Zeeb <bzeeb-lists@lists.zabbadoz.net> wrote:
> 
> Hi,
Hi Bjoern,
> 
> I am on 14-CUREENT (6fa88a4ad35e from April) and I recently started to
Could you please check if that’s a local commit? I’m not able to find this one in -main.
> experience something which looks like:
> 
> ping6 -n ff02::1%wlan0 works
> ping6 -n host works
Is ‘host’ a global unicast address reachable via the default route?
> 
> but ssh to host hangs.  Given this seemed to be periodic-ish and I only
> always notice way after the facts I started to poke around and found:
> 
> ndp -P
> ndp -R
> rtsol wlan0
> 
> fixes things.
> 
> 
> I've seen similar problems with NDP vs. routing table updates and
> another rtsol call would not bring back the default route unless
> ndp -R was run before and I wonder if these are connected.
> 
> Both have become a bit annoying problems on a day-to-day IPv6-only usage
> for me that I had never experienced like this (in the last decade) before.
> 
> If anyone has ideas and saves me from spending too many hours digging
> into this now I'd appreciate.
There were a number of changes related to routing/ndp (by me) and PCB table split work, so there are multiple candidates for the issue.
I’d start with checking with tcpdump (w/o promisc) output when running ssh. Specifically, checking if
* SYN is sent to the right destination with the right source address
* Destination MAC is correct
* S+A Is received
I’d also check if NDP record for the default GW looks sane & check the PCB status while SSH is trying to connect.

> 
> /bz
> 
> -- 
> Bjoern A. Zeeb                                                     r15:7
>