[nos-bbs] Presence of IPV6 on tun interface & random JNOS crashes ?

[Chris Maness]

Another tip on possible crashes is having a netrom packet allowed
longer than 236.  I had mine set at 256, and it was crashing
constantly, changed it to 236 and it has not happened since.  This is
obviously purely anecdotal, but I have good reason to believe that
this is the reason for the netrom crashes coincidence notwithstanding.

-Chris KQ6UP

On Wed, Feb 1, 2023 at 5:24 AM Maiko (Personal) <maiko at pcsinternet.ca> wrote:
>
> There is a small chance that if you have IPV6 enabled, JNOS will
> receive IPV6 packets over the tun interface, even if you have no
> desire to run IPV6, I noticed in my trace when I enabled IPV6 on
> my linux host system. Suddenly started seeing odd warnings, ie :
>
> Tue Jan 31 19:15:52 2023 - tun1 recv:
> IP: bad header
> 0000  60 09 0f 93 00 28 06 40 fd 00 00 04 00 00 00 00  `....(.@}.......
> 0010  00 00 00 00 00 00 00 01 fd 00 00 04 00 00 00 00  ........}.......
> 0020  00 00 00 00 00 00 00 02 97 22 00 17 d5 a9 df 4a  ........."..U)_J
> 0030  00 00 00 00 a0 02 fd 20 b9 38 00 00 02 04 05 a0  .... .} 98.....
> 0040  04 02 08 0a 0c 59 3f 27 00 00 00 00 01 03 03 07  .....Y?'........
>
> The reason I suggest it 'might' be contributing to random crashes is
> that the IP version is only checked after IP header extraction, which
> means it had to parse data it was not meant to receive to find out the
> type of data. Chances are probably it's not a big deal, but perhaps it
> is something to rule out for those having random crash issues.
>
> IF you can disable ipv6 on the tun interface between linux host and JNOS
> itself, then see if that helps. I'll leave it up to you to figure out.
>
> Maiko / VE4KLM
>
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-- 
Thanks,
Chris Maness