Re: OpenVPN suddenly working one way only

> On 7/5/24 16:32, Rodney W. Grimes wrote:
> 
> >> However, I just changed UDP port and it seems to work!
> 
> The "solution" didn't last: after a little more than 3 hours, this 
> tunnel stopped working again :(
> 
> Strangely restarting openvpn on both sides fixed this, this time.
> 
> 
> 
> 
> > Or host A has a zombie process with a UDP listen on the port?
> 
> It's host B listening as a server: host A connects to it.
> So I guess I should look into host B...

Host A *still* has/had a port open, and that port can lingere
for several reasons, and that can cause issues.

It can also happen on Host B, but we always look there, right?
What I am getting at is you shouldnt assume the problem could
not be on the orignating(client) end.

> 
> And no, "netstat -na" show no udp4 line with the choosen port, after I 
> stop openvpn.

Ok, good, check both A and B.

> 
> To my ignorance, this reminds me of the "no buffer space available" I 
> sometimes get with ping.

Thats usually a stuffed up tunnel that can't transmit for some reason.
ppp will do this if it things the link is down for any reason.

> That's just a wild guess, of course, but I suspect something is wrong 
> with UDP on the "server" host...

MTU's?  Have you manually checked path MTU to make sure that it
can carry your payload correctly IN BOTH DIRECTIONS.  I have
seen asymetrical routes cause MTU issues due to it being smaller
in one direction.

>   bye & Thanks
> 	av.
-- 
Rod Grimes                                                 rgrimes@freebsd.org