[HECnet] Intermittent Connection with PyDECnet?

[Johnny Billquist]

On 2020-03-02 20:26, Paul Koning wrote:
> 
> 
>> On Mar 2, 2020, at 1:56 PM, Robert Armstrong <bob at jfcl.com> wrote:
>>
>>> First of all, unless PyDECnet is somewhat limited, it should be fine
>>> using the standard Multinet port for all incoming connections
>>
>>   I don't see how you can have multiple Multinet TCP connections all listening on port 700 at the same time.  Yes, you can have multiple outgoing connections all to port 700 on some remote machine, but that's not the same.  And for UDP it's no problem for everybody to share the same port, but again that's not the same.
>>
>> Bob
> 
> PyDECnet right now has a listening port per circuit, and allows one connection on that (of course, since circuits are point to point).  The "any address allowed" case just means that at connect time the connection will not have its remote address checked.
> 
> That said, as Johnny points out, it's certainly possible to have a design where a listener socket accepts several connections, associating those with several circuits.  That would translate into "multiple connections to a given listener port".  By TCP rules, connections are identified by a "five-tuple" (source and dest IP address, IP protcocol, and source and dest port numbers).  So that all works.
> 
> I could have PyDECnet feed connections into a pool of circuits, or have circuits created on the fly up to some limit, but neither of these options is in the current design.

Right. In RSX, I just grab the first "free" circuit in the pool assigned 
to that port.

> Going back to the security discussion, I think "node verification" (the password exchange that optionally happens at the point to point initialization handshake in DECnet) would be adequate.  All the DEC products have this in one way or another, as does PyDECnet (though the documentation is not really there, I should fix that).  The one complication is that while the protocol is standardized, the management of it isn't, so each DECnet has its own way of doing it.

Yeah. And this is where I'm not at all happy with RSX. Because the node 
verification in RSX is set on the whole system, and not per circuit.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
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