[HECnet] Connections?

[Johnny Billquist]

On 2018-05-04 02:41, dwe-6006 at philtest.org wrote:
> IP flows and connections are identified by the 5-tupple of protocol, source address, source port, destination address, and destination port which at any point in time is guaranteed to uniquely identify the connection.

Not really correct, but close enough in this case.
For TCP, it's a four tuple. Which, if you include the protocol then 
makes it a five tuple. However, this is only true for TCP. UDP is 
different, and your connection is actually just identified by the local 
port. The same connection is used for all UDP communication on that 
local port on that machine. But there one local port can communicate 
with multiple remote ends, and you can also do broadcasts. And UDP don't 
really have a concept of a connection.

IP in itself only identifies things by local address and protocol. 
Depending on the protocol, you might then have different additional 
information and multiplexing on top of that. But exactly how that 
appears depends on the protocol.
There are essentially no fixed view on how a connection is identified, 
or what even consist a connection.

   Johnny

> 
> --Dave
> 
> -----Original Message-----
> From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Johnny Billquist
> Sent: Thursday, May 3, 2018 7:21 PM
> To: bob at jfcl.com; hecnet at Update.UU.SE
> Subject: Re: [HECnet] Connections?
> 
> On 2018-05-04 00:00, Robert Armstrong wrote:
>>> In RSX, you can have any number of
>>> listeners on one specific port,
>>
>>     The Multinet tunnel software emulates a point to point circuit, like a DDCMP synchronous link only with TCP/IP.  In theory the only traffic that goes down that link should be messages addressed to the node on the other end (or any node that it's the next hop for).
>>
>>     If you accept multiple connections on the same port, how do you know who is on the other end?  I don't remember anything in the Multinet protocol to identify the nodes.  If you don't know who is on the other end, how do you know what traffic to send him??
> 
> It's TCP. It's always point to point. There are no broadcast ability in TCP. However, there is nothing preventing you to have multiple TCP connections with the same local port. It's still separate connections.
> 
> Maybe we're talking past each other here?
> 
> It is very common that you have a service that listens to a port, and which accepts multiple connections. Think http for example. Multinet is no different.
> 
>     Johnny
> 


-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol