Re: LPR over SSH

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

John,

You understand that there are two IP addresses and two ports on every 
connection, right?  Not just one as you seem to be implying?  Every 
packet has a source address & source port, as well as a destination 
address and destination port.  You rarely hear people talk about the 
"source port", as it's usually managed by the OS and will vary with each 
connection.

But, basically, in TCP it creates a "tuple". 
SrcAddr/SrcPort/DestAddr/DestPort.   I believe there's also some sort of 
TCP sequence number involved as well.  These things are used to identify 
a specific TCP session in the TCP/IP stack of your operating system.

I don't know if SSH uses a separate TCP session for everything, or if it 
multiplexes within one.  If it multiplexes, then it doubtless includes 
it's own fields for this as well.

At any rate, I know that it works... I don't need to fully understand 
the mechanism! :)


jmmckee wrote:
> Hi Scott,
>
> Thank you for the clarification.  My confusion comes from thinking
> that the packets would need to be separated, either by adifferent IP
> address, port, or both.  If an sftp session is initiated on the i to
> the remote location, on the default port, how is an additional
> session created, on the default port, when the IP addresses on both
> ends are the same, and yet the packets get routed to the appropriate
> connection?  I thought the connection was the port.  If I understand
> the process correctly, in addition to ip address and port, there is
> also a connection number?
>
> John McKee