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Re: [OCLUG-Tech] Re TCP Ports -- and the little guy listening

Shawn Corey wrote:
On Thursday, July 28, 2005, at 02:34  am, S. Zachariah Sprackett wrote:

While some protocols do this, this is not necessary.  SMTP transactions,
for example can take exceedingly long times to complete.  SSH is also
often used for extended sessions.  The communication all happens on a
well known destination port (ie: 25 or 22).  It's really not necessary
to use random ports for these types of applications and it doesn't buy
you anything.  Often, in fact, it makes your life more difficult as
firewalls are more difficult to configure.


I'm having difficulty with this one. If SSH is done thru only one port, then:

1. The session is continually being interrupted by others wanting to login via SSH.

2. Only one login is allowed.

I thought that the port(s) and the Ip number made up the connection. SO on port 6987 and on port 32123 should both be able to talk to say port 25 on (all numbers literally typed at random for example use only, I am sure one of them will turn out to be illegal)

I suppose it is possible for SSH to do multiple sessions but why ignore a well-known, and therefore well-bugged, protocol?

BTW, the little guy listening is called a daemon. The reason he's said to be listening is because he is using synchronous input protocol and must wait until there is input.

    --- Shawn

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