port trick

Hi,
Basically I want to be able to connect to different programs from the
same network port. The differentiation may be with, e.g., username,
with url,... etc.

so assume I want to use port 22 with username joe to connect ssh, but
username jack should connect to ftp with the same port.

I guess there must be a programme that will listen on 22, collect the
info from incoming request, and connect incoming request to the
approppriate programme. There must be such a killer already isnt it?

Is already there such a program, any ideas? thx.

On Fri, 24 Mar 2006 07:47:15 -0800, oguz wrote:

> Hi,
> Basically I want to be able to connect to different programs from the
> same network port. The differentiation may be with, e.g., username,
> with url,... etc.
>
> so assume I want to use port 22 with username joe to connect ssh, but
> username jack should connect to ftp with the same port.
>
> I guess there must be a programme that will listen on 22, collect the
> info from incoming request, and connect incoming request to the
> approppriate programme. There must be such a killer already isnt it?
>
> Is already there such a program, any ideas? thx.
>
That is non-standard. AFAIK, servers start listening on the port they
will service. The sever can use the standard port numbers (22 for ssh) or
they can use another (2222 for ssh).

In your case you are talking about the port moving around depending
upon who is at the door. Just one question: suppose joe wants to connect
while jack is connected. Which server will be active at that moment?

There is also a thing called port knocking. Maybe that is closer to
what you want. STFG.

--
Douglas Mayne

On Fri, 24 Mar 2006 07:47:15 -0800, oguz wrote:

> Hi,
> Basically I want to be able to connect to different programs from the same
> network port. The differentiation may be with, e.g., username, with
> url,... etc.
>
> so assume I want to use port 22 with username joe to connect ssh, but
> username jack should connect to ftp with the same port.
>
> I guess there must be a programme that will listen on 22, collect the info
> from incoming request, and connect incoming request to the approppriate
> programme. There must be such a killer already isnt it?
>
> Is already there such a program, any ideas? thx.

The answer is no.
No such things exist because there is no relation between port number
and users.

If you are the client :

Client application use a source port number increasing with the number of
connections used by the client computer. And they do send their requests
toward a destination port being serviced by a deamon or service on a
server.
Obviously, you need to have standard service ports so clients can
connect to your services.

If you are the server :

Server software answer to the source port number of the client.
So if "joe" and "jack" but send packets toward the server with
the same source and same destination port, then how do you think
that the server will separate them ? And how will the client computer
receiving two packets for different users will separate them ?


So what you ask is not a good idea.

Two things.

You might use a port forwarding rule on a firewall to do such a thing.
But :
- trouble-shooting will be harder, and
- Security will not be really increased...

Forget that Idea...