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Full Discussion: Help me understand ports and port forwarding please
Special Forums IP Networking Help me understand ports and port forwarding please Post 302838959 by syregnar86 on Wednesday 31st of July 2013 02:11:39 AM
Old 07-31-2013
Help me understand ports and port forwarding please
I have a few questions below on ports.

From my understanding ports are what allow information to come into your computer and each port interprets/allows specific information/data to come in. Is this correct from a ball park perspective? If not could some elaborate on this please.

What commands from terminal can I run to scan for open and closed ports on my mac?

My friend and I tried doing a remote log in to each others mac books using ssh and received a port 22 error. I've heard that you can reroute or forward this port 22. What is my computer actually telling incoming information to do when it forwards a port?

Last question, opening up these ports (port 22 for example), I would think would create a security risk. Therefore, how much at risk are the two computers with an open port 22 and how on earth can ssh be secure if it requires an open port.

I apologize for having so many questions however understanding IP addresses and using the ssh command really requires some basic knowledge on how ports work.
Last edited by syregnar86; 07-31-2013 at 11:46 AM.. Reason: spelling
 

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LEARN ABOUT OSF1

iscc

iscc(7) 						 Miscellaneous Information Manual						   iscc(7)

NAME

       iscc - serial communications interface

SYNOPSIS

       controller  iscc0  at  isa0

DESCRIPTION

       An  onboard  Zilog  8530  DUART	provides  AXPvme-based Single Board Computers with console (CON) and auxiliary (AUX) serial communications
       ports.  Both serial communications ports can operate at baud rates from B50 to B38400,  excluding B134 (see tty(7)).

       On AXPvme Single Board Computers configured with a graphics head as the system console, the CON serial communications port (/dev/tty01)	is
       available for use by application programs as an additional communications port.

       In  the	absence  of a graphics head, the CON serial communications port (/dev/console) becomes the system console. When used as the serial
       system console, the CON serial communications port always operates at 9600 BPS, 8-bits, and no parity.

       Regardless of system console, the AUX serial communications port (/dev/tty00) is always available for use by application programs.

RESTRICTIONS

       Data communications equipment attached to the CON serial communications port must be set to 9600 BPS, 8-bits, no parity when configured	as
       the serial system console. The iscc terminal driver enforces this restriction.

       No modem control is supported for either the CON or AUX serial communications ports.

FILES

       console terminal local terminal local terminal

RELATED INFORMATION

       console(7), devio(7), tty(7), MAKEDEV(8) delim off

																	   iscc(7)
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