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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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)