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 SUSE
aplaymidi
APLAYMIDI(1) General Commands Manual APLAYMIDI(1)
NAME
aplaymidi - play Standard MIDI Files
SYNOPSIS
aplaymidi -p client:port[,...] [-d delay] midifile ...
DESCRIPTION
aplaymidi is a command-line utility that plays the specified MIDI file(s) to one or more ALSA sequencer ports.
OPTIONS
-h, --help
Prints a list of options.
-V, --version
Prints the current version.
-l, --list
Prints a list of possible output ports.
-p, --port=client:port,...
Sets the sequencer port(s) to which the events in the MIDI file(s) are sent.
A client can be specified by its number, its name, or a prefix of its name. A port is specified by its number; for port 0 of a
client, the ":0" part of the port specification can be omitted.
For compatibility with pmidi(1), the port specification is taken from the ALSA_OUTPUT_PORTS environment variable if none is given on
the command line.
-d, --delay=seconds
Specifies how long to wait after the end of each MIDI file, to allow the last notes to die away.
SEE ALSO
pmidi(1)
playmidi(1)
AUTHOR
Clemens Ladisch <clemens@ladisch.de>
15 Feb 2004 APLAYMIDI(1)