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Terminal commands for other port identification
Authored by: Palijn on Jun 29, '02 06:05:10AM

For those of you who don't want to use a shareware for this, it is fairly easy to find out what port a TCP connection uses with the Terminal.
Just open the Terminal and type "netstat | grep tcp" to get all the open TCP connections.
For a particular connection to a server , just type "netstat | grep" and you should get all open connections to/from .
The FTP control connection is indicated by a text on the 5th column (for the curious, .ftp is really port 21 translated to the "ftp" text by a lookup to the /etc/services table. Unixism...)
The various (if existing) FTP DATA connections - i.e. the one you want to control the bandwidth - are displayed with where XX is really the port used by the data transfer.

Interesting note:
Usually the data port occurs to be 20 if you don't use passive FTP and you have only one FTP transfer running at a time....time-saving default ;-)

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Terminal commands for other port identification
Authored by: Embro on Jun 30, '02 11:13:48PM

Thanks for that info. I really like IPNetMonitor but I knew there had to be a terminal commmand that the info was coming from. Gotta love Unix :-) The author(s) of Carrafix mention on their web site that they are/were going to make the source available. I emailed them today about his because I'd love to make this more automated. It seems that this should be a normal network function since oversaturating the channel just kills the rest of your network flow.

I'll post back here if/when any progress is made.

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More terminal commands for other port identification
Authored by: iv on Jul 02, '02 02:04:28AM

If you want more information than what netstat gives you, try lsof.

E.g. sudo lsof -i shows all open network sockets, their status, commands that opened them and their PID etc. This way you can easily see, what all those open ports do.


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