determine tcp port number

[hoong]

my project requires me to read the data from one TCP port and process the data then transfer it out from another TCPO port. (using PXIe-8115 which have 2 tcp port). problem is i have no idea how to determine the port number of the TCP port.

in what way i can determine the port number of both port?

[rolfk]

Well, you have some spec that specifies to use a certain port for your protocol. If you design the protocol you can choose the port.

So what is your problem? Try to be more cleear what you actually want to do. Right now it sounds like you are looking for something that only you yourself can know.

[hoong]

i want to see what effect of different type of modulation towards the performance of a certain signal being transmitted through space, ie. free space optical communication link.

the thing that i want to do is i want to read date from a tcp port, changing its modulation type and then re-transmit the processed signal through another tcp port.

the problem i facing is i don't know which port number should i read from and which port should i retransmit the signal. 

[rolfk]

it's still as clear as mud. Who produces the data you want to read? Where does it come from? What protocol is used?

[hoong]

the signal is produced by internet lan cable. i intended to transmit internet signal in free space optic environment. 

[hoong]

here is an example i found online but i couldn't understand it. the instruction says the server need to be run before client. but the port number seems a little bit random to me but it did manage to get some signal. 

can i know where the signal come from and how i can determine the correct port number. i know this question mayby sounds basic or even stupid. but i really don't have much knowledge on Labview. any help would be useful. 

[Dennis_Knutson]

I don't think your question is related to understanding LabVIEW. if you want to know what ports are currently being used on your pc, use the netstat command. To start with common ports and ports you can use, you might want to start at http://en.m.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers. Some basic understanding of tcp/ip is necessary for your project, if I understand it correctly.

[hoong]

by using the netstat command, i get the following reading. but the port number is changing everytime. which number should i take as port number?

[Dennis_Knutson]

You certainly don't want one that's currently being used unless one of them is from the application you are testing. Your statement that the signal is being produced by the Ethernet cable is just plain silly. If you intend to generate traffic, then it will be your application that does the generation with an unused port that you select and will not conflict with ports that are reserved for something else. Just like the examples you posted.

[hoong]

i really do not understand. say i want to analyse the data flow of the ethernet cable. which port number should i put? to make sure i am not mistaken, the port number is the number beind my ip address right?