TCP Port 828

[williamlweaver]

I'm starting a new LabVIEW project that will use WiFi TCP communication between handhelds.

After reviewing the examples provided in LV 7.1 (PDA TCP Data Server.vi/PDA TCP Data Client.vi) I noticed these examples use TCP port 828, listed as "itm-mcell-s" on the IANA Well Known IP Ports list.

A previous post in the CVI forum suggests applications should avoid the well known ports below 1024.

Anybody know why 828 was chosen for the example code?
Is there a good reason to use/not use it?
Should I pick a port in the Private Range and get on with it?

Many thanks!

-Bill =]

[altenbach]

The only requirements is that both server and client agree on a port for the server.

You should definitely stay away from often used service ports for the simple reason that the server application will not be able to run IF that port is already in use. This will not be very likely with port 828, it is a rarely used port and thus relatively safe to use.

If you use a well-known port for your custom server, you will have two possible problems:
(1) The server will fail to start because of conflicts (see above).
(2) You'll get stray traffic that your server will not understand, especially if you are not behind a firewall and use a port that is often exploited. For example Dshield.org has reports on port scanning activity for each port number. You should definitely stay away from e.g. port 135, but many ports >1024 are also favorite targets. (OTOH, You can also see that 824 is very quiet.)

To see what server ports are in use on your machine, you can do a "netstat -an" (windows), look for lines ending in "listening".