TCP UDP Ports Question



Trying to get a java program that sends small messages
(believe they are called "datagrams"??) to my computer. The program I am trying to use must be started in a DOS Prompt/Command Prompt and it uses TCP and UDP ports to send and receive messages/datagrams.

The problem: We can not get it to work on our machine
running Win ME or the machine running Win XP, but it will
run on the machine running Win98SE. All machines are
connected to the same Linksys router.

Question: What is it in Win ME or Win XP that could be
blocking these messages from coming in? We are using TCP
port 1500 and UDP port 1500, but this program can use any port number over 1000. Is there something in these
two versions of Windows protecting these ports and keeping these messages from coming in? It appears we are able to connect to the remote Hub/Server, but we cannot receive the messages from the remote hub/server, so we can get out,
but nothing will come in.

Any ideas on what to turn off or on that might open these
ports up or etc to block this possible security issue with the ports?

BTW... we are NOT using WinXP's Firewall (it is off) or any other
firewall and not using XP's ICS

Thank you! The RayBan

PS. I installed the java 2 runtime environment on all
three machine (XP, Me and Win98SE machine) and the XP and
ME machine still would not allow messages in, but the Win98SE will. Just don't get it??? Thanks again!


Not much help,,, but try looking into IRQ groupware... It's great for communicating over a LAN...


Try this... place the computer you are experimenting from, in the DMZ (de-militarized zone).

Connect to your Linksys router > click on Advanced > DMZ Host > and enter your computers IP here. Will it work now?

Willem Moolenaar


Thank you Willem, I have tried the DMZ just to rule it out and that did not fix the problem. The machine running Win98SE is on the same router (have forwarded ports for all machines) and it works fine. Can't figure out what it is about XP that is keeping this from working? Bugging the heck out of me!

Misery, I am not sure I know what IRQ groupware is? Will look it up. Thanks!

The RayBan

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