Home/ Questions/Q 9182319
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-17T18:31:55+00:00

I am coding a program that necessitates having two machines talk to each other

  • 0

I am coding a program that necessitates having two machines talk to each other via TCP.

I have a (very) basic familiarity with the java.net Socket classes and related things. I am worried about routers/firewalls blocking the connection. All I need to do is get a port open in order to use the Java STL Socket classes.

I was told to look into using upnp by a friend, and another stackoverflow question regarding upnp suggested using Cling. As a network programming novice, Cling seems like overkill for this (and I am not advanced enough to fully understand the manual).

I am sorry if I am asking the wrong question, looking in the wrong place, etc. All I want to do is connect two machines to send some floats back and forth without having to manually go into my router and forward ports.

Is there anything in the STL that does this automatically, or any simple libs?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    First thing first: there’s no such thing as “STL” in Java. You’re probably referring to the basic Java SDK.

    Second, you are asking for “simple means” to perform an operation that is, from a networking point of view, not trivial at all. Look at the most basic task that one of your programs (program A) will have to do: denoting the network location of its “target” (program B). If program B is behind a router, what do you know about program B’s network location? nothing. All you know is the router’s address.

    Same with firewalls. You’re concerned about firewalls blocking your connection? well, if your firewalls are any good, then you want them to block all connections except for pre-approved ones.

    For programs separated by a NAT, the only sensible method to go about doing what you’re looking for is to use UPnP. If Cling is an overkill, try something like weupnp.

    There’s no free lunch, though.

    If there is no network “masking” device (such as a router) between program A and program B, then very simple TCP/IP programming using the Java SDK should just work. If there are networking devices along the ways, you’ll have to cope with them by means of configuring your devices, or using UPnP.

    • 0