Is there a way to automatically port forward in java for Socket? Or if you can't do this in java, how else can you do it? Using native functions isn't a problem (I have a feeling that is what I will need), I can add that if it is needed (tho C++ isn't something I really know, I can follow tutorials).
The project I'm working right now has a part in it that has to transfer files but not over localhost, that is why it needs port forwarding.
Yeah you can manually port forward in you router, but that is not something your users should have to do, and most won't even know how to do it.
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I made a networked game in Java using Sockets. It works great, except... only through my LAN. :/ What I want to be able to do is set it up so that I can start the server running on my home computer and send the client code, in an executable jar, to someone else, and have them be able to launch it and connect through the internet. But like... I have no idea how to set up my modem & router for that. :( I have a wireless Clear modem, for which the configuration page looks like this:
http://imageshack.us/photo/my-images/254/modem.jpg
And a Netgear router, whose page looks like this:
http://imageshack.us/photo/my-images/443/routerq.jpg
Right now, in the client and server runner classes, I pass my PC's private IP address along with my chosen port number to the ServerSocket and Socket objects. I hear that Sockets are able to be either UDP or TCP, depending on how you set them up, or something...? I don't do anything like that though, I just instantiate them and pass them the 2 values, and off they go...
In the code for the server:
ServerSocket sock = new ServerSocket();
sock.bind(new InetSocketAddress(IP, 9001));
Code for the client:
Socket sock = new Socket(IP, 9001);
So also, I would need to know how to change the code accordingly with the changes to my router/modem settings.
"IP" is a String representing my computer's private IP, 192.168.1.10, and the program only works if that is the string I pass to the Socket & ServerSocket. Like I said, I have a modem which is connected to a router which is connected to my computer. So, can someone please explain to me (in detail, because I'm a noob) what exactly I would have to do to configure both of them, AND the changes I would have to make to my code?
You'll have to manually port forward, or look at a solution like UPnP or NAT-PMP for automatic port forwarding. Unfortunately, NAT is a pain in the ass to configure and most routers don't properly support it. It's also not a simple task, as you have to support a whole range of different implementations and mechanisms.
It shouldn't be too difficult to set up your router to forward one port to your machine, though. See http://portforward.com/ for an awesome list of how to do it on pretty much any router.
It sounds like you're asking a number of questions here... I'm no network/socket programming specialist, but here's some ideas.
For distribution, you may wish to look into Java Web Start. It'll make it easy for your clients to obtain the app as well as automating updates.
If you're using the Socket constructor like that, the actual implementation will be a system default. You could override this by calling this method with a suitable SocketImplFactory implementation.
As for the IP address and port... Using a hard-coded value for the port should be okay. You'll need to decide on a port or at least some default anyway for clients to connect to. Even so, it might be useful to have the value read from some external configuration file. This'll make it easier should you ever decide to distribute the server app to let other people run servers. They might want to use a different port.
Having the server's IP address (yours) hard-coded in code is definitely a no-no, though. Clients should connect using either an IP address or host name that they need to provide or set in some configuration file. A host name would be required if you don't have a static IP address.
Unless this is something for you and some friends to enjoy, where you can always just initiate a game by providing IP and port in a chat session or something, you'd be better off finding some external hosting solution at a company that takes care of the DNS resolution and network setup for you. These days you'll find stuff like that pretty cheap if you don't have requirements like a Java EE server or database.
EDIT: thought of something else. TCP might be okay for your use-case, but if this is a game that requires minimal lag and quick input synchronization (like a shooter or fighting game) then it's not the best choice. In that case UDP would be better. It would induce the requirement of adding some sort of detection for desync or a mechanism that makes up for any dropped packets.
The problem: In java you can create a socket on the server with ServerSocket(0) and it will choose a random port to listen on. However when you create a socket on the client to send a message with Socket(addr, port) there is no apparent way to determine which port on the server you need to send to. I couldn't find anything about this option through web searches besides the basic "if you put 0 it will chose a random port". Does anyone know or have a resource that could explain what this scenario is supposed to look like from the client end?
Some background: I am currently converting a system from UDP to TCP. The reason I need the server to listen on a random port is that my server/client do not have a strict server/client relationship. So the "server" in this situation is really an application that I need to open multiple instances of on one PC. The old way of having predetermined send/receive ports is causing only one instance to be able to open a port and all communication is being redirected to that instance. My understanding that the best way to fix this problem is for each instance to use a different port, and the best way for that is to do ServerSocket(0). Despite including this background, I do not want comments on how messed up the situation is, only answers pertaining to the problem.
If a fixed port number is not part of the server's documented setup / protocol, then the only way for clients to figure out is to have the running/active servers publish that information in some datastore, the location and details of which are documented and known by the clients, and where that datastore is reachable for the clients.
[Or have the clients run a portscan each time they want to connect. It will work but probably not as fast as your users would like.]
And your situation is indeed messed up.
Perhaps if you are on the same IP subnet with all the servers/clients, then you could use UPnP to signal which random port new instances of your application are running on, and similarly other instances could monitor UPnP to discover this new instance.
I've never implemented UPnP in Java, but suspect libraries are out there..
eg. https://github.com/jupnp/jupnp
I made application with java using socket. My computer is the server and my phone(android ) is the client. Only what i trying to do is to forward String from phone to client PC.
Everything works fine when i configure my router and open the port i using. i don't want every time when costumer will install my application will need to open port in the router.
I thought about using remote server that will run my server code. but i didn't find server that can do that . i don't want to make my pc a server for all costumers.
How does all the chats companies do it without open port?
You must look into UPnP. This is what /most/ if not /all/ torrent clients use to allow foreign connections, without forwarding ports. How chat clients do it is a different scenario. They use hacks such as firewall hole-punching using UDP (with an external server) http://www.h-online.com/security/features/How-Skype-Co-get-round-firewalls-747197.html see this link for details on UDP hole punching.
Also see this article http://www.codeproject.com/Articles/13285/Using-UPnP-for-Programmatic-Port-Forwardings-and-N for usage of UPnP. But this is in C++, but I think you will understand.
EDIT: http://4thline.org/projects/cling/ I found this. I think it can help you.
You had to open port probably because of your routers firewall :). If you already opened let us say port 9090 then every client app (android phone) will be able to connect to it :). Of course if somebody wants to install server on their own pc they would problably forward some ports and disable some firewalls. If you want server with no special requriements lookup VPS'es. :)
Thanks for any answers in advance.
Anyways, I made an android application, (This isn't an android question), and it connects to your computer so you can monitor it. Well I have the server for the computer ready to the client from the phone can access it, it works perfectly. The problem is, You have to port forward, and not everybody knows how to do that. Is there a way so you can programmatically make it so you do not have to port forward?
Thanks again!
You mean you had to set up port forwarding on your router (because you're using a router with your broadband connection)?
No.
You would need to set up a intermediary server on the internet somewhere that both could connect to, then forward the data through that.
You can have both connect to a server of yours. More of a pain than any other method, but guaranteed to work.
I'm not sure about the specifics of the droid, but you may be able to access the droid directly through its IP.
Otherwise you could set up a simple tutorial program, with specific instructions on how to port forward. You could even make a little program to access certain popular vendors port forwarding directly. Maybe just a little thing that asks for a password and connects and does everything automatically. Wouldn't be horribly difficult with some vendors.
I'm messing around with a program to track my internet browsing habits and I'm trying to think of the best way to do it. I have some ideas but I'm not sure how feasible they are.
Somehow hook into firefox. I don't think there's an API that I can hook java into firefox with. I heard something about a firefox java rmi add on that I can access from java but I can't find anything. This would restrict me to firefox, which is fine because I only use firefox.
Emulate Windows "netstat" somehow. I don't want to call netstat because that limits me to Windows. This would be a last case scenario
Socket programming. I can set up a ServerSocket to listen on port 80 but not if there is already something using that port, so it doesn't do what I want it to do, listen to what's already going on on port 80.
Use a packet capture library. This seems like overkill.
Any other ideas?
Sure
Check rabbit a java proxy with monitoring,sniffing and filtering capabilities
http://www.khelekore.org/rabbit/
Use a java local proxy to monitor any request from any browser