I'm working on a project, and basically I need this program to find a list of all connected IP addresses to a network, such as going to your network connections in Windows. I've looked all over the internet, and I cant find what I'm looking for and I hope someone can!
This program cannot just crunch numbers (such as pinging all possible IP addresses), it needs to be faster than that. Being able to just connect to the network and obtain a "list" of all IP's that it can see would be perfect. Using the docs.oracle.com webpage did what it was supposed to, but there were too many extra results (including Eth10, etc). Also, the only IP address it listed that wasnt my own didnt match any active computers, so I dont know what was up with that... (192.168.0.9 was listed, the only other active connection was at 192.168.0.10, maybe I'm missing something?).
What is a way to do this? Sorry if I'm unclear, I'm able to be clearer if there's something specific, hope this helps!
Thanks!
EDIT: I hope this helps; I want to do this in java, because for my designed program to work it needs a list of active IP addresses connectable to the active machine. Meaning that if I run it on a laptop at a school, I need all the IP addresses that I could connect to on the network. It is a network thing, but it does need to be done in java. The purpose is for a file manager, otherwise its pretty tough to explain. Does that help?
The only way to do what you are asking is via brute force. It can be done somewhat quickly by creating multiple threads that fire off TCP SYN requests to random IPs on the network (this is what NMap does). If you had access to the DHCP server then you could likely get a list from that point. I would warn you to tread very lightly. Running NMAP or doing port scans on a network is considered an attack by many network admins... you could get yourself in to trouble (they WILL notice).
Related
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.
I want to develop a software, my proper way is JAVA, It sounds simple, but has its own problems.
I have a Network in which there are some devices ( about 400 radios or more)
I do not know their IP.
I just know the first and second part of their MAC addresses.
I want to find out their IP and the whole Mac address of all.
They are in my network, and i have forgotten their IP, and also MAC.
I found this Link useful, but in this solution it is about remote connection to nmap and also you should known the range of IP.
Note that this not about HACKING Or better to say is not about CRACKING or something like this, I have thousands of Radio's and they have been reset and need to be re-config.
Actually i need their MAC to config more than IP.
There are other questions on the net, but they are about having subnet, I do not have subnet of the LAN Network.
Now i am looking for any solution with java or other programming languages, with ARP or dd-wrt something like that, any suggestion? or any solutions? Any sample?
I appreciate this.
Thx all.
If this is your network, inspect ARP tables form network devices. You get all MAC addresses and corresponding IPs. Use SNMP protocol and corresponding libs to get this data form your Java code.
To test this approach use snmpwalk utility.
I was wondering if someone could give me a clue. The situation is we have one computer that has a server application, the rest have a client application. Now my question is how would i keep track of the server ip address? What I want is have the clients automatically hunt the server application, regardless of the ip address and find it, because using a wireless network computers are using DHCP. So I was wondering is there anything that can be buried in a computer using Java with which other computers can identify the application. Thanks.
The "good" way is to use DNS (imho the ONLY solution in a productive environment), as #Peter Lawrey already mentioned, and i would prefer that solution.
You have two other possibilities:
Let the server broadcast his address on the network.
Let the clients scan the network.
Both this solutions are not ideal, because you create a lot of noise on the network, may be blocked by a firewall, etc. Therefore, i really suggest you to use DNS.
If you can not use the DNS solution i would go with a solution that lets the clients search for the server.
Take a look at this SO question, might get you started.
If they're on the same physical network, your server can broadcast its IP address via UDP to the broadcast address for that sub net.
You could even follow the uPnP standard.
Alternatively, you could host the location of the server from a known other location, like a web server. For example, call an action on the known web server to retrieve the IP address of the server. This allows you to utilize DNS to look up the first host, then go from there.
If you know the DNS-Name of the server you can use that name instead of the IP. Java takes care of the DNS lookup.
Otherwise, I guess the simplest solution is just to scan the IP range of your network and just try to connect to each IP and test if it works.
Other solutions would include broadcasts by the server and would be much more complicated and maybe overkill for a application hosted in a small network.
I have been given a project in which I have to share files with peers without any intermediate server. I want to know how to know how many hosts are online on the network and how to connect to them. I have to roughly make Routing table for the hosts in my computer through Java.
You need not to keep any track of routing. All you need is to know the endpoints addresses.
You may find out if a host is connected to the network by establishing a connection with this host.
You mentioned that there will be no intermediate server, so the NAT hole punching is out of scope of your question.
As the starting point look at java.net.Socket class documentation.
I'm going to assume that this is on a private network. Something that's relatively contained. Letting them find each other over the internet sounds like a nightmare.
So, given this, one model for your peers to find each other might be to select a standardised sequence of ports and an alive signal. Then when a peer searches for others, it simply goes through all the IPs on the network and makes a request on that port number. If it gets an alive signal it adds it to a table. The signalled computer would have to record the new comer as well.
You'd have to select the port sequence such that they're generally unused on the network. (Quite large) I say sequence so that there's a preference in ordering to speed up the search.
To speed up the search even more, when an alive signal is sent, it could also send it's peers table and the IPs it checked (and the ones it received in the same way). Then the new peer would only have to check new IPs on the network since old IPs with a new instance of the program would establish themselves.
Hope that helps
i'd suggest you not to go with mac address,it will be better if you turn your dhcp off of your router (if you can include one of course........but if you only can include an hub you'll be forced i guess to use mac address).and use manual addressing for your ipv4 address,and you will be able to easily connect to the other computers.
I have been struggling with this for the entire day now, I hope somebody can help me with this.
My problem is fairly simple: I wish to transfer data (mostly simple commands) from one PC to another over the internet.
I have been able to achieve this using sockets in Java when both computers are connected to my home router. I then connected both computers to the internet using two different mobile phones and attempted to transmit the data again. I used the mobile phones as this provides a direct route to the internet and if I use my router I have to set up port forwarding, at least, that is how I understand it.
I think the problem lies in the method that I set up the client socket. I used:
Socket kkSocket = new Socket(ipAddress, 3333);
where ipAddress is the IP address of the computer running the server. I got the IP address by right-clicking on the connection, status, support. Is that the correct IP address to use or where can I obtain the address of the server? Also, is it possible to get a fixed name for my computer that I can use instead of entering the IP address, as this changes every time I connect to the internet using my mobile phone?
Alternatively, are there better methods to solving my problem such as using http, and if so, where can I find more information about this?
EDIT:
Would it be possible to have the server program running on a server on the internet somewhere. My original server would then be a client that send information to this server. This server would then pass this information to my original client and vice versa. That way, the IP address of my computer won't matter, as I only need to know the address of the server hosted somewhere on the web. Does this seem like a better solution? Where do I begin implementing such a solution?
Thanks!
When you connected to the server that serves StackOverflow, did you type in the IP address? It's 64.34.119.12, if that jogs your memory.
You probably didn't. You probably typed "stackoverflow.com". There's a huge, complex, clever, and in some ways, poorly implemented system called DNS that translates sensible and human-readable names into IP addresses.
One problem with DNS, though, is you need a "static IP", which is exactly what it sounds like: an IP address that doesn't change, which is exactly what you don't have.
So, what can you do?
You can buy a static IP account from your ISP (pretty expensive)
You can use some proxy out in the Internet (a machine that does have a static IP and is willing to bounce your packets back and forth -- I'm not aware of any service that does this for you; you could write one and put it up on Amazon Web Services or Google App Engine, both of which would be free at your level of usage, but they'd be slow, since every packet trying to cross your living room would have have to go via some data-center in Virginia).
You can keep doing what you're doing, looking in the net-configuration of your machine.
You could speed (3) up a little by having your server program look up its own IP address and print it out where you could see it and type it into the server by hand.
You can use DynDNS, as Sergey mentioned (this is the "right" solution, in that it's very general, it just might be a little complicated to set up)
You can use multi-casting.
Multi-casting is an interesting solution, and it may work for you. The idea is, when your server starts up, it announces to the net, "Here I am, I'm providing X server, here's my IP address, talk to me." The problem is, a multi-cast won't leave your living room. Obviously, if every multi-cast were spread to every computer on the Internet, the whole thing would collapse, so your router will ignore, and not route, multi-cast packets. That may or may not be a deal-breaker for you. EDIT Re-reading your question, I see it is a deal-breaker for you. I'd go with #5, but be aware there may be routing issues (address translations that prevent a server from knowing the address that other computers can find it at) or fire-wall issues (that is, your ISP may prevent your server from receiving incoming packets even if the address is correct).
using a direct socket connection with a port like 3333 is usually complicated because different network configurations.
firewalls will make a pleasure preventing the connection, or killing it from time to time.
maintaining a 2-way connection can be a nighmare. the SIP protocol is struggling with this kind of problems.
For a simple application, i suggest you look into the comet technology, where your clients can establish an http connection with a shared server. The server can then bridge commands between them.
html5 will also bring the websocket protocol to the table.
I got the IP address by right-clicking
on the connection, status, support.
Not sure about the "support" part, and I'm not on a Windows machine right now, but I think that the most easy and reliable way to figure out the IP address on Windows is to run "ipconfig" from the command line (Win+R, type "cmd", then "ipconfig" in the opened window). This, of course, should be done on the server side.
However, the problem is that depending on the ISP your IP address may be not within the Internet, but within a local ISP network (so-called NAT). In this case, you'll need to use some sort of black magic called TCP hole punching, which is very complicated and not guaranteed to work. You can figure out if your address is local or not by looking at it. For IPv4 local addresses are almost always like 10.x.x.x or 172.16-31.x.x, or 192.168.x.x. Don't know about IPv6.
You can also check your IP by visiting one of the special sites like www.whatismyip.com. If the address they tell you is different from the one you see by running "ipconfig" or looking at the connection properties, then you're almost certainly behind a NAT (or your ISP is using a transparent proxy, but that's rare).
If you are directly connected to Internet (no local addresses and NAT), then you should also check if you have any firewall software and either to configure it to allow connections to the port you use, or make sure it's in "ask the user" (and not "silently reject") mode, or just disable it completely (this may put your computer at risk, especially if there is no anti-virus software or the system isn't up-to-date).
Also, is it possible to get a fixed
name for my computer that I can use
instead of entering the IP address, as
this changes every time I connect to
the internet using my mobile phone?
Yes, it's possible. There is the thing called DynDNS, and there are DynDNS providers like DynDNS.com, where you can get a third-level domain name for free (like mycoolpc.dyndns.org). You'll have to install and configure some DynDNS client on your PC that will tell the DynDNS server its new IP each time each changed. I don't know anything about particular clients to use because I'm using the one built-in in my home router.
No need to write networking code for this, unless it really floats your boat. Take a look at SCP. http://amath.colorado.edu/computing/software/man/scp.html. There is a windows implementation where you can download putty (windows ssh client), and it is on most linux distributions. Alternatively, you could set up an FTP or SSH server on one or both of the machines.
"a fixed name for my computer that I can use instead of entering the IP address" would be a domain name, these are purchasable online for a few bucks.