I'm trying to write a program that will show a DHCP client list in Java. I want to get the IP addresses, MAC addresses and the host names of all the devices connected to my wifi network.
I have a Belkin router. Its homepage has a 'DHCP client list' option which when clicked shows me this table :
That's exactly what I'm looking for. But I want to show all this data in the form of a list in a Java Swing program. I also want to be able to update this list by pressing a refresh button. Is there any way to achieve this?
It should look something like this :
I've written a basic java program that shows all the IP addresses that are online. Here's the code :
public static void main(String[] args) throws IOException {
InetAddress localhost = InetAddress.getLocalHost();
// this code assumes IPv4 is used
byte[] ip = localhost.getAddress();
for (int i = 1; i <= 254; i++)
{
ip[3] = (byte)i;
InetAddress address = InetAddress.getByAddress(ip);
if (address.isReachable(1000))
{
// machine is turned on and can be pinged
System.out.println(address + "is online");
}
else if (!address.getHostAddress().equals(address.getHostName()))
{
// machine is known in a DNS lookup
System.out.println(address + "is in a DNS lookup");
}
else
{
// the host address and host name are equal, meaning the host name could not be resolved
System.out.println(address + " is not online");
}
}
}
But this doesn't serve the purpose and it's really slow. I want to write a Swing program that'll show me the DHCP client list as seen in the image above.
Any help is appreciated.
I would think about three possible alternatives:
1-The one you implemented that is slow but it can work. You need to find a JAVA API to get the MAC addresses of received messages (I don't know if it exists or not). You can also send ARP messages asking "who has this IP address) and obtain the MAC address from the response. Use some Java interface for pcap library: jNetPcap vs Jpcap , http://jnetpcap.com/
2-Create an app that accesses your router web interface using HTTP and sending the appropriate messages with data as if you were using the UI. In this way you can programatically follow the steps a human would go and get the list that you browser shows, parse it and obtain the data.
3-If the router/access point provides a web API, which I doubt, you can use it.
Related
I am trying to program an android app dashboard(latest Java android 5.1 lollipop) that would be able to control my govee lamp which has a LAN control api which connects to a multicast address on my LAN(239.255.255.250) but I need a way to find the IP of the specific lamp so that I can send it commands after user interaction on my app.
Pinged the multicast IP and got no response(operation timed out). Looked around google for a way but couldn't find anything so wondering if someone here could help me out. TY for your time :)
Assuming you know the mac address you can send a reverse ARP packet (Reverse Address Resolution Protocol) to obtain the IP address. ARP itself is normally used to map an IP address to the mac address so the local router can properly forward the packet. RARP does the opposite.
Another way is to interrogate the local ARP cache from within the program on any attached device and see if that has it. So on a windows OS within the program you can initiate an arp -a in the console window to see the current arp cache. The only caveat is that the particular value may have time out and been removed.
Here is an example of the latter.
String mac = "1c-7e-81-9e-48-e8";
try {
Runtime rt = Runtime.getRuntime();
// send broadcast address
rt.exec(new String[]{
"ping","-n 1 -w 200 192.255.255.255"
});
// interrogate arp cache
Process p = rt.exec(new String[]{
"cmd.exe","/c","arp","-a"
});
BufferedReader in = new BufferedReader(
new java.io.InputStreamReader(p.getInputStream()));
String line1;
while ((line1 = in.readLine()) != null) {
if (line1.contains(mac)) {
System.out.println(line1);
}
}
} catch (Exception e) {
e.printStackTrace();
}
prints something like
192.168.1.107 1c-7e-81-9e-48-e8 dynamic
The above may need to be adjusted to fulfill your exact requirements.
Of course the easiest way might be to force the issue and assign a static address of your choosing.
I am deplyong a web application in the Internet and I am checking whether the user's login is valid by checking its client IP address (e.g. 192.168.2.XXX). Actually, I have found a working code (below). This code was completely working before, but after some time, its output is not the same anymore. Now, this code only gives me 1 IP address which is the server's IP address. What is wrong with my code? How can I get the client's static IP address rather than the server's IP address? I have also tried other solutions such as getRemoteAddr() and request.getHeader("PROXY-CLIENT-IP") but it is not working.
Java:
String ipAddress = request.getHeader("X-FORWARDED-FOR");
if(ipAddress == null)
ipAddress = InetAddress.getLocalHost().getHostAddress();
Your are mixing two levels of abstractions and that is rarely a good thing.
The header X-FORWARDED_FOR is inserted by a load balancer or proxy. If the client reaches the server directly, then this header isn't present and you are executing this code InetAddress.getLocalHost().getHostAddress();. Which does exactly what you say: It is retrieving the IP address of the host where this piece of code is running, i.e. the web server.
See also here: Getting the client IP address: REMOTE_ADDR, HTTP_X_FORWARDED_FOR, what else could be useful?
Ok, I am quite new to network programming and I am trying to solve this problem:
I have GUI based Java SE game for max 7 players and I want it to support multiplayer over the Internet.
Every instance of game would have its own client sending and receiving string.
And here comes the problem I cannot sufficiently solve. I need server and its only functionality is keeping client's sockets opened and on receiving some string just forward it to other clients. My first idea was to run server on the first player's machine and other players can connect to that server via its IP from outside. Now I discovered that getting public interface IP is not that easy as I thought so I searched and found the code written below to get some IP's that SHOULD be available from outside. When I try this at localhost, resulted IP is always some IPv6 + port and connecting from client using this credentials is successful and it works. When I start the server on another machine and copy these credentials for connecting from another computer it fails (it either doesn't connect or if it does and client sends message, server doesn't receive any).
So my next idea was to use some public IP on remote hosting server. So there would be some server running 24/7 (or if I programmatically from game tell him so) and I use its IP to unite all clients. I just don't know how to make this thing working and what technologies use.
I hope I explained my problem clearly and thanks for any ideas or even solutions :)
Get machine's public interface IP (where server is running) and prints that out code:
Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
while (interfaces.hasMoreElements()) {
NetworkInterface iface = interfaces.nextElement();
if (iface.isLoopback() || !iface.isUp()) { //127.xxx loopback
continue;
}
Enumeration<InetAddress> addresses = iface.getInetAddresses();
while (addresses.hasMoreElements()) {
InetAddress addr = addresses.nextElement();
String tmp = addr.getHostAddress();
if (tmp.startsWith("192.168.") //local IP
|| tmp.startsWith("10.") //local IP
|| tmp.startsWith("172.16.") //local IP
|| tmp.startsWith("172.31.") //local IP
|| tmp.startsWith("169.254") //single network IP
|| tmp.equals("255.255.255.255")) { //broadcast address
continue;
}
//cut "%net9","%wlan" etc stuff off
IP = tmp.substring(0, Math.max(0, tmp.indexOf('%')));
port=server.getPort();
System.out.println(IP + " " + port);
}
}
if running on a "local network" then having a serversocket is fine, but we deal with NAT and the internet which means that 98% of machines are not directly internet visible. (i.e. opening a TCP port for listening on the machine will not result in the machines Internet IP address having that port be listened to. )
The initial option would be to have a server on public hosting which mediates communication between players and each players machine is responsible for maintaining 'game state' but then you run into the issue of synchronization. (e.g. one players machine thinks that they have hit and killed another player prior to that machine receiving a command to tell it that the opponent has moved. )
The current method of thinking for this paticular problem is to have the server maintain the 'game state' (e.g. player positions, health, weapon damage, etc. )
having players send 'commands' to the server (e.g. move, fire, jump. ) and then having the server report to all players the 'minor' game state changes. (so Time becomes an important factor and all messages between clients and server need to be timestamped. )
so your clients maintain what they believe 'game state' to be, recieving updates from the server to 'correct' errors.
In addition to this every once in a while the server should send a dump of the entire 'game state' to each player as a 'sync' message to ensure what they believe to be the game state 'is' the actual game state.
If your language of choice was "C" it would be trivial to take the md5 checksum of the entire game state structure and then transmit this to players periodically and only performing a sync message..
The links below should give you a good starting point.
A good start
And the enclosing page with a little bit more detail
Is there a way to find :
computer name
Operating system
hardware type(laptop or desktop)
Of a give IP or MAC address in java. I've been give a task to
get that data. I'd really appreciate a code sample or if you know of any
libraries that can be used. eg :
If I were to use an IP address of a computer on the same network. I would like to know the name of the computer and which OS they are using and other hardware metadata if that's possible.
If you're trying to find out the hostname associated with an IP address, use InetAddress#getHostName(), though that will only work if the local network has hosts registered for reverse DNS. Finding out another host's OS requires either a service you run that tells you or inference through fingerprinting, which isn't available from Java and isn't entirely reliable.
Getting the mac
The proper way to do this is to use the ARP protocol, but that resides at the Data Link Layer to which Java provides no direct API access. So you'd have to go native for a good solution. Use jNetPcap to gain access to this.
Getting computer name and OS
This would require you to tap into some protocol that provides that data. NBT provides this kind of data.
import java.util.Map;
public class EnvMap {
public static void main (String[] args) {
Map<String, String> env = System.getenv();
for (String envName : env.keySet()) {
System.out.format("%s=%s%n",
envName,
env.get(envName));
}
}
}
I guess you need the following properties:
COMPUTERNAME
OS
regarding MAC Addrss and IP Address you have 2 options:
use
InetAddress ip;
try {
ip = InetAddress.getLocalHost();
System.out.println("Current IP address : " + ip.getHostAddress());
} catch (UnknownHostException e) {
e.e.printStackTrace();
}
or use ipconfig/ifconfig output but I'll leave the choice it to you
Anyone could you please help me to list the name of all computers connected to the LAN with JAVA?
One way you could solve this without using outside system calls would be to try every single possible IP address.
Iterate over addresses, sending data to each one using something like this...
for (int i =0; i<100; i++) {
String ip = "192.168.1." + i
InetAddress address = InetAddress.getByAddress(ip);
}
Any responses you get would indicate an active IP. You will be a limited by your subnet in this approach, however.