address.isReachable won't discover all nodes on a network - java

I have trimmed my code down to the bare essentials, its pretty simple and straight forward.
I have the following code:
public ArrayList<Node> getNodes() throws IOException
{
ArrayList<Node> nodes = new ArrayList<Node>();
StringBuffer root = new StringBuffer(InetAddress.getLocalHost().getHostAddress());
while(!root.toString().endsWith("."))
root.deleteCharAt(root.length() - 1);
//^^ this code gets the ip, for ex 127.0.0.1, and trims the last number, to make it
//^^ 127.0.0. <-- see the trailing 0
for(int host = 0;host < 256; host++)
{
InetAddress address = InetAddress.getByName(root.toString() + host);
try
{
if(address.isReachable(500)) // pings the address
nodes.add(new Node(address.getHostAddress(), false));
}catch(Exception e){new Node(address.getHostAddress(), true);}
}
return nodes;
}
Here is the node class, which is pretty simple:
public class Node
{
public Node(String address, boolean restricted)
{
this.address = address;
this.restricted = restricted;
}
public String address;
public boolean restricted;
}
Here is my main code, which executes getNodes():
case 1:
System.out.println("Searching for nodes...");
NodeDetector node = new NodeDetector(); // this is the class
//where getNodes resides
ArrayList<Node> nodes = node.getNodes();
Iterator<Node> it = nodes.iterator();
while(it.hasNext())
{
System.out.println("Node: "+it.next().address);
}
System.out.println("stopped searching for nodes...");
break;
Here is my output:
Searching for nodes...
Node: 00.00.17.99
Node: 00.00.17.100
Node: 00.00.17.149
Node: 00.00.17.150 <-- this is my computer
Node: 00.00.17.154
Node: 00.00.17.156
Node: 00.00.17.254
stopped searching for nodes...
Now here's the problem
I have a network node discovery tool i downloaded on my phone and it can find at least 5 more nodes. I tried changing the timeout value but still no luck. When i ping an address that is found with the network tool on my phone and not on my computer, the ping is instantly received and returned. This question is similar and it has helped me a bit, but I'm still stuck:
How to do a true Java ping from Windows?
I am running my tool on a mac, it seems to work well picking up other macs, iPods and routers but thats about it. Why can't my program detect the other devices on the network?
Here is the output i get from my network tool on my phone:
00.00.17.99 <-- SMC Networks *
00.00.17.100 <-- XEROX *
00.00.17.133 <-- My Phone (Android)
00.00.17.134 <-- Intel
00.00.17.142 <-- Apple
00.00.17.149 <-- Apple *
00.00.17.150 <-- Apple * <-- this is my computer
00.00.17.154 <-- Apple *
00.00.17.155 <-- Intel
00.00.17.156 <-- Apple *
00.00.17.158 <-- Motorola Mobility
00.00.17.254 <-- Netopia *
I put an * where the tool on my phone agrees with the tool i am writing on my computer. I have ran this test a couple of times, i get the same output every time on both my computer and on my phone, no devices were added or removed from the network during the tests.

After a couple days of research I have come across this as an ok solution:
try
{
Process p1 = java.lang.Runtime.getRuntime().exec("ping -c 1 -W 250 " + address.getHostAddress());
int returnVal = p1.waitFor();
boolean reachable = (returnVal==0);
if(reachable)
nodes.add(new Node(address.getHostAddress(), false));
}catch(Exception e)
{
new Node(address.getHostAddress(), true);
}
The only drawback on this is that it is system dependent. Im going to be the only one using this tool so that really is no problem for me.

Related

Get drive letters of USB 3.0 devices (Java under Windows)

My Java program needs to get a list of the drive letters of connected USB devices, but only those that support USB 3.0 (both the device and the USB port it is plugged into, so that it works with high speed).
Currently I try to use WMI through a PowerShell command my Java programm executes.
I already found this: Powershell: Grab USB Drive letter. But it would also list USB 2.0 devices.
Regarding version detection I found this: How to check the version of the available USB ports? - The PowerShell command I tried is Get-WmiObject Win32_USBHub. This brings up several problems. First: It lists far more stuff than only USB drives (I think also all the USB hubs of my PC). Second: Even though there is a field USBVersion for all items in the list it is always empty.
Update
The essence of my research over the last days is, that there are 2 realms of information I need to connect.
Drives / Logical Drives
Drive Letter
BusType (is equal to "USB" for my matter)
USB devices
Vendor ID and Product ID (VID&PID)
bcdUSB (value within the usb device descriptor, indicating USB Version)
For a given drive letter I need to find the bcdUSB value. But I haven't found a way to get the drive corresponding to a USB device.
What I tried so far
WMI over PowerShell
Relevant commands I found are
Get-Disk // Get BusType
gwmi Win32_LogicalDisk // Get drive letter
// Those make the connection between disk and logical disk
gwmi Win32_LogicalDiskToPartition
gwmi Win32_LogicalDiskToPartition
Even though I get the BusType I couldn't make a connection to bcdUSB
usb4java (Link)
I only get information from the USB device realm here. I can load devices and see ther VID&PID and the bcdUSB value, but no way to map this to drives and drive letters.
lsusb via Cygwin
According to this post the linux command is easier to handle than WMI. So I tried to use it under Windows. But I like usb4java I only got VID&PID + bcdUSB, not the mount point (drive letter).
Searching the Windows Registry
I did a few string searchs in the Windows registry. No success.
Reading Windows Event log
I thought about ovserving Windows events to detect what Drive and what USB device connect at the same time. I didn't even find events when plugging in a USB stick.
Maybe this is what you are looking for:
Find Windows Drive Letter of a removable disk from USB VID/PID
At least someone marked the answer as working... :-)
Since the suggested Link solves this problem for C# not Java and leaves out one step, I'll post my final code here.
Summary
In Java
Use USB4Java to find all connected USB devices with bcdUSB=0x0300
Get Vendor ID and Product ID (VID&PID) for that devices
Via Powershell (with jPowerShell)
Get PnPEntity for given VID&PID
Get related USB Controller
Find associator of that USB Controller that is associated with a disk drive
Get that Disk drive
Get related disk partition
Get related logical disk -> LogicalDisk.DeviceID = Drive Letter
Code
Java class:
class UsbDetector {
private PowerShell shell;
#PostConstruct
private void init() {
shell = com.profesorfalken.jpowershell.PowerShell.openSession();
}
#OnDestroy
private void onShutdownHook() {
shell.close();
}
/**
* Get drive letters of USB 3.0 devices.
*/
public List<String> getDriveLettersForUsb3Devices() throws IOException, UsbException {
List<UsbDevice> devicesUSB3 = getAllUsb3Devices();
ImmutableList.Builder<String> driveLetterList = ImmutableList.builder();
for (UsbDevice device : devicesUSB3) {
String vidAndPid = getVidAndPid(device);
String powerShellScript = buildScript(vidAndPid);
String driveLetter = executeOnPowerShell(powerShellScript);
driveLetterList.add(driveLetter);
}
return driveLetterList.build();
}
private String executeOnPowerShell(String powerShellScript) {
InputStream psScriptStream = new ByteArrayInputStream(powerShellScript.getBytes());
BufferedReader psScriptReader = new BufferedReader(new InputStreamReader(psScriptStream));
PowerShellResponse response = shell.executeScript(psScriptReader);
return response.getCommandOutput();
}
private String buildScript(String vidAndPid) throws IOException {
InputStream psScriptStream =
getClass().getClassLoader().getResourceAsStream("GetUsbDrives.ps1");
String psScript = IOUtil.toString(psScriptStream);
psScript = String.format("$input=\"%s\"", vidAndPid) + "\n" + psScript;
return psScript;
}
/**
* The Vendor ID and Product ID are necessary to find the device via WMI.
*/
private String getVidAndPid(UsbDevice device) {
short vendorId = device.getUsbDeviceDescriptor().idVendor();
short productId = device.getUsbDeviceDescriptor().idProduct();
String vendorIdHexString = String.format("%04x", vendorId).toUpperCase();
String productIdHexString = String.format("%04x", productId).toUpperCase();
String vidAndPid = String.format("VID_%s&PID_%s", vendorIdHexString, productIdHexString);
return vidAndPid;
}
/**
* From all Usb devices find those with USB 3.0. The value bcdUsb is a hexadecimal coded number
* telling us the USB version.
*/
private List<UsbDevice> getAllUsb3Devices() throws UsbException {
List<UsbDevice> devicesUSB3 = Lists.newArrayList();
UsbServices services = new org.usb4java.javax.Services();
UsbHub hub = services.getRootUsbHub();
List<UsbDevice> devices = getAllUsbDevices(hub);
for (UsbDevice device : devices) {
UsbDeviceDescriptor descriptor = device.getUsbDeviceDescriptor();
short bcdUsb = descriptor.bcdUSB();
String bcdDecoded = DescriptorUtils.decodeBCD(bcdUsb);
if (Objects.equal(bcdDecoded, "3.00")) {
devicesUSB3.add(device);
}
}
return devicesUSB3;
}
/**
* UsbHubs can either mount UsbDevices or further UsbHubs. This method searches through the tree
* of UsbHubs for UsbDevices and returns them as list.
*/
private List<UsbDevice> getAllUsbDevices(UsbHub hub) {
List<UsbDevice> devices = Lists.newArrayList();
List<UsbDevice> attachedDevices = hub.getAttachedUsbDevices();
for (UsbDevice device : attachedDevices) {
if (device instanceof UsbHub) {
List<UsbDevice> subdevices = getAllUsbDevices((UsbHub) device);
devices.addAll(subdevices);
} else {
devices.add(device);
}
}
return devices;
}
}
PowerShell script:
# $input = "VID_XXXX&PID_XXXX (this line is added in Java Code)
# For given VID and PID of a USB device we search for
# the corresponding logical disk to get the drive letter.
# The chain of objects is:
# PnPEntity (PnP = Plug and Play)
# -> USBController
# -> Some associator of USBController that has a related disk drive
# -> diskDrive
# -> diskPartition
# -> logicalDisk
# Find PnPEntity for given VID and PID
$usbPnPEntity = (gwmi Win32_PnPEntity | where DeviceID -match $input)
# Get USB Controller related to PnP Entity
$usbController = $usbPnPEntity.getRelated("Win32_USBController")
$usbControllerID = $usbController.DeviceID
# Find objects associated with the USB Controller
$query = "ASSOCIATORS OF {Win32_USBController.DeviceID='$usbControllerID'}"
$associators = ([wmisearcher]$query).get()
# Search through associators
foreach ($associator in $associators) {
# Find associator that is related to a disk Drive
$assoDeviceID = $associator.DeviceID
$diskDrive = (gwmi win32_diskdrive | where PNPDeviceID -eq $assoDeviceID)
if($diskDrive){
# Get logical Disk related to the disk drive
$logicalDisk = $diskDrive.getRelated("Win32_DiskPartition").getRelated("Win32_LogicalDisk")
# Print device ID which is the drive letter (e.g. "C:")
$logicalDisk.DeviceID
break
}
}
Maven dependencies:
<dependency>
<groupId>org.usb4java</groupId>
<artifactId>usb4java-javax</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>com.profesorfalken</groupId>
<artifactId>jPowerShell</artifactId>
<version>3.1.1</version>
</dependency>

get DFS/UNC info progromatically - Java

Ok I'll try and keep this short.
First let me explain exactly what I am trying to get. If you open Windows Explorer and go to a network drive there is a DFS tab there(must have DFS enabled VIA the servers on the network so it may not be there).
In that tab there is a list called the "Referral List"... I want what is in that box. I believe this is the DFS or UNC, you can correct me it will help me.
What I have is the \domainname.com\something$\BUS\blah\myDriveHome but this is tied to something else in that box that contains the actual server that that share is setting on and that share is what I need to run a compliance check.
I cannot use an exe that is not package with Windows 7 not any other exe as we cannot distribute exes.
So what have I done... a VERY thorough search for things like DFS/UNC paths from the command line, powershell, and registry and no go. Command line "net use" only return the linked path and not the server so that is useless.
I only ever post a question when I hit a wall that is taking up to much programming time.
If anyone has an info it would be grateful.
Thanks
I was able to steal the C# code in this answer here and make some modifications so it works with .Net 2.0, and use it within PowerShell:
$dfsCode = #'
using System;
using System.Runtime.InteropServices;
public static class Dfs
{
private enum NetDfsInfoLevel
{
DfsInfo1 = 1,
DfsInfo2 = 2,
DfsInfo3 = 3,
DfsInfo4 = 4,
DfsInfo5 = 5,
DfsInfo6 = 6,
DfsInfo7 = 7,
DfsInfo8 = 8,
DfsInfo9 = 9,
DfsInfo50 = 50,
DfsInfo100 = 100,
DfsInfo150 = 150,
}
[DllImport("netapi32.dll", SetLastError = true)]
private static extern int NetApiBufferFree(IntPtr buffer);
[DllImport("Netapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
private static extern int NetDfsGetInfo(
[MarshalAs(UnmanagedType.LPWStr)] string DfsEntryPath, // DFS entry path for the volume
[MarshalAs(UnmanagedType.LPWStr)] string ServerName, // This parameter is currently ignored and should be NULL
[MarshalAs(UnmanagedType.LPWStr)] string ShareName, // This parameter is currently ignored and should be NULL.
NetDfsInfoLevel Level, // Level of information requested
out IntPtr Buffer // API allocates and returns buffer with requested info
);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_INFO_3
{
[MarshalAs(UnmanagedType.LPWStr)]
public string EntryPath;
[MarshalAs(UnmanagedType.LPWStr)]
public string Comment;
public int State;
public int NumberOfStorages;
public IntPtr Storage;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct DFS_STORAGE_INFO
{
public int State;
[MarshalAs(UnmanagedType.LPWStr)]
public string ServerName;
[MarshalAs(UnmanagedType.LPWStr)]
public string ShareName;
}
private static T GetStruct<T>(IntPtr buffer, int offset)where T:struct
{
T r = new T();
r = (T) Marshal.PtrToStructure((IntPtr)((long)buffer + offset * Marshal.SizeOf(r)), typeof(T));
return r;
}
public static string GetDfsInfo(string server)
{
string rval = null;
IntPtr b;
int r = NetDfsGetInfo(server, null, null, NetDfsInfoLevel.DfsInfo3, out b);
if(r != 0)
{
NetApiBufferFree(b);
// return passed string if not DFS
return rval;
}
DFS_INFO_3 sRes = GetStruct<DFS_INFO_3>(b,0);
if(sRes.NumberOfStorages > 0)
{
DFS_STORAGE_INFO sResInfo = GetStruct<DFS_STORAGE_INFO>(sRes.Storage,0);
rval = string.Concat(#"\\", sResInfo.ServerName, #"\", sResInfo.ShareName, #"\");
}
NetApiBufferFree(b);
return rval;
}
}
'#
Add-Type -TypeDefinition $dfsCode
[Dfs]::GetDfsInfo('\\ad.domain.com\Share')
This code will work with PowerShell 2.0 which is included with Windows 7.
I went another direction with the use of PSEXEC and DFSUtil to find the DFS info VIA the remote PC. Returns a lot of info but I filtered it in PowerShell after reading the file and matching the UNC. I would post the how to but I had to do some major adapting on my end with the info that is on a few other sites for DFSUtil and what to look for and PSExec. I will note this for PSEXEC:
cmd.exe /s /c C:\Temp\psexec.exe 2> $null
That "2> $null" will save you some headaches and your script crashing if the return is in the error channel. You will need to run it in the PS console though without that to catch the error, but when you have a script like mine performing 50+ system checks you don't want the whole thing to halt for just one error.

Get the name and IP of devices on a Wifi network

I know this question has been asked here but it didn't get answered.
I'm writing a simple Java Swing application in which I want to show the name and IP address of each and every device that is connected to my wireless network.
I want to show this list in a JFrame. I searched a lot on the web but couldn't find a way to achieve this. Please help me out Java masters!
Thanks in advance!
I found this code after looking a little bit. It works, but it is slow, and probably not the best way to do it, but it works.
import java.io.IOException;
import java.net.InetAddress;
public class NetworkPing {
/**
* JavaProgrammingForums.com
*/
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))
{
System.out.println(address + " machine is turned on and can be pinged");
}
else if (!address.getHostAddress().equals(address.getHostName()))
{
System.out.println(address + " machine is known in a DNS lookup");
}
else
{
System.out.println(address + " the host address and host name are equal, meaning the host name could not be resolved");
}
}
}
}
Couple things to note, address.getHostAddress() returns the 192.168.0.xxx
and address.getHostName() returns the name of the device like "Kevins-PC"
It's a pretty simple piece of code, but I'll walk through it real fast.
It starts off by getting your localhost IP address (which on a normal household network would be 192.168.0.xxx) and it stores that in a byte[] so it looks something like {192, 168, 0, xxx}.
Then it creates a for loop starting at 1 and going to 254 (because this code assumes a /24 subnet mask (255.255.255.0) but if its running a different subnet mask then it might not be 1-254).
Then in the for loop it sets the third index of the ip to i.
It then creates an InetAddress from that address.
Then it tries to reach it in 1000 milliseconds (1 second), and if it succeeds then it prints the address and says its reachable.
Else if the machine host address (the 192.168.0.xxx) does not equal the host name (like the name of your computer like Kevins-PC), then it says that the machine is known in a DNS lookup meaning it is found in a DNS lookup but it wasnt reachable (so its probably off or not connected, but it has been before), DNS is Domain Name Service. The DNS basically stores the information (your router probably does this).
Finally, else it just says it couldn't be resolved which means it wasnt reachable nor was it found looking in the DNS.
I found this code here and here
UPDATE
So if you run this and you just keep getting something like "192.168.0.5/192.168.0.5 the host address and host name are equal, meaning the host name could not be resolved"
That means that your router (your local DNS) just isn't storing the information OR those devices just choose not to submit their host name to the router, and that is why you will continually get that message. As far as I am aware, there isn't a way around this because those device names literally aren't stored
Try this :)
import java.io.IOException;
import java.net.*;
import java.util.Vector;
public class search {
public static void main(String args[]) throws UnknownHostException{
Vector<String> Available_Devices=new Vector<>();
String myip=InetAddress.getLocalHost().getHostAddress();
String mynetworkips=new String();
for(int i=myip.length();i>0;--i) {
if(myip.charAt(i-1)=='.'){ mynetworkips=myip.substring(0,i); break; }
}
System.out.println("My Device IP: " + myip+"\n");
System.out.println("Search log:");
for(int i=1;i<=254;++i){
try {
InetAddress addr=InetAddress.getByName(mynetworkips + new Integer(i).toString());
if (addr.isReachable(1000)){
System.out.println("Available: " + addr.getHostAddress());
Available_Devices.add(addr.getHostAddress());
}
else System.out.println("Not available: "+ addr.getHostAddress());
}catch (IOException ioex){}
}
System.out.println("\nAll Connected devices(" + Available_Devices.size() +"):");
for(int i=0;i<Available_Devices.size();++i) System.out.println(Available_Devices.get(i));
}
}

How to ping and keep statistics in Java

I have a task to make a simple console pinger in Java.
I tried the following code and I have 2 main issues.
First of all even if I am connected to the internet (I can ping from console any site), when I run the code returns false.
Second, is it possible to track the time of response of the ping?
Here is the code:
try {
InetAddress address = InetAddress.getByName(the_link);
System.out.println(the_link);
// Try to reach the specified address within the timeout
// periode. If during this periode the address cannot be
// reach then the method returns false.
boolean reachable = address.isReachable(5000);
System.out.println("Is host reachable? " + reachable);
} catch (Exception e) {
e.printStackTrace();
}
This is not a good one to use for most external ips.
Instead following can be used
boolean reachable = (java.lang.Runtime.getRuntime().exec("ping -c 1 www.google.lk").waitFor()==0);

Why does this code in repast j for java creates double the amount of "outedge"

I am modeling a supply chain with an customer, retailer and supplier. They are connected in a node. I have found this code. But I do not understand, why this code creates the double amount of outedges. Perhaps, someone can help?
while (it.hasNext()) {
// Find the next agent to link to.
tempAgent = (supply_chain_agent) it.next();
System.out.println(tempAgent);
// Create an edge from the last agent to the temp agent.
tempEdge = new supply_chain_edge("Orders", 1, this.initialOrderPerTimeStep);
// Connect the new edge.
tempAgent.addInEdge(tempEdge);
System.out.println(tempEdge.getLabel());
lastAgent.addOutEdge(tempEdge);
System.out.println(tempEdge.getLabel());
tempEdge.setTo(tempAgent);
tempEdge.setFrom(lastAgent);
// Create an edge from the temp agent to the last agent.
if (lastAgent.getNodeLabel().startsWith("Customer")) {
tempEdge = new supply_chain_edge("Shipments", this.ordering_delay, this.initialOrderPerTimeStep);
} else {
tempEdge = new supply_chain_edge("Shipments", this.delivery_delay, this.initialOrderPerTimeStep);
}
// Connect the new edge.
lastAgent.addInEdge(tempEdge);
System.out.println(tempEdge.getLabel());
tempAgent.addOutEdge(tempEdge);
System.out.println(tempEdge.getLabel());
tempEdge.setTo(lastAgent);
tempEdge.setFrom(tempAgent);
// Move on.
lastAgent = tempAgent;
System.out.println(lastAgent);
}

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