How to ping an IP address

Question

I am using this part of  code to ping an ip address in java but only pinging localhost is successful and for the other hosts the program says the host is unreachable  I disabled my firewall but still having this problem  public static void main String   args  throws UnknownHostException  IOException       String ipAddress    127 0 0 1       InetAddress inet   InetAddress getByName ipAddress        System out println  Sending Ping Request to     ipAddress       System out println inet isReachable 5000     Host is reachable     Host is NOT reachable         ipAddress    173 194 32 38       inet   InetAddress getByName ipAddress        System out println  Sending Ping Request to     ipAddress       System out println inet isReachable 5000     Host is reachable     Host is NOT reachable        The output is      Sending Ping Request to 127 0 0 1   Host is reachable   Sending Ping Request to 173 194 32 38   Host is NOT reachable

User · Answer

You can use this method to ping hosts on Windows and other platforms     private static boolean ping String host  throws IOException  InterruptedException       boolean isWindows   System getProperty  os name   toLowerCase   contains  win         ProcessBuilder processBuilder   new ProcessBuilder  ping   isWindows   -n     -c    1   host       Process proc   processBuilder start         int returnVal   proc waitFor        return returnVal    0

User · Answer

I tried a couple of options    Java InetAddress   InetAddress getByName ipAddress   the network on windows started misbehaving after trying a couple of times   Java HttpURLConnection          URL siteURL   new URL url           connection    HttpURLConnection  siteURL openConnection            connection setRequestMethod  GET            connection setConnectTimeout pingTime           connection connect             code   connection getResponseCode            if  code    200                code   200                This was reliable but a bit slow   Windows Batch File   I finally settled to creating a batch file on my windows machine with the following contents  ping exe -n  echoCount   pingIp  Then I called the  bat file in my java code using     public int pingBat Network network    ProcessBuilder pb   new ProcessBuilder pingBatLocation   Map lt String  String gt  env   pb environment     env put           echoCount   noOfPings        env put           pingIp   pingIp   File outputFile   new File outputFileLocation   File errorFile   new File errorFileLocation    pb redirectOutput outputFile    pb redirectError errorFile    Process process   try       process   pb start        process waitFor        String finalOutput   printFile outputFile       if  finalOutput    null  amp  amp  finalOutput toLowerCase   contains  reply from              return 200        else           return 202          catch  IOException e        log debug e getMessage         return 203    catch  InterruptedException e        log debug e getMessage         return 204         This proved to be the fastest and most reliable way

User · Answer

short recommendation   don t use isReachable    call the system ping  as proposed in some of the answers above   long explanation     ping uses the ICMP network protcol  To use ICMP  a  raw socket  is needed standard users are not allowed by the operating system to use raw sockets the following applies to a fedora 30 linux  windows systems should be similar   if java runs as root  isReachable   actually sends ICMP ping requests if java does not run as root  isReachable   tries to connect to TCP port 7  known as the echo port  This service is commonly not used any more  trying to use it might yield improper results any kind of answer to the connection request  also a reject  TCP flag RST  yields a  true  from isReachable   some firewalls send RST for any port that is not explicitly open  If this happens  you will get isReachable      true for a host that does not even exist further tries to assign the necessary capabilities to a java process  setcap cap net raw eip java executable  assign the right to use raw sockets  test  getcap java executable -   cap net raw eip   capability is assigned  the running java still sends a TCP request to port 7 check of the running java process with getpcaps pid shows that the running java does not have the raw socket capablity  Obviously my setcap has been overridden by some security mechanism as security requirements are increasing  this is likely to become even more restricted  unless s b  implements an exception especially for ping  but nothing found on the net so far

User · Answer

It will work for sure   import java io    import java util     public class JavaPingExampleProgram      public static void main String args       throws IOException            create the ping command as a list of strings     JavaPingExampleProgram ping   new JavaPingExampleProgram        List lt String gt  commands   new ArrayList lt String gt         commands add  ping        commands add  -c        commands add  5        commands add  74 125 236 73        ping doCommand commands          public void doCommand List lt String gt  command     throws IOException         String s   null       ProcessBuilder pb   new ProcessBuilder command       Process process   pb start         BufferedReader stdInput   new BufferedReader new InputStreamReader process getInputStream          BufferedReader stdError   new BufferedReader new InputStreamReader process getErrorStream              read the output from the command     System out println  Here is the standard output of the command  n        while   s   stdInput readLine       null              System out println s                 read any errors from the attempted command     System out println  Here is the standard error of the command  if any   n        while   s   stdError readLine       null              System out println s

User · Answer

I think this code will help you   public class PingExample       public static void main String   args           try              InetAddress address   InetAddress getByName  192 168 1 103                boolean reachable   address isReachable 10000                System out println  Is host reachable      reachable             catch  Exception e               e printStackTrace

User · Answer

InetAddress isReachable   according to javadoc          A typical implementation will use ICMP ECHO REQUESTs if the   privilege can be obtained  otherwise it will try to establish a TCP   connection on port 7  Echo  of the destination host       Option  1  ICMP  usually requires administrative  root  rights

User · Answer

Check your connectivity  On my Computer this prints REACHABLE for both IP s      Sending Ping Request to 127 0 0 1   Host is reachable   Sending Ping Request to 173 194 32 38   Host is reachable   EDIT   You could try modifying the code to use getByAddress   to obtain the address   public static void main String   args  throws UnknownHostException  IOException       InetAddress inet       inet   InetAddress getByAddress new byte     127  0  0  1         System out println  Sending Ping Request to     inet       System out println inet isReachable 5000     Host is reachable     Host is NOT reachable         inet   InetAddress getByAddress new byte      byte  173   byte  194  32  38         System out println  Sending Ping Request to     inet       System out println inet isReachable 5000     Host is reachable     Host is NOT reachable        The getByName   methods may attempt some kind of reverse DNS lookup which may not be possible on your machine  getByAddress   might bypass that

User · Answer

Even though this does not rely on ICMP on Windows  this implementation works pretty well with the new Duration API  public static Duration ping String host        Instant startTime   Instant now        try           InetAddress address   InetAddress getByName host           if  address isReachable 1000                 return Duration between startTime  Instant now                     catch  IOException e               Host not available  nothing to do here           return Duration ofDays 1

User · Answer

This should work   import java io BufferedReader  import java io InputStreamReader   public class Pinger    private static String keyWordTolookFor    average    public Pinger            TODO Auto-generated constructor stub      public static void main String   args       Test the ping method on Windows   System out println ping  192 168 0 1         public String ping String IP        try           String line          Process p   Runtime getRuntime   exec  ping -n 1     IP           BufferedReader input   new BufferedReader new InputStreamReader p getInputStream              while    line   input readLine       null                  if  line toLowerCase   indexOf keyWordTolookFor toLowerCase       -1                     String delims                           String   tokens   line split delims                   return tokens tokens length - 1                                     input close          catch  Exception err            err printStackTrace              return  Offline

User · Answer

On linux with oracle-jdk the code the OP submitted uses port 7 when not root and ICMP when root  It does do a real ICMP echo request when run as root as the documentation specifies   If you running this on a MS machine you may have to run the app as administrator to get the ICMP behaviour

User · Answer

Just an addition to what others have given  even though they work well but in some cases if internet is slow or some unknown network problem exists  some of the codes won t work  isReachable     But this code mentioned below creates a process which acts as a command line ping  cmd ping  to windows  It works for me in all cases  tried and tested   Code  -  public class JavaPingApp    public static void runSystemCommand String command         try           Process p   Runtime getRuntime   exec command           BufferedReader inputStream   new BufferedReader                  new InputStreamReader p getInputStream               String s                  reading output stream of the command         while   s   inputStream readLine       null                System out println s                    catch  Exception e            e printStackTrace             public static void main String   args         String ip    stackoverflow com     Any IP Address on your network   Web     runSystemCommand  ping     ip         Hope it helps  Cheers

User · Answer

I prefer to this way                        param host         return true means ping success false means ping fail          throws IOException         throws InterruptedException             private static boolean ping String host  throws IOException  InterruptedException           boolean isWindows   System getProperty  quot os name quot   toLowerCase   contains  quot win quot             ProcessBuilder processBuilder   new ProcessBuilder  quot ping quot   isWindows   quot -n quot     quot -c quot    quot 1 quot   host           Process proc   processBuilder start            return proc waitFor 200  TimeUnit MILLISECONDS          This way can limit the blocking time to the specific time such as 200 ms  It works well in MacOS Android and Windows  but should used in JDK 1 8   This idea comes from Mohammad Banisaeid but I can t comment   You must have 50 reputation to comment

User · Answer

I know this has been answered with previous entries  but for anyone else that comes to this question  I did find a way that did not require having use the  ping  process in windows and then scrubbing the output   What I did was use JNA to invoke Window s IP helper library to do an ICMP echo  See my own answer to my own similar issue

User · Answer

InetAddress is not always return correct value  It is successful in case of Local Host but for other hosts this shows that the host is unreachable  Try using ping command as given below   try       String cmd    cmd  C ping -n 1     ip       find   TTL                 Process myProcess   Runtime getRuntime   exec cmd       myProcess waitFor         if myProcess exitValue      0         return true            else           return false          catch  Exception e        e printStackTrace        return false

User · Answer

Here is a method for pinging an IP address in Java that should work on Windows and Unix systems   import org apache commons lang3 SystemUtils   import java io BufferedReader  import java io IOException  import java io InputStreamReader  import java util ArrayList  import java util List   public class CommandLine                   param ipAddress The internet protocol address to ping         return True if the address is responsive  false otherwise             public static boolean isReachable String ipAddress  throws IOException               List lt String gt  command   buildCommand ipAddress           ProcessBuilder processBuilder   new ProcessBuilder command           Process process   processBuilder start             try  BufferedReader standardOutput   new BufferedReader new InputStreamReader process getInputStream                            String outputLine               while   outputLine   standardOutput readLine       null                                   Picks up Windows and Unix unreachable hosts                 if  outputLine toLowerCase   contains  destination host unreachable                                          return false                                                     return true             private static List lt String gt  buildCommand String ipAddress                List lt String gt  command   new ArrayList lt  gt             command add  ping             if  SystemUtils IS OS WINDOWS                        command add  -n              else if  SystemUtils IS OS UNIX                        command add  -c              else                       throw new UnsupportedOperationException  Unsupported operating system                       command add  1            command add ipAddress            return command            Make sure to add Apache Commons Lang to your dependencies

User · Answer

You can not simply ping in Java as it relies on ICMP  which is sadly not supported in Java   http   mindprod com jgloss ping html  Use sockets instead  Hope it helps

[java] How to ping an IP address

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