hi guys,

I am new to network programming,dealing with sockets(bsd)
I want to know what all other ACTIVE systems present on network.how to code??approach is enough please throw ur ideas

my thought: i will act as client & 'connect' to rest of systems
...every other system should work as server and 'accept'my request
if so
i will make a count of active systems present on network

define what you mean by "active" and "connect" please...

hi

"connect" is a system call in linux which the client side program uses to connect to a known server
"accept" is also a system call but from server side to hear a request from client.

practical implementation of my code:
In hospital every bed has a patient monitoring system and all the systems r in a local network
every system should know what all other systems r present in the network

so this isn't a case of just finding all machines on a network, but all instances of a given tcp service listening on a certain port... wouldn't really know much about that to be honest, not without port scanning, which is pretty crude. better off in the Programming forum really, moving it there now.

my first thought when reading this was port scanner


will you be trying all well known ports.
or a significant few?

You may want to look at the source code for nmap


doing nmap -sP 192.168.0.0/24 for example

will do a ping scan on every machine on the subnet and then print out the available machines.
This obviously uses an icmp echo requestand I gather from eading the man page for nmap it also sends a tcp packet to port 80 using connect() as well.

public class findNo{

public static void main(String a[])
{

String s=a[0];
int OneCount=0;
int ZeroCount=0;
for(int i=0;i<s.length();i++)
{
int j=i+1;
String temp=s.substring(i,j);
if(temp.equals("1"))
{
OneCount++;
}
if(temp.equals("0"))
{
ZeroCount++;
}
}
System.out.println("OneCount ++++++++"+OneCount);
System.out.println("ZeroCount ++++++++"+ZeroCount);
}
}
-----------------------------------

public class StringReverse{

public static void main(String arg[]){

String s=arg[0];
String retun="";
for(int i=0;i<s.length();i++)
{
int j=i+1;
String temp=s.substring(i,j);
retun=temp+retun;
System.out.println("String >>>>>. "+retun);
}
}
}

------------------------------------
import java.util.StringTokenizer;
import java.util.*;
import java.io.*;

public class StringMatching{


public static void main(String a[]) throws IOException {

Vector v=new Vector();
Vector sample=new Vector();
Vector count=new Vector();
BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the Data : ");
String s=bf.readLine();
// String s="the animal is so big, big animal can run fast so we should take care";
StringTokenizer temp=new StringTokenizer(s," ");

while(temp.hasMoreElements())
{
v.add(temp.nextToken());
}
for(int i=0;i<v.size(); i++)
{
String match1=(String)v.elementAt(i);
if(!sample.contains(match1))
{
sample.add(match1);
System.out.print("the word >>>>"+match1);
int Count=0;
for(int j=0;j<v.size();j++)
{
if(v.elementAt(j).equals(match1))
{
Count++;
}

}
System.out.println(" ---------"+Count);
}
}
}
}

--------------------------------------------------------------


execution:

first compile all:
and run like

java findNo 123101
java StringReverse asdfg
java StringMatching