jpcap
Class Jpcap

java.lang.Object
  |
  +--jpcap.Jpcap

public class Jpcap

extends java.lang.Object

This class is used to capture packets.

Sample program

 import jpcap.*;

 class Tcpdump implements JpcapHandler
 {
   public void handlePacket(Packet packet){
     System.out.println(packet);
   }

   public static void main(String[] args) throws java.io.IOException{
     Jpcap jpcap=Jpcap.openDevice(args[0],1000,true,20);
     jpcap.processPacket(-1,new Tcpdump());
   }
 }
 

Field Summary

int	dropped_packets Number of dropped packets
int	received_packets Number of received packets

Method Summary

void	close() Closes the opened interface of dump file.
static java.lang.String[]	getDeviceDescription() Returns the descriptions of the interfaces (For Windows only)
static java.lang.String[]	getDeviceList() Returns the names of the interfaces that can be used for capturing.
java.lang.String	getErrorMessage() Returns an error message
Packet	getPacket() Returns a captured packet.
static java.lang.String	lookupDevice() Returns the names of the interfaces that can be used for capturing.
int	loopPacket(int count, JpcapHandler handler) Captures the specified number of packets consecutively.
static Jpcap	openDevice(java.lang.String device, int snaplen, boolean promisc, int to_ms) Initializes the network interface, and returns an instance of this class.
static Jpcap	openFile(java.lang.String filename) Opens a dump file created by tcpdump or Ethereal, and returns an instance of this class.
int	processPacket(int count, JpcapHandler handler) Captures the specified number of packets consecutively.
void	setFilter(java.lang.String condition, boolean optimize) Sets a filter.
void	updateStat() Updates received_packets and dropped_packets.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

received_packets

public int received_packets

Number of received packets

See Also:

updateStat()

dropped_packets

public int dropped_packets

Number of dropped packets

See Also:

updateStat()

Method Detail

openDevice

public static Jpcap openDevice(java.lang.String device,
                               int snaplen,
                               boolean promisc,
                               int to_ms)
                        throws java.io.IOException

Initializes the network interface, and returns an instance of this class.

Parameters:

device - Name of the network interface

snaplen - Max number of bytes captured at once

promisc - If true, the inferface becomes promiscuous mode

to_ms - Timeout of processPacket()

Returns:

an instance of this class Jpcap.

Throws:

java.io.IOException - Raised when the specified interface cannot be opened

openFile

public static Jpcap openFile(java.lang.String filename)
                      throws java.io.IOException

Opens a dump file created by tcpdump or Ethereal, and returns an instance of this class.

Parameters:

filename - File name of the dump file

Returns:

an instance of this class Jpcap

Throws:

java.io.IOException - If the file cannot be opened

lookupDevice

public static java.lang.String lookupDevice()

Returns the names of the interfaces that can be used for capturing.

Returns:

List of the interface names

getDeviceList

public static java.lang.String[] getDeviceList()

Returns the names of the interfaces that can be used for capturing.

Returns:

List of the interface names

getDeviceDescription

public static java.lang.String[] getDeviceDescription()

Returns the descriptions of the interfaces (For Windows only)

On Windows, the interface name is represented as a difficult string (e.g. \Device\Packet_{6E05D...}) This method returns the description of each interface that is easier to understand (e.g. 3com EtherLinkII).

Returns:

Descriptions of the interfaces

getPacket

public Packet getPacket()

Returns a captured packet.

Returns:

a captured packet

processPacket

public int processPacket(int count,
                         JpcapHandler handler)

Captures the specified number of packets consecutively.

Parameters:

count - Number of packets to be captured
You can specify -1 to capture packets parmanently until timeour, EOF or an error occurs.

handler - an instnace of JpcapHandler that analyzes the captured packets

Returns:

Number of captured packets

loopPacket

public int loopPacket(int count,
                      JpcapHandler handler)

Captures the specified number of packets consecutively.

Unlike processPacket(), this method ignores the timeout.

Parameters:

count - Number of packets to be captured
You can specify -1 to capture packets parmanently until EOF or an error occurs.

handler - an instnace of JpcapHandler that analyzes the captured packets

Returns:

Number of captured packets

setFilter

public void setFilter(java.lang.String condition,
                      boolean optimize)

Sets a filter. This filter is same as tcpdump.

Parameters:

condition - a string representation of the filter

optimize - If true, the filter is optimized

updateStat

public void updateStat()

Updates received_packets and dropped_packets.

getErrorMessage

public java.lang.String getErrorMessage()

Returns an error message

Returns:

error message

close

public void close()

Closes the opened interface of dump file.