Opening an adapter and capturing the packets

Obtain a packet capture handle (Pcap) with a specific network interface (adapter) to look at packets on the network and process it with Pcap.loop(int, PacketHandler, T args).

Once the adapter is opened, the capture can be started with Pcap.dispatch(int, PacketHandler, T args) or Pcap.dispatch(int, PacketHandler, T args). These two functions are very similar, the difference is that Pcap.dispatch(int, PacketHandler, T args) returns (although not guaranteed) when the timeout expires while Pcap.loop(int, PacketHandler, T args) doesn't return until maximum packets have been captured, so it can block for an arbitrary period on an under-utilized network.

Docs: libpcap, javadoc.

Java

public static void main(String[] _args)
    throws ErrorException, PermissionDeniedException, PromiscuousModePermissionDeniedException,
        TimestampPrecisionNotSupportedException, RadioFrequencyModeNotSupportedException,
        NoSuchDeviceException, ActivatedException, InterfaceNotUpException,
        InterfaceNotSupportTimestampTypeException {
  var service = Service.Creator.create("PcapService");
  try (var pcap = service.live(service.interfaces(), new DefaultLiveOptions())) {
    try {
      pcap.loop(
          10,
          (args, header, buffer) -> {
            System.out.println("Args     : " + args);
            System.out.println("Header   : " + header);
            System.out.println("Packet   : " + buffer);
          },
          "Hello pcap!");
    } catch (BreakException e) {
      System.err.println(e.getMessage());
    } catch (ErrorException e) {
      System.err.println(e.getMessage());
    }
  }
}

Kotlin

fun main() {
  val service = Service.Creator.create("PcapService")
  val pcap = service.live(service.interfaces(), DefaultLiveOptions())
  try {
    pcap.loop(
      10,
      { args: String, header: PacketHeader, buffer: PacketBuffer ->
        println("Args     : $args")
        println("Header   : $header")
        println("Packet   : $buffer")
      },
      "Hello pcap!"
    )
  } catch (e: BreakException) {
    System.err.println(e.message)
  } catch (e: ErrorException) {
    System.err.println(e.message)
  }
  pcap.close()
}

Scala

def main(_args: Array[String]): Unit = {
  val service = Service.Creator.create("PcapService")
  val pcap = service.live(service.interfaces().next(), new DefaultLiveOptions())
  try pcap.loop(10, (args: String, header: PacketHeader, buffer: PacketBuffer) => {
    println("Args     : ", args)
    println("Header   : ", header)
    println("Packet   : ", buffer)
  }, "Hello pcap!")
  catch {
    case e: BreakException =>
      System.err.println(e.getMessage)
    case e: ErrorException =>
      System.err.println(e.getMessage)
  }
  pcap.close()
}