I have my below code which can captures packets from the interface using pcap4j but I am not sure how can I print the request and the response data present in the packet. For example, if I make a REST call from a postman then I want to trace the request and response. This is the same as Wireshark. I am stuck in the last part where I am able to capture the packet but not sure how do I read the packet contents which I can print on console.
try {
InetAddress addr = InetAddress.getByName("10.227.178.25");
PcapNetworkInterface device = Pcaps.getDevByAddress(addr);
System.out.println("You chose: " + device);
int snapshotLength = 64 * 1024; // in bytes
int readTimeout = 50; // in milliseconds
final PcapHandle handle;
handle = device.openLive(snapshotLength, PromiscuousMode.PROMISCUOUS, readTimeout);
String filter = "tcp port 80";
handle.setFilter(filter, BpfCompileMode.OPTIMIZE);
// Create a listener that defines what to do with the received packets
PacketListener listener = new PacketListener() {
@Override
public void gotPacket(Packet packet) {
// Override the default gotPacket() function and process packet
System.out.println(handle.getTimestamp());
System.out.println(packet);
byte[] b = packet.getRawData();
Packet p = packet.getPayload();
}
};
// Tell the handle to loop using the listener we created
try {
int maxPackets = 50;
handle.loop(maxPackets, listener);
} catch (InterruptedException e) {
e.printStackTrace();
}
// Cleanup when complete
handle.close();
}catch(Exception e) {
e.printStackTrace();
}
So I have two questions :
- How can I capture the HTTP request and response and print it on the console.
- How can I let the java code run continuously such that it keeps on capturing the packets.
I did check the pcap4j documents but not sure how I can read the packet contents where I can read the HTTP request and HTTP response.
