JNetPcap 捕获包没有返回 IP

Question

我从这里得到了这段代码 https://javatutorial.net/capture-network-packages-java 但它不 return src 或目标 ips。我可以通过

查看 ip

            System.out.println("packet.getHeader(ip)");
            System.out.println(packet.getHeader(ip));

Ip: ******* Ip4 - "ip version 4" - offset=14 (0xE) length=20 protocol suite=NETWORK

IP:

ip:版本=4

Ip: hlen = 5 [5 * 4 = 20 字节，无 Ip 选项]

Ip: diffserv = 0x0 (0)

Ip: 0000 00.. = [0] code point: not set

IP：.... ..0。 = [0] ECN 位：未设置

IP：.... ...0 = [0] ECE 位：未设置

IP：长度=137

IP:id = 0xC22C (49708)

Ip: 标志 = 0x2 (2)

IP: 0.. = [0] 保留

IP：.1。 = [1] DF: 不分片: set

Ip: ..0 = [0] MF: 更多片段: 未设置

Ip: 偏移量 = 0

Ip: ttl = 62 [生存时间]

Ip: type = 6 [next: Transmission Control]

Ip: 校验和 = 0xF22E (61998) [正确]

IP: 来源 = 10.222.82.222

IP: 目的地 = 10.222.82.224

IP:

我做错了什么？

`import java.util.ArrayList;
 import java.util.List;
 import org.jnetpcap.Pcap;
 import org.jnetpcap.PcapIf;
 import org.jnetpcap.packet.PcapPacket;
 import org.jnetpcap.packet.PcapPacketHandler;
 import org.jnetpcap.protocol.network.Ip4;
public class PackageCapture {
public static void main(String[] args) {
    List<PcapIf> alldevs = new ArrayList<PcapIf>(); // Will be filled with NICs
    StringBuilder errbuf = new StringBuilder(); // For any error msgs
    int r = Pcap.findAllDevs(alldevs, errbuf);
    if (r != Pcap.OK || alldevs.isEmpty()) {
        System.err.printf("Can't read list of devices, error is %s",
                errbuf.toString());
        return;
    }
    System.out.println("Network devices found:");
    int i = 0;
    for (PcapIf device : alldevs) {
        String description = (device.getDescription() != null) ? device
                .getDescription() : "No description available";
        System.out.printf("#%d: %s [%s]\n", i++, device.getName(),
                description);
    }
    PcapIf device = alldevs.get(0); // Get first device in list
    System.out.printf("\nChoosing '%s' on your behalf:\n",
            (device.getDescription() != null) ? device.getDescription()
                    : device.getName());
    int snaplen = 64 * 1024; // Capture all packets, no trucation
    int flags = Pcap.MODE_PROMISCUOUS; // capture all packets
    int timeout = 10 * 1000; // 10 seconds in millis
    Pcap pcap = Pcap.openLive(device.getName(), snaplen, flags, timeout, errbuf);
    if (pcap == null) {
        System.err.printf("Error while opening device for capture: "
                + errbuf.toString());
        return;
    }
    PcapPacketHandler<String> jpacketHandler = new PcapPacketHandler<String>() {
        public void nextPacket(PcapPacket packet, String user) {
            byte[] data = packet.getByteArray(0, packet.size()); // the package data
            byte[] sIP = new byte[4];
            byte[] dIP = new byte[4];
            Ip4 ip = new Ip4();
            if (packet.hasHeader(ip) == false) {
                return; // Not IP packet
            }
            ip.source(sIP);
            ip.destination(dIP);
            /* Use jNetPcap format utilities */
            String sourceIP = 
     org.jnetpcap.packet.format.FormatUtils.ip(sIP);
                String destinationIP = 
     org.jnetpcap.packet.format.FormatUtils.ip(dIP);

            System.out.println("srcIP=" + sourceIP + 
                    " dstIP=" + destinationIP + 
                    " caplen=" + packet.getCaptureHeader().caplen());
        }
    };
    // capture first 10 packages
    pcap.loop(10, jpacketHandler, "jNetPcap");
    pcap.close();
}
}`

Answer 1

很简单，他们更改了代码。而不是

ip.source(sIP); ip.destination(dIP);

做

sIP = ip.source(); dIP = ip.destination();

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