python-dpkt : ICMP packet parsing

Question

如何解析 ICMP 数据包(使用 dpkt)来检查它是从 A 到 B 的请求还是响应？

我找到了一些 TCP 和 UDP 数据包的示例(如下)，但我找不到 IP 数据包的任何内容。

import dpkt

f = open('test.pcap')
pcap = dpkt.pcap.Reader(f)

for ts, buf in pcap:
    eth = dpkt.ethernet.Ethernet(buf)
    ip = eth.data
    tcp = ip.data

    if tcp.dport == 80 and len(tcp.data) > 0:
        http = dpkt.http.Request(tcp.data)
        print http.uri

f.close()

另外，dpkt 有什么好的教程吗？

Answer 1

这是一个老问题，但对于遇到这个问题的人来说，我已经在 dpkt 存储库中添加了一个 ICMP 示例。文档可以在这里找到:http://dpkt.readthedocs.io/en/latest/print_icmp.html，示例代码可以在 dpkt/examples/print_icmp.py 中找到

# For each packet in the pcap process the contents
for timestamp, buf in pcap:

    # Unpack the Ethernet frame (mac src/dst, ethertype)
    eth = dpkt.ethernet.Ethernet(buf)

    # Make sure the Ethernet data contains an IP packet
    if not isinstance(eth.data, dpkt.ip.IP):
        print 'Non IP Packet type not supported %s\n' % eth.data.__class__.__name__
        continue

    # Now grab the data within the Ethernet frame (the IP packet)
    ip = eth.data

    # Now check if this is an ICMP packet
    if isinstance(ip.data, dpkt.icmp.ICMP):
        icmp = ip.data

        # Pull out fragment information
        do_not_fragment = bool(ip.off & dpkt.ip.IP_DF)
        more_fragments = bool(ip.off & dpkt.ip.IP_MF)
        fragment_offset = ip.off & dpkt.ip.IP_OFFMASK

        # Print out the info
        print 'Timestamp: ', str(datetime.datetime.utcfromtimestamp(timestamp))
        print 'Ethernet Frame: ', mac_addr(eth.src), mac_addr(eth.dst), eth.type
        print 'IP: %s -> %s   (len=%d ttl=%d DF=%d MF=%d offset=%d)' % \
              (inet_to_str(ip.src), inet_to_str(ip.dst), ip.len, ip.ttl, 
              do_not_fragment, more_fragments, fragment_offset)
        print 'ICMP: type:%d code:%d checksum:%d data: %s\n' % (icmp.type, 
               icmp.code, icmp.sum, repr(icmp.data))

示例输出

Timestamp:  2013-05-30 22:45:17.283187
Ethernet Frame:  60:33:4b:13:c5:58 02:1a:11:f0:c8:3b 2048
IP: 192.168.43.9 -> 8.8.8.8   (len=84 ttl=64 DF=0 MF=0 offset=0)
ICMP: type:8 code:0 checksum:48051 data: Echo(id=55099, data='Q\xa7\xd6}\x00\x04Q\xe4\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./01234567')

Timestamp:  2013-05-30 22:45:17.775391
Ethernet Frame:  02:1a:11:f0:c8:3b 60:33:4b:13:c5:58 2048
IP: 8.8.8.8 -> 192.168.43.9   (len=84 ttl=40 DF=0 MF=0 offset=0)
ICMP: type:0 code:0 checksum:50099 data: Echo(id=55099, data='Q\xa7\xd6}\x00\x04Q\xe4\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./01234567')