Question

根据我收到的数据包，我正在尝试使用jnetpcap构建数据包我目前正在使用jnetpcap-1.4.r1425，并遇到了几个问题。

以下代码对我的所有问题都很常见：

JPacket wPacket = new JMemoryPacket(size);
wPacket.order(ByteOrder.BIG_ENDIAN);
wPacket.setUShort(12, 0x0800);
wPacket.scan(JProtocol.ETHERNET_ID);
wEth = wPacket.getHeader(new Ethernet());
wEth.source(sourceMac);
wEth.destination(destMac);
wEth.checksum(wEth.calculateChecksum());
headersize = 14;

wPacket.setUByte(14, 0x40 | 0x05);
wPacket.scan(JProtocol.ETHERNET_ID);
wIp4 = wPacket.getHeader(new Ip4());

if (packet.hasHeader(Icmp.ID))
  wIp4.type(Ip4.Ip4Type.ICMP);
else if (packet.hasHeader(Tcp.ID))
  wIp4.type(Ip4.Ip4Type.TCP);
else if (packet.hasHeader(Udp.ID))
  wIp4.type(Ip4.Ip4Type.UDP);

wIp4.length(500 - wEth.size());
wIp4.source(dIP);
wIp4.destination(sIP);
wIp4.ttl(32);
wIp4.flags(0);
wIp4.offset(0);
wIp4.checksum(wIp4.calculateChecksum());
headersize += 20;

尝试从上面的数据包中获取TCP标头，这使我无效

在上面的代码部分之后，我检查UDP / TCP / ICMP头的原始数据包 TCP的部分内容如下：

if (packet.hasHeader(Tcp.ID))
{
  wPacket.scan(JProtocol.ETHERNET_ID);
  wTcp = wPacket.getHeader(new Tcp());

  ......
}

这与UDP部分相同，但TCP部分错误。
结果是wTcp == null，我不知道为什么会这样出来。

ICMP校验和错误

公共部分的支票金额很好但是，ICMP校验和总是出错。

这就是我为ICMP所做的事情：

else if (packet.hasHeader(icmp) && icmp.hasSubHeader((new Icmp.EchoRequest())))
{
  wPacket.scan(JProtocol.ETHERNET_ID);
  wIcmp = wPacket.getHeader(new Icmp());
  wIcmp.setUByte(0, 0);
  wIcmp.setUByte(1, 0);
  JHeader[] tmp = {new Icmp.EchoReply()};
  wIcmp.setSubHeaders(tmp);
  wIcmp.checksum(wIcmp.calculateChecksum());
  headersize += 8 + 4;
}

如果有人能够指出我可能做错了什么，我将非常感激。

编辑：

toDebugString（）和hexdump（）无论问题是什么，都可以在这里找到，

JMemory: JMemory@7fd8a0c932d8class org.jnetpcap.packet.JPacket$State: size=304 bytes
JMemory: owner=packet.JScanner.class(size=631888/offset=529976)
JPacket.State#002: sizeof(packet_state_t)=184
JPacket.State#002: sizeof(header_t)=40 and *3=120
JPacket.State#002: pkt_header_map[0]=0x0000000000000007
JPacket.State#002: pkt_header_map[1]=0x0000000000000000
JPacket.State#002: pkt_header_map[2]=0x0000000000000000
JPacket.State#002: pkt_header_map[3]=0x0000000000000000
JPacket.State#002:         pkt_flags=0x00000000
JPacket.State#002:  pkt_header_count=3
JPacket.State#002:       pkt_wirelen=500 bytes
JPacket.State#002:        pkt_caplen=500 bytes
JPacket.State#002   : [         Protocol(ID/Flag) | Start | Prefix | Header | Gap | Payload | Postfix ]
JPacket.State#002[0]: [         ETHERNET( 1/0800) |     0 |      0 |     14 |   0 |     486 |       0 ]
JPacket.State#002[1]: [              IP4( 2/0800) |    14 |      0 |     20 |   0 |     466 |       0 ]
JPacket.State#002[2]: [          PAYLOAD( 0/0800) |    34 |      0 |    466 |   0 |       0 |       0 ]

0000:*68 01 00 5e  00 00 01 5f  93 48 01 04  08 00*45 00    h..^..._.H....E.
0010: 01 e6 00 00  00 00 20 06  1d 37 2d 37  80 71 3d f0    ...... ..7-7.q=.
0020: 90 43*13 c0  d8 7f 00 00  01 00 00 00  d8 7f 00 00    .C..............
0030: 02 00 00 00  74 2f 73 74  88 1e 13 c0  d8 7f 00 00    ....t/st........
0040: 00 00 00 00  6c 64 3b 3e  00 00 00 00  00 00 00 00    ....ld;>........
0050: 03 00 01 00  00 00 00 00  b5 00 00 00  00 00 00 00    ................
0060: 01 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00    ................
0070: 03 00 00 00  74 70 63 61  e0 1e 13 c0  d8 7f 00 00    ....tpca........
0080: 02 00 00 00  d8 7f 00 00  02 00 00 00  72 6d 61 74    ............rmat
0090: 88 1e 13 c0  d8 7f 00 00  00 00 00 00  75 6d 56 61    ............umVa
00a0: 00 00 00 00  00 00 00 00  03 00 01 00  00 00 00 00    ................
00b0: 19 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00    ................
00c0: 00 00 00 00  00 00 00 00  00 00 00 00  49 47 01 00    ............IG..
00d0: 00 00 00 00  00 00 00 00  00 00 00 00  d8 7f 00 00    ................
00e0: 02 00 00 00  6f 42 79 74  88 1e 13 c0  d8 7f 00 00    ....oByt........
00f0: 00 00 00 00  65 03 00 00  00 00 00 00  00 00 00 00    ....e...........
0100: 03 00 01 00  29 56 01 00  b8 00 00 00  00 00 00 00    ....)V..........
0110: 04 00 00 00  00 00 00 00  09 00 0b 00  00 00 00 00    ................
0120: 09 00 06 00  09 00 07 00  f0 1e 13 c0  d8 7f 00 00    ................
0130: 01 00 00 00  00 00 00 00  02 00 00 00  6f 6c 2f 6c    ............ol/l
0140: 88 1e 13 c0  d8 7f 00 00  00 00 00 00  45 74 68 65    ............Ethe
0150: 00 00 00 00  00 00 00 00  03 00 01 00  4c 6f 72 67    ............Lorg
0160: b5 00 00 00  d8 7f 00 00  05 00 00 00  00 00 00 00    ................
0170: 00 00 00 00  00 00 00 00  06 00 00 00  61 64 65 72    ............ader
0180: 00 1f 13 c0  d8 7f 00 00  03 00 00 00  72 67 2f 6a    ...........rg/j
0190: 02 00 00 00  63 61 70 2f  88 1e 13 c0  d8 7f 00 00    ....cap/........
01a0: 00 00 00 00  4e 31 30 4d  00 00 00 00  00 00 00 00    ....N10M........
01b0: 03 00 01 00  75 69 74 65  b1 00 00 00  6c 72 67 2f    ....uite....lrg/
01c0: 00 00 00 00  00 00 00 00  00 00 00 00  00 00 00 00    ................
01d0: 61 6e 6e 6f  74 61 74 65  00 00 00 00  00 00 00 00    annotate........
01e0: 00 00 00 00  74 65 3b 01  02 00 00 00  4e 01 00 03    ....te;.....N...
01f0: 1d 31 50 a2*                                          .1P.

最后的icmp数据包也是如此。

JMemory: JMemory@7fd8a0c94588class org.jnetpcap.packet.JPacket$State: size=344 bytes
JMemory: owner=packet.JScanner.class(size=631888/offset=534760)
JPacket.State#018: sizeof(packet_state_t)=184
JPacket.State#018: sizeof(header_t)=40 and *4=160
JPacket.State#018: pkt_header_map[0]=0x0000000000001007
JPacket.State#018: pkt_header_map[1]=0x0000000000000000
JPacket.State#018: pkt_header_map[2]=0x0000000000000000
JPacket.State#018: pkt_header_map[3]=0x0000000000000000
JPacket.State#018:         pkt_flags=0x00000000
JPacket.State#018:  pkt_header_count=4
JPacket.State#018:       pkt_wirelen=500 bytes
JPacket.State#018:        pkt_caplen=500 bytes
JPacket.State#018   : [         Protocol(ID/Flag) | Start | Prefix | Header | Gap | Payload | Postfix ]
JPacket.State#018[0]: [         ETHERNET( 1/0800) |     0 |      0 |     14 |   0 |     486 |       0 ]
JPacket.State#018[1]: [              IP4( 2/0800) |    14 |      0 |     20 |   0 |     466 |       0 ]
JPacket.State#018[2]: [             ICMP(12/0800) |    34 |      0 |      8 |   0 |     458 |       0 ]
JPacket.State#018[3]: [          PAYLOAD( 0/0800) |    42 |      0 |    458 |   0 |       0 |       0 ]

0000:*68 01 00 5e  00 00 01 5f  93 48 01 04  08 00*45 00    h..^..._.H....E.
0010: 01 e6 00 00  00 00 20 01  64 76 2d 37  80 71 58 c6    ...... .dv-7.qX.
0020: 2e 33*00 00  70 ed 00 00  00 00*00 00  00 00 53 87    .3..p.........S.
0030: 71 42 a6 f7  ad 57 f2 54  11 00 3e 61  ca 6e 49 b0    qB...W.T..>a.nI.
0040: a7 f7 59 4d  b7 42 5e 05  0a f4 65 f9  5a 25 46 98    ..YM.B^...e.Z%F.
0050: dc ed 5a d0  2f a7 39 4d  02 73 bd c9  9f 11 bc ab    ..Z./.9M.s......
0060: d2 70 34 9b  d0 be 15 9c  cc 88 3e 9e  4f f4 aa e3    .p4.......>.O...
0070: 98 b5 14 88  e8 2e f5 8b  16 f5 be 47  a1 e2 31 f9    ...........G..1.
0080: 82 68 d3 1e  d1 5d fb d0  b9 7f 95 63  0d f6 67 be    .h...].....c..g.
0090: 38 df 34 df  b5 48 65 f0  ff 79 82 79  72 6d 6b b0    8.4..He..y.yrmk.
00a0: 21 ee 69 6b  0f 0a ba f2  f5 52 d0 93  c2 66 b9 16    !.ik.....R...f..
00b0: 2f 67 dc 56  48 27 40 85  0c 4d b4 b5  2f 81 bf 43    /g.VH'@..M../..C
00c0: 58 f5 2b 9d  19 87 b0 3e  14 a6 f9 d3  3e f7 b0 ca    X.+....>....>...
00d0: 41 b1 73 05  89 6e 2c fb  6c 57 de 33  7f 5c 97 be    A.s..n,.lW.3.\..
00e0: c1 d9 d0 f5  53 60 70 83  3a a6 3e 54  1e 8e ae 4e    ....S`p.:.>T...N
00f0: 80 4b 24 7b  35 4e 48 f3  df 29 f1 c4  6e 5e f0 53    .K${5NH..)..n^.S
0100: 15 f7 18 89  1e 4d 41 93  26 8d 72 90  fa 83 ec a3    .....MA.&.r.....
0110: f8 d1 60 b6  63 49 a3 19  8c e3 c1 1b  20 b3 db 3c    ..`.cI...... ..<
0120: a4 cd 42 f9  53 ee 9d 86  7f f3 8b a0  c2 ff f4 9e    ..B.S...........
0130: a4 ce 58 28  e0 b9 c2 0f  13 bf 87 a5  85 91 ff e6    ..X(............
0140: 44 8c 93 43  33 b1 b4 ce  1c 02 22 19  9d da 28 7e    D..C3....."...(~
0150: 49 a6 84 c9  97 4a 1e 27  27 66 5d f2  b1 45 15 73    I....J.''f]..E.s
0160: 05 22 d6 9c  06 54 e7 17  2d 1d f6 7b  f5 3c 3a d0    ."...T..-..{.<:.
0170: 43 40 1e 3e  80 18 a3 eb  2d 2b c5 ad  7b 71 6b 83    C@.>....-+..{qk.
0180: 3f 2b d7 5d  19 01 4d fc  66 57 69 38  97 f8 b2 aa    ?+.]..M.fWi8....
0190: 79 1c a7 0a  b0 e5 33 7e  b9 ef 23 27  78 a3 62 5a    y.....3~..#'x.bZ
01a0: e7 26 e7 ff  ce 34 31 86  ad d6 01 3c  f8 7d 6c 30    .&...41....<.}l0
01b0: ed f7 62 d8  98 ce 21 bf  e2 cd 3e 6a  8e a2 f0 48    ..b...!...>j...H
01c0: 30 62 5b 29  ed ab 91 82  d2 56 e8 12  15 2d 17 68    0b[).....V...-.h
01d0: a9 f5 d4 c9  95 3d b7 48  ce 91 c3 e7  a4 92 1f 6d    .....=.H......m
01e0: e0 f1 0d ca  6a 67 a1 a3  60 22 6d 98  80 ac b7 62    ....jg..`"m....b
01f0: 03 7f 4a df*

Answer 1

我的建议是阅读并理解jnetpcap的作者编写的代码。

特别是从pcap文件读取数据并从头创建数据包的代码。基本上对等方是如何工作的。

Java =使用Jnetpcap从头开始构建数据包

1 个答案: