Linux tcpdump命令用于傾倒網絡傳輸數據。

執行tcpdump指令可列出經過指定網絡界面的數據包文件頭，在Linux操作系統中，你必須是系統管理員。

語法

tcpdump [-adeflnNOpqStvx][-c][-dd][-ddd][-F][-i][-r][-s][-tt][-T][-vv][-w][輸出數據欄位]

參數說明：

-a 嘗試將網絡和廣播地址轉換成名稱。

-c 收到指定的數據包數目后，就停止進行傾倒操作。

-d 把編譯過的數據包編碼轉換成可閱讀的格式，并傾倒到標準輸出。

-dd 把編譯過的數據包編碼轉換成C語言的格式，并傾倒到標準輸出。

-ddd 把編譯過的數據包編碼轉換成十進制數字的格式，并傾倒到標準輸出。

-e 在每列傾倒資料上顯示連接層級的文件頭。

-f 用數字顯示網際網絡地址。

-F 指定內含表達方式的文件。

-i 使用指定的網絡截面送出數據包。

-l 使用標準輸出列的緩沖區。

-n 不把主機的網絡地址轉換成名字。

-N 不列出

實例

顯示TCP包信息

# tcpdump

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes

23:35:55.129998 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 148872068:148872168(100) ack 4184371747 win 2100

23:35:55.182357 IP 192.168.0.1.2101 > 192.168.0.3.ssh: . ack 100 win 64240

23:35:55.182397 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 100:200(100) ack 1 win 2100

23:35:55.131713 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 50226+ PTR? 1.0.168.192.in-addr.arpa. (42)

23:35:55.131896 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 50226+ PTR? 1.0.168.192.in-addr.arpa. (42)

23:35:55.154238 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64215: 50226 NXDomain 0/0/0 (42)

23:35:55.156298 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: 50226 NXDomain 0/0/0 (42)

23:35:55.159292 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 30304+ PTR? 3.0.168.192.in-addr.arpa. (42)

23:35:55.159449 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 30304+ PTR? 3.0.168.192.in-addr.arpa. (42)

23:35:55.179816 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64215: 30304 NXDomain 0/0/0 (42)

23:35:55.181279 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: 30304 NXDomain 0/0/0 (42)

23:35:55.181806 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 200:268(68) ack 1 win 2100

23:35:55.182177 IP 192.168.0.1.2101 > 192.168.0.3.ssh: . ack 268 win 64198

23:35:55.182677 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 43983+ PTR? 112.96.103.202.in-addr.arpa. (45)

23:35:55.182807 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 43983+ PTR? 112.96.103.202.in-addr.arpa. (45)

23:35:55.183055 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 268:352(84) ack 1 win 2100

23:35:55.201096 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64215: 43983 1/0/0 (72)

23:35:55.203087 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: 43983 1/0/0 (72)

23:35:55.204666 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 352:452(100) ack 1 win 2100

23:35:55.204852 IP 192.168.0.1.2101 > 192.168.0.3.ssh: . ack 452 win 64152

23:35:55.205305 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 452:520(68) ack 1 win 2100

23:35:55.205889 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 9318+ PTR? 85.6.250.118.in-addr.arpa. (43)

23:35:55.206071 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 9318+ PTR? 85.6.250.118.in-addr.arpa. (43)

23:35:55.215338 PPPoE [ses 0x1cb0] IP 115.238.1.45.3724 > 118.250.6.85.64120: P 2392751922:2392751987(65) ack 2849759785 win 54

23:35:55.216273 IP 115.238.1.45.3724 > 192.168.0.65.2057: P 2392751922:2392751987(65) ack 2849759785 win 54

23:35:55.329204 IP 192.168.0.1.2101 > 192.168.0.3.ssh: . ack 520 win 64135

23:35:55.458214 IP 192.168.0.65.2057 > 115.238.1.45.3724: . ack 65 win 32590

23:35:55.458221 PPPoE [ses 0x1cb0] IP 118.250.6.85.64120 > 115.238.1.45.3724: . ack 65 win 32590

23:35:55.708228 PPPoE [ses 0x1cb0] IP 115.238.1.45.3724 > 118.250.6.85.64120: P 65:118(53) ack 1 win 54

23:35:55.710213 IP 115.238.1.45.3724 > 192.168.0.65.2057: P 65:118(53) ack 1 win 54

23:35:55.865151 IP 192.168.0.65.2057 > 115.238.1.45.3724: . ack 118 win 32768

23:35:55.865157 PPPoE [ses 0x1cb0] IP 118.250.6.85.64120 > 115.238.1.45.3724: . ack 118 win 32768

23:35:56.242805 IP 192.168.0.65.2057 > 115.238.1.45.3724: P 1:25(24) ack 118 win 32768

23:35:56.242812 PPPoE [ses 0x1cb0] IP 118.250.6.85.64120 > 115.238.1.45.3724: P 1:25(24) ack 118 win 32768

23:35:56.276816 PPPoE [ses 0x1cb0] IP 115.238.1.45.3724 > 118.250.6.85.64120: . ack 25 win 54

23:35:56.278240 IP 115.238.1.45.3724 > 192.168.0.65.2057: . ack 25 win 54

23:35:56.349747 PPPoE [ses 0x1cb0] IP 115.238.1.45.3724 > 118.250.6.85.64120: P 118:159(41) ack 25 win 54

23:35:56.351780 IP 115.238.1.45.3724 > 192.168.0.65.2057: P 118:159(41) ack 25 win 54

23:35:56.400051 PPPoE [ses 0x1cb0] IP 119.147.18.44.8000 > 118.250.6.85.4000: UDP, length 79

23:35:56.475050 IP 192.168.0.65.2057 > 115.238.1.45.3724: . ack 159 win 32762

23:35:56.475063 PPPoE [ses 0x1cb0] IP 118.250.6.85.64120 > 115.238.1.45.3724: . ack 159 win 32762

23:35:56.508968 PPPoE [ses 0x1cb0] IP 115.238.1.45.3724 > 118.250.6.85.64120: P 159:411(252) ack 25 win 54

23:35:56.510182 IP 115.238.1.45.3724 > 192.168.0.65.2057: P 159:411(252) ack 25 win 54

23:35:56.592028 PPPoE [ses 0x1cb0] IP 117.136.2.43.38959 > 118.250.6.85.63283: UDP, length 36

44 packets captured

76 packets received by filter

0 packets dropped by kernel

顯示指定數量包

# tcpdump -c 20

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes

23:36:28.949538 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 148875984:148876020(36) ack 4184373187 win 2100

23:36:28.994325 IP 192.168.0.1.2101 > 192.168.0.3.ssh: . ack 36 win 64020

23:36:28.994368 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 36:72(36) ack 1 win 2100

23:36:28.950779 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 18242+ PTR? 1.0.168.192.in-addr.arpa. (42)

23:36:28.950948 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 18242+ PTR? 1.0.168.192.in-addr.arpa. (42)

23:36:28.960105 PPPoE [ses 0x1cb0] IP 222.82.119.41.13594 > 118.250.6.85.63283: UDP, length 36

23:36:28.962192 IP 222.82.119.41.13594 > 192.168.0.65.13965: UDP, length 36

23:36:28.963118 IP 192.168.0.65.13965 > 222.82.119.41.13594: UDP, length 34

23:36:28.963123 PPPoE [ses 0x1cb0] IP 118.250.6.85.63283 > 222.82.119.41.13594: UDP, length 34

23:36:28.970185 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64215: 18242 NXDomain 0/0/0 (42)

23:36:28.970413 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: 18242 NXDomain 0/0/0 (42)

23:36:28.972352 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: 17862+ PTR? 3.0.168.192.in-addr.arpa. (42)

23:36:28.972474 PPPoE [ses 0x1cb0] IP 118.250.6.85.64215 > dns2.cs.hn.cn.domain: 17862+ PTR? 3.0.168.192.in-addr.arpa. (42)

23:36:28.982287 PPPoE [ses 0x1cb0] IP 121.12.131.163.13109 > 118.250.6.85.63283: UDP, length 27

23:36:28.984162 IP 121.12.131.163.13109 > 192.168.0.65.13965: UDP, length 27

23:36:28.985021 IP 192.168.0.65.13965 > 121.12.131.163.13109: UDP, length 103

23:36:28.985027 PPPoE [ses 0x1cb0] IP 118.250.6.85.63283 > 121.12.131.163.13109: UDP, length 103

23:36:28.991919 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64215: 17862 NXDomain 0/0/0 (42)

23:36:28.993142 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: 17862 NXDomain 0/0/0 (42)

23:36:28.993574 IP 192.168.0.3.ssh > 192.168.0.1.2101: P 72:140(68) ack 1 win 2100

20 packets captured

206 packets received by filter

129 packets dropped by kernel

精簡顯示

# tcpdump -c 10 -q //精簡模式顯示 10個包

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes

23:43:05.792280 IP 192.168.0.3.ssh > 192.168.0.1.2101: tcp 36

23:43:05.842115 IP 192.168.0.1.2101 > 192.168.0.3.ssh: tcp 0

23:43:05.845074 IP 115.238.1.45.3724 > 192.168.0.65.2057: tcp 0

23:43:05.907155 IP 192.168.0.3.ssh > 192.168.0.1.2101: tcp 36

23:43:05.793880 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: UDP, length 42

23:43:05.794076 PPPoE [ses 0x1cb0] IP 118.250.6.85.64219 > dns2.cs.hn.cn.domain: UDP, length 42

23:43:05.811127 PPPoE [ses 0x1cb0] IP dns2.cs.hn.cn.domain > 118.250.6.85.64219: UDP, length 42

23:43:05.814764 IP dns2.cs.hn.cn.domain > 192.168.0.3.32804: UDP, length 42

23:43:05.816404 IP 192.168.0.3.32804 > dns2.cs.hn.cn.domain: UDP, length 42

23:43:05.816545 PPPoE [ses 0x1cb0] IP 118.250.6.85.64219 > dns2.cs.hn.cn.domain: UDP, length 42

10 packets captured

39 packets received by filter

0 packets dropped by kernel

轉換克閱讀格式

# tcpdump -d

(000) ret #96

轉換成十進制格式

# tcpdump -ddd

1

6 0 0 96

總結

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