Tcpdump usage examples

In most cases you will need root permission to be able to capture packets on an interface. Using tcpdump (with root) to capture the packets and saving them to a file to analyze with Wireshark (using a regular account) is recommended over using Wireshark with a root account to capture packets on an "untrusted" interface. See the Wireshark security advisories for reasons why.

See the list of interfaces on which tcpdump can listen:

tcpdump -D

Listen on interface eth0:

tcpdump -i eth0

Listen on any available interface (cannot be done in promiscuous mode. Requires Linux kernel 2.2 or greater):

tcpdump -i any

Be verbose while capturing packets:

tcpdump -v

Be more verbose while capturing packets:

tcpdump -vv

Be very verbose while capturing packets:

tcpdump -vvv

Be verbose and print the data of each packet in both hex and ASCII, excluding the link level header:

tcpdump -v -X

Be verbose and print the data of each packet in both hex and ASCII, also including the link level header:

tcpdump -v -XX

Be less verbose (than the default) while capturing packets:

tcpdump -q

Limit the capture to 100 packets:

tcpdump -c 100

Record the packet capture to a file called capture.cap:

tcpdump -w capture.cap

Record the packet capture to a file called capture.cap but display on-screen how many packets have been captured in real-time:

tcpdump -v -w capture.cap

Display the packets of a file called capture.cap:

tcpdump -r capture.cap

Display the packets using maximum detail of a file called capture.cap:

tcpdump -vvv -r capture.cap

Display IP addresses and port numbers instead of domain and service names when capturing packets (note: on some systems you need to specify -nn to display port numbers):

tcpdump -n

Capture any packets where the destination host is 192.168.1.1. Display IP addresses and port numbers:

tcpdump -n dst host 192.168.1.1

Capture any packets where the source host is 192.168.1.1. Display IP addresses and port numbers:

tcpdump -n src host 192.168.1.1

Capture any packets where the source or destination host is 192.168.1.1. Display IP addresses and port numbers:

tcpdump -n host 192.168.1.1

Capture any packets where the destination network is 192.168.1.0/24. Display IP addresses and port numbers:

tcpdump -n dst net 192.168.1.0/24

Capture any packets where the source network is 192.168.1.0/24. Display IP addresses and port numbers:

tcpdump -n src net 192.168.1.0/24

Capture any packets where the source or destination network is 192.168.1.0/24. Display IP addresses and port numbers:

tcpdump -n net 192.168.1.0/24

Capture any packets where the destination port is 23. Display IP addresses and port numbers:

tcpdump -n dst port 23

Capture any packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:

tcpdump -n dst portrange 1-1023

Capture only TCP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:

tcpdump -n tcp dst portrange 1-1023

Capture only UDP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:

tcpdump -n udp dst portrange 1-1023

Capture any packets with destination IP 192.168.1.1 and destination port 23. Display IP addresses and port numbers:

tcpdump -n "dst host 192.168.1.1 and dst port 23"

Capture any packets with destination IP 192.168.1.1 and destination port 80 or 443. Display IP addresses and port numbers:

tcpdump -n "dst host 192.168.1.1 and (dst port 80 or dst port 443)"

Capture any ICMP packets:

tcpdump -v icmp

Capture any ARP packets:

tcpdump -v arp

Capture either ICMP or ARP packets:

tcpdump -v "icmp or arp"

Capture any packets that are broadcast or multicast:

tcpdump -n "broadcast or multicast"

Capture 500 bytes of data for each packet rather than the default of 68 bytes:

tcpdump -s 500

Capture all bytes of data within the packet:

tcpdump -s 0
 
http://www.rationallyparanoid.com/articles/tcpdump.html

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tcpdump 的抓包保存到文件的命令参数是-w xxx.cap

 

抓eth1的包 

tcpdump -i eth1 -w /tmp/xxx.cap 

 

抓 192.168.1.123的包 

tcpdump -i eth1 host 192.168.1.123 -w /tmp/xxx.cap 

 

抓192.168.1.123的80端口的包 

tcpdump -i eth1 host 192.168.1.123 and port 80 -w /tmp/xxx.cap 

 

抓192.168.1.123的icmp的包 

tcpdump -i eth1 host 192.168.1.123 and icmp -w /tmp/xxx.cap 

 

抓192.168.1.123的80端口和110和25以外的其他端口的包 

tcpdump -i eth1 host 192.168.1.123 and ! port 80 and ! port 25 and ! port 110 -w /tmp/xxx.cap 

 

抓vlan 1的包 

tcpdump -i eth1 port 80 and vlan 1 -w /tmp/xxx.cap 

 

抓pppoe的密码 

tcpdump -i eth1 pppoes -w /tmp/xxx.cap 

 

 

以100m大小分割保存文件， 超过100m另开一个文件 -C 100m 

 

抓10000个包后退出 -c 10000 

 

后台抓包， 控制台退出也不会影响： 

nohup tcpdump -i eth1 port 110 -w /tmp/xxx.cap & 

 

抓下来的文件可以直接用ethereal 或者wireshark打开。

 

http://liuzhigong.blog.163.com/blog/static/1782723752012851043396/

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linux下使用tcpdump抓包数据不完整问题解决方法

 linux下使用tcpdump抓包数据长度显示不全的问题，如图1所示，实际数据长度应该是76但只抓到了24字节的数据：

 

 

 

 

这是因为tcpdump命令默认捕获包总长度是96字节，如图所示，我们只要在抓包命令里加一个参数-s0即可捕获完整数据的数据包

 

 

 

命令：tmpdump -s0 -i any port 6024 -w /tmp/a.pcap

-s0, 表示取消抓包长度限制

-i any, 表示在所有网卡设备上抓包，也可单独指定某个网卡，如-i eth0

port 6024, 表示在哪个端口上抓包

-w /tmp/a.pcap, 表示抓包文件存储路径

http://liuzhigong.blog.163.com/blog/static/1782723752012851043396/