Linux使用tcpdump命令抓包保存pcap文件wireshark分析

[root@ok Desktop]# yum search tcpdump
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors.yun-idc.com
 * extras: mirrors.yun-idc.com
 * updates: mirrors.yun-idc.com
======================================================================= N/S Matched: tcpdump ========================================================================
tcpdump.x86_64 : A network traffic monitoring tool

  Name and summary matches only, use "search all" for everything.
[root@ok Desktop]# which tcpdump
/usr/sbin/tcpdump
[root@ok Desktop]# tcpdump -h
tcpdump version 4.1-PRE-CVS_2015_07_23
libpcap version 1.4.
Usage: tcpdump [-aAdDefhIJKlLnNOpqRStuUvxX] [ -B size ] [ -c count ]
        [ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]
        [ -i interface ] [ -j tstamptype ] [ -M secret ]
        [ -P in|out|inout ]
        [ -r file ] [ -s snaplen ] [ -T type ] [ -w file ]
        [ -W filecount ] [ -y datalinktype ] [ -z command ]
        [ -Z user ] [ expression ]

[root@ok Desktop]# yum search wireshark
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors.yun-idc.com
 * extras: mirrors.yun-idc.com
 * updates: mirrors.yun-idc.com
================================================ N/S Matched: wireshark ================================================
wireshark-devel.i686 : Development headers and libraries for wireshark
wireshark-devel.x86_64 : Development headers and libraries for wireshark
wireshark-gnome.x86_64 : Gnome desktop integration for wireshark and wireshark-usermode
wireshark.i686 : Network traffic analyzer
wireshark.x86_64 : Network traffic analyzer

  Name and summary matches only, use "search all" for everything.

安装：

[root@ok Desktop]# yum install wireshark* -y
[root@ok Desktop]# which wireshark
/usr/sbin/wireshark
[root@ok Desktop]# rpm -qa|grep wireshark
wireshark-devel-1.8.10-17.el6.x86_64
wireshark-1.8.10-17.el6.x86_64
wireshark-gnome-1.8.10-17.el6.x86_64

保存tcpdump抓包结果

[root@bass Desktop]# tcpdump -i eth0 -w dump.pcap
-i #是指定要抓取的网卡
-w #指定结果保存的位置
[root@bass Desktop]# tcpdump -i eth0 -w dump.pcap -v
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size  bytes
^C189 packets captured
 packets received by filter
 packets dropped by kernel
－v＃主要是为了得到Got 15这个数，当想要停止的时候，按下ctrl + c
[root@bass Desktop]# ll -h dump.pcap
-rw-r--r--.  tcpdump tcpdump 18K Aug  : dump.pcap

在wireshark中打开：

[root@bass Desktop]# wireshark dump.pcap ＃linux下查看

我们用tcpdump抓包的时候，默认是显示这样的：

上图中标出三快区域，红色框内，是用来显示简单的数据包信息，我们用tcpdump抓包如时候，默认情况是显示成这样的；深蓝框内，是用来显示选中的数据包的详细信息，是按照TCP/IP四层结构显示的，第一行是数据链路层的信息，第二行是网络层信息（IP协议），第三行是传输层信息（TCP协议），第四层是应用层信息（HTTP协议），可以展开第一行用来观察具体的内容；最后一个区域淡蓝色框中，是用来显示此数据包的真实面目。（下图列清楚）

------------------------------------------------------------------------------------------------------------------------------------------------------

sh-4.1# tcpdump -i eth0 -c  -w 20gebao -v
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size  bytes
 packets captured
 packets received by filter
 packets dropped by kernel

使用-c参数指定要监听到的数据包数量