Linux命令(120)之tcpdump

linux命令之tcpdump

1.tcpdump介绍

linux命令tcpdump是用来将网络中传送的数据包完全截获下来以进行相关分析，常用的分析工具是wireshark

2.tcpdump用法

tcpdump [参数]

tcpdump常用关键字

3.实例

3.1.抓取ens33网络端口数据包，抓取100次并保存至root目录下

命令：

tcpdump -i ens33 -c 100 -w /root/ens33.cap

[root@rhel77 ~]# tcpdump -i ens33 -c 100 -w /root/ens33.cap
tcpdump: listening on ens33, link-type EN10MB (Ethernet), capture size 262144 bytes
100 packets captured
101 packets received by filter
0 packets dropped by kernel
[root@rhel77 ~]# ls -l ens33.cap    (使用wireshark进行分析)
-rw-r--r-- 1 tcpdump tcpdump 65910 Nov 13 09:54 ens33.cap
[root@rhel77 ~]# 

3.2.查看tcpdump帮助

命令：

man tcpdump

......
TCPDUMP(8)                                System Manager's Manual                                TCPDUMP(8)
 
NAME
       tcpdump - dump traffic on a network
 
SYNOPSIS
       tcpdump [ -AbdDefhHIJKlLnNOpqStuUvxX# ] [ -B buffer_size ]
               [ -c count ]
               [ -C file_size ] [ -G rotate_seconds ] [ -F file ]
               [ -i interface ] [ -j tstamp_type ] [ -m module ] [ -M secret ]
               [ --number ] [ -Q|-P in|out|inout ]
               [ -r file ] [ -V file ] [ -s snaplen ] [ -T type ] [ -w file ]
               [ -W filecount ]
 Manual page tcpdump(8) line 1 (press h for help or q to quit)
......