ngrep 是grep的网络版，他力求更多的grep特征，用于搜寻指定的数据包。由于安装ngrep需用到ibpcap库， 所以支持大量的操作系统和网络协议，能识别TCP、UDP和ICMP包。

安装ngrep
下载地址

选项

-h     is help/usage
-V    is version information
-q    is be quiet (don't print packet reception hash marks)静默模式，如果没有此开关，未匹配的数据包都以“#”显示
-e    is show empty packets 显示空数据包
-i     is ignore case 忽略大小写
-v    is invert match 反转匹配
-R   is don't do privilege revocation logic
-x    is print in alternate hexdump format 以16进制格式显示
-X   is interpret match expression as hexadecimal 以16进制格式匹配
-w   is word-regex (expression must match as a word) 整字匹配
-p   is don't go into promiscuous mode 不使用混杂模式
-l     is make stdout line buffered
-D   is replay pcap_dumps with their recorded time intervals
-t     is print timestamp every time a packet is matched在每个匹配的包之前显示时间戳
-T    is print delta timestamp every time a packet is matched显示上一个匹配的数据包之间的时间间隔
-M   is don't do multi-line match (do single-line match instead)仅进行单行匹配
-I     is read packet stream from pcap format file pcap_dump 从文件中读取数据进行匹配
-O   is dump matched packets in pcap format to pcap_dump 将匹配的数据保存到文件
-n    is look at only num packets 仅捕获指定数目的数据包进行查看
-A   is dump num packets after a match匹配到数据包后Dump随后的指定数目的数据包
-s    is set the bpf caplen
-S   is set the limitlen on matched packets
-W  is set the dump format (normal, byline, single, none) 设置显示格式byline将解析包中的换行符
-c    is force the column width to the specified size 强制显示列的宽度
-P   is set the non-printable display char to what is specified
-F   is read the bpf filter from the specified file 使用文件中定义的bpf(Berkeley Packet Filter)
-N   is show sub protocol number 显示由IANA定义的子协议号
-d   is use specified device (index) instead of the pcap default

应用举例：

捕获所有post请求(加个-W byline 参数后,将解析包中的换行符)：