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

　　代码如下:

　　git clone git://git.code.sf.net/p/ngrep/code ngrep-code

　　进入目录

　　代码如下:

　　cd ngrep-code

　　./configure --with-pcap-includes=/usr/local/include/pcap

　　make

　　make install

　　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)：

　　代码如下:

　　ranger@ranger:~$ sudo ngrep -q -W byline "(POST).*"

　　interface: eth0 (192.168.122.0/255.255.254.0)

　　match: (POST).*

　　T 192.168.122.74:46048 -> 140.207.228.58:80 [A]

　　POST /Hotel/OTA_HotelSearch.asmx?wsdl HTTP/1.1.

　　Content-Type: text/xml; charset=UTF-8.

　　SOAPAction: http://ctrip.com/Request.

　　Accept-Encoding: gzip, deflate.

　　Content-Length: 1330.

　　Accept: */*.

　　Accept-Language: zh-cn.

　　User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0).

　　UA-CPU: x86.

　　Accept-Encoding: gzip, deflate.

　　Connection: close.

　　Host: openapi.ctrip.com.

　　.

　　 <Request>

　　<Header AllianceID="***" SID="***" TimeStamp="1393554304685" RequestType="OTA_HotelSearch" Signature="B166CDF5422A6DA5BA81A08036E938E7"/>

　　<HotelRequest>

　　<RequestBody xmlns:ns="http://www.opentravel.org/OTA/2003/05" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

　　xmlns:xsd="http://www.w3.org/2001/XMLSchema">

　　<ns:OTA_HotelSearchRQ Version="1.0" PrimaryLangID="zh"

　　xsi:schemaLocation="http://www.opentravel.org/OTA/2003/05 OTA_HotelSearchRQ.xsd"