ngrep命令用法
<p>ngrep 是grep(在文本中搜索字符串的工具)的网络版，他力求更多的grep特征，用于搜寻指定的数据包。正由于安装ngrep需用到libpcap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，理解bpf的过滤机制。</p><h3>语法</h3>
<p></p><pre class="brush:bash;toolbar:false">ngrep <-LhNXViwqpevxlDtTRM> <-IO pcap_dump> <-n num> <-d dev> <-A num>
<-s snaplen> <-S limitlen> <-W normal|byline|single|none> <-c cols>
<-P char> <-F file> <match expression> <bpf filter></pre><p></p>
<h3>选项</h3>
<p></p><pre class="brush:bash;toolbar:false">-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
-Wis 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</pre><p>Allowable primitives are:<br><strong>dst host </strong>host<br>
True if the IP destination field of the packet is host, which may be either an address or a name.</p>
<p><strong>src host</strong> host<br>
True if the IP source field of the packet is host.</p>
<p><strong>host</strong> host<br>
True if either the IP source or destination of the packet is host. Any of the above host expressions can be prepended with the<br>
keywords, ip, arp, or rarp as in:<br><strong>ip host </strong>host<br>
which is equivalent to:</p>
<p><strong>ether dst </strong>ehost<br>
True if the ethernet destination address is ehost. Ehost may be either a name from /etc/ethers or a number (see ethers(3N) for<br>
numeric format).</p>
<p><strong>ether src </strong>ehost<br>
True if the ethernet source address is ehost.</p>
<p><strong>ether host </strong>ehost<br>
True if either the ethernet source or destination address is ehost.</p>
<p><strong>gateway </strong>host<br>
True if the packet used host as a gateway. I.e., the ethernet source or destination address was host but neither the IP source<br>
nor the IP destination was host. Host must be a name and must be found in both /etc/hosts and /etc/ethers. (An equivalent<br>
expression is<br>
ether host ehost and not host host<br>
which can be used with either names or numbers for host / ehost.)</p>
<p><strong>dst net </strong>net<br>
True if the IP destination address of the packet has a network number of net. Net may be either a name from /etc/networks or a<br>
network number (see networks(4) for details).</p>
<p><strong>src net </strong>net<br>
True if the IP source address of the packet has a network number of net.</p>
<p><strong>net </strong>net<br>
True if either the IP source or destination address of the packet has a network number of net.</p>
<p><strong>net</strong> net <strong>mask</strong> mask<br>
True if the IP address matches net with the specific netmask. May be qualified with src or dst.</p>
<p><strong>net</strong> net/len<br>
True if the IP address matches net a netmask len bits wide. May be qualified with src or dst.</p>
<p><strong>dst port </strong>port<br>
True if the packet is ip/tcp or ip/udp and has a destination port value of port. The port can be a number or a name used in<br>
/etc/services (see tcp(4P) and udp(4P)). If a name is used, both the port number and protocol are checked. If a number or<br>
ambiguous name is used, only the port number is checked (e.g., dst port 513 will print both tcp/login traffic and udp/who traf-<br>
fic, and port domain will print both tcp/domain and udp/domain traffic).<br>
src port port<br>
True if the packet has a source port value of port.</p>
<p><strong>port</strong> port<br>
True if either the source or destination port of the packet is port. Any of the above port expressions can be prepended with<br>
the keywords, tcp or udp, as in:<br>
tcp src port port<br>
which matches only tcp packets whose source port is port.</p>
<p><strong>less </strong>length<br>
True if the packet has a length less than or equal to length. This is equivalent to:<br>
len <= length.</p>
<p><strong>greater </strong>length<br>
True if the packet has a length greater than or equal to length. This is equivalent to:<br>
len >= length.</p>
<p><strong>ip proto </strong>protocol<br>
True if the packet is an ip packet (see ip(4P)) of protocol type protocol. Protocol can be a number or one of the names tcp,<br>
udp or icmp. Note that the identifiers tcp and udp are also keywords and must be escaped via backslash (\), which is \\ in the<br>
C-shell.</p>
<p><strong>ip broadcast</strong><br>
True if the packet is an IP broadcast packet. It checks for both the all-zeroes and all-ones broadcast conventions, and looks<br>
up the local subnet mask.</p>
<p><strong>ip multicast</strong><br>
True if the packet is an IP multicast packet.</p>
<p><strong>ip </strong>Abbreviation for:<br><strong>ether proto ip</strong></p>
<p><strong>tcp, udp, icmp</strong><br>
Abbreviations for:<br><strong>ip proto</strong> p<br>
where p is one of the above protocols.</p>
<h3>实例</h3>
<p>抓本机eth0 与192.168.1.9的通信信息，并且以行来打印出来</p><pre class="brush:bash;toolbar:false">#ngrep -d eth0 -W byline host 192.168.1.9</pre><p>抓本机与192.168.1.8的通信端口为80（本机）的信息</p><pre class="brush:bash;toolbar:false"># ngrep -W byline host 192.168.1.8 and port 80</pre><p>抓本机与192.168.1.8和192.168.1.9的通信，并且本地端口为80</p><pre class="brush:bash;toolbar:false">#ngrep -W byline host 192.168.1.8 or host 192.168.1.9 port 80</pre><p>抓udp包</p><pre class="brush:bash;toolbar:false">#ngrep host 192.168.1.8 udp</pre><p><img src="https://zhuji.jb51.net/uploads/img/20230517/262ecf00fba38c58f83343c930d38849.jpg" width="813" height="472"></p>
<p>统计请求头长度</p><pre class="brush:bash;toolbar:false"># ngrep -W byline 'GET /' 'tcp and dst port 80' -d eth1 | awk -v RS="#+" -v FS="\n" '{ print length() }'</pre><p>查询一下大于 1K 的请求头</p><pre class="brush:bash;toolbar:false"># ngrep -W byline 'GET /' 'tcp and dst port 80' -d eth1 |awk -v RS="#+" -v FS="\n" 'length() > 1000'</pre><p></p>
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