前言

nc (NetCat) 是一个使用 TCP/IP 来读写网络数据的小工具。

Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP protocol.

It is designed to be a reliable “back-end” tool that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities.

It provides access to the following main features:

• Outbound and inbound connections, TCP or UDP, to or from any ports.
• Featured tunneling mode which allows also special tunneling such as UDP to TCP, with the possibility of specifying all network parameters (source port/interface, listening port/interface, and the remote host allowed to connect to the tunnel.
• Built-in port-scanning capabilities, with randomizer.
• Advanced usage options, such as buffered send-mode (one line every N seconds), and hexdump (to stderr or to a specified file) of trasmitted and received data.
• Optional RFC854 telnet codes parser and responder.

The GNU Netcat is distributed freely under the GNU General Public License (GPL).

下面分享一下它的基本用法

参数文档

Tip: 目前官方版本还是 11 Jan 2004 年 发布的 Netcat 0.7.1 ，访问官网可能得翻墙

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概要

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安装nc

[[email protected] ~]# yum -y install nc 
Loaded plugins: dellsysid, fastestmirror, refresh-packagekit, security
Setting up Install Process
Loading mirror speeds from cached hostfile
epel/metalink                                                                                                | 5.5 kB     00:00     
 * base: mirrors.163.com
 * epel: ftp.riken.jp
 * extras: mirrors.aliyun.com
 * updates: mirrors.163.com
base                                                                                                         | 3.7 kB     00:00     
dell-omsa-indep                                                                                              | 1.9 kB     00:00     
dell-omsa-specific                                                                                           | 1.9 kB     00:00     
elasticsearch-1.5                                                                                            | 2.9 kB     00:01     
epel                                                                                                         | 4.3 kB     00:00     
epel/primary_db                                                                                              | 5.7 MB     02:11     
extras                                                                                                       | 3.4 kB     00:00     
http://yum.theforeman.org/releases/1.8/el6/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://yum.theforeman.org/releases/1.8/el6/x86_64/repodata/repomd.xml: (28, 'Operation too slow. Less than 1 bytes/sec transfered the last 30 seconds')
Trying other mirror.
foreman-plugins                                                                                              | 2.9 kB     00:02     
mongodb-org-3.0                                                                                              | 2.9 kB     00:00     
percona-release-noarch                                                                                       |  951 B     00:00     
percona-release-x86_64                                                                                       |  951 B     00:00     
puppetlabs-deps                                                                                              | 2.5 kB     00:00     
puppetlabs-products                                                                                          | 2.5 kB     00:00     
rabbitmq_rabbitmq-server/signature                                                                           |  836 B     00:00     
rabbitmq_rabbitmq-server/signature                                                                           | 1.0 kB     00:00 ... 
rabbitmq_rabbitmq-server-source/signature                                                                    |  836 B     00:00     
rabbitmq_rabbitmq-server-source/signature                                                                    | 1.0 kB     00:00 ... 
rhscl-ruby193-epel-6-x86_64                                                                                  | 3.0 kB     00:00     
rhscl-v8314-epel-6-x86_64                                                                                    | 3.0 kB     00:00     
updates                                                                                                      | 3.4 kB     00:00     
varnish-4.0                                                                                                  |  951 B     00:00     
zabbix                                                                                                       |  951 B     00:00     
zabbix-non-supported                                                                                         |  951 B     00:00     
Resolving Dependencies
--> Running transaction check
---> Package nc.x86_64 0:1.84-24.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================================================
 Package                    Arch                           Version                               Repository                    Size
====================================================================================================================================
Installing:
 nc                         x86_64                         1.84-24.el6                           base                          57 k

Transaction Summary
====================================================================================================================================
Install       1 Package(s)

Total download size: 57 k
Installed size: 109 k
Downloading Packages:
nc-1.84-24.el6.x86_64.rpm                                                                                    |  57 kB     00:00     
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
** Found 6 pre-existing rpmdb problem(s), 'yum check' output follows:
perl-DBD-MySQL-4.013-3.el6.x86_64 has missing requires of libmysqlclient.so.16()(64bit)
perl-DBD-MySQL-4.013-3.el6.x86_64 has missing requires of libmysqlclient.so.16(libmysqlclient_16)(64bit)
ruby-mysql-2.8.2-1.el6.x86_64 has missing requires of libmysqlclient.so.16()(64bit)
ruby-mysql-2.8.2-1.el6.x86_64 has missing requires of libmysqlclient.so.16(libmysqlclient_16)(64bit)
ruby193-rubygem-mysql2-0.3.11-4.el6.x86_64 has missing requires of libmysqlclient_r.so.16()(64bit)
ruby193-rubygem-mysql2-0.3.11-4.el6.x86_64 has missing requires of libmysqlclient_r.so.16(libmysqlclient_16)(64bit)
  Installing : nc-1.84-24.el6.x86_64                                                                                            1/1 
  Verifying  : nc-1.84-24.el6.x86_64                                                                                            1/1 

Installed:
  nc.x86_64 0:1.84-24.el6                                                                                                           

Complete!
[[email protected] ~]#