标签：des style c class blog code
即NetCat简写，在网络工具中有“瑞士军刀”美誉，其有Windows和Linux的版本。因为它短小精悍（1.84版本也不过25k，旧版本或缩减版甚至更小）、功能实用，被设计为一个简单、可靠的网络工具，可通过TCP或UDP协议传输读写数据。同时，它还是一个网络应用Debug分析器，因为它可以根据需要创建各种不同类型的网络连接。NetCat 官方地址：http://netcat.sourceforge.net/
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功能说明：功能强大的网络工具语 法：nc [-hlnruz][-g<网关...>][-G<指向器数目>][-i<延迟秒数>][-o<输出文件>][-p<通信端口>][-s<来源位址>][-v...][-w<超时秒数>][主机名称][通信端口...]参 数： -g <网关> 设置路由器跃程通信网关，最多可设置8个。 -G <指向器数目> 设置来源路由指向器，其数值为4的倍数。 -h 在线帮助。 -i <延迟秒数> 设置时间间隔，以便传送信息及扫描通信端口。 -l 使用监听模式，管控传入的资料。 -n 直接使用IP地址，而不通过域名服务器。 -o <输出文件> 指定文件名称，把往来传输的数据以16进制字码倾倒成该文件保存。 -p <通信端口> 设置本地主机使用的通信端口。 -r 乱数指定本地与远端主机的通信端口。 -s <来源位址> 设置本地主机送出数据包的IP地址。 -u 使用UDP传输协议。 -v 显示指令执行过程。 -w <超时秒数> 设置等待连线的时间。 -z 使用0输入/输出模式，只在扫描通信端口时使用。 |
1.端口扫描
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[root@rusky2 ~]# nc -v 192.168.2.100 -z 11162-11170Connection to 192.168.2.100 11162 port [tcp/suncacao-jmxmp] succeeded!Connection to 192.168.2.100 11163 port [tcp/suncacao-rmi] succeeded!Connection to 192.168.2.100 11164 port [tcp/suncacao-csa] succeeded!nc: connect to 192.168.2.100 port 11165 (tcp) failed: Connection refusednc: connect to 192.168.2.100 port 11166 (tcp) failed: Connection refusednc: connect to 192.168.2.100 port 11167 (tcp) failed: Connection refusednc: connect to 192.168.2.100 port 11168 (tcp) failed: Connection refusednc: connect to 192.168.2.100 port 11169 (tcp) failed: Connection refusednc: connect to 192.168.2.100 port 11170 (tcp) failed: Connection refused |
不加-v参数，则只显示已打开的端口
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[root@rusky2 ~]# nc 192.168.2.100 -z 11162-11170Connection to 192.168.2.100 11162 port [tcp/suncacao-jmxmp] succeeded!Connection to 192.168.2.100 11163 port [tcp/suncacao-rmi] succeeded!Connection to 192.168.2.100 11164 port [tcp/suncacao-csa] succeeded! |
2、简单聊天工具
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[root@rusky ~]# nc -l 1234 #rusky开始端口1234hello ruskyhello rusky2[root@rusky2 ~]# nc 192.168.2.100 1234 #rusk2连接端口1234hello ruskyhello rusky2 |
[root@rusky ~]# netstat -an | grep 1234
tcp
0 0 0.0.0.0:1234 0.0.0.0:* LISTEN
tcp 0 0 192.168.2.100:1234
192.168.2.200:58039 ESTABLISHED
3.。。。。。。。。
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[root@YncmIAM-ESP-a ~]# man 1 ncNC(1) BSD General Commands Manual NC(1)NAME nc - arbitrary TCP and UDP connections and listensSYNOPSIS nc [-46DdhklnrStUuvz] [-i interval] [-p source_port] [-s source_ip_address] [-T ToS] [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]] [hostname] [port[s]]DESCRIPTION The nc (or netcat) utility is
used for
just about anything under the sun involving TCP or UDP. It can open TCP connections, send UDP packets, listen on
arbitrary TCP and UDP ports, do
port scanning, and deal with both IPv4 and IPv6. Unlike telnet(1), nc scripts nicely, and separates error messages onto standard error instead of sending them to standard output, as
telnet(1) does with some. Common uses include: ??¤ simple TCP proxies ??¤ shell-script based HTTP clients and servers ??¤ network daemon testing ??¤ a SOCKS or HTTP ProxyCommand for
ssh(1) ??¤ and much, much more The options are as
follows: -4 Forces nc to use IPv4 addresses only. -6 Forces nc to use IPv6 addresses only. -D Enable debugging on
the socket. -d Do not attempt to read from
stdin. -h Prints out
nc help. -i interval Specifies a delay time interval between lines of text sent and received. Also causes a delay time between connections to multiple ports. -k Forces nc to stay listening for
another connection after its current connection is
completed. It is
an error to use this
option without the -l option. -l Used to specify that nc should listen for
an incoming connection rather than initiate a con- nection to a remote host. It is
an error to use this
option in
conjunction with the -p, -s, or -z options. Additionally, any timeouts specified with the -w option are ignored. -n Do not do
any DNS or service lookups on
any specified addresses, hostnames or ports. -p source_port Specifies the source port nc should use, subject to privilege restrictions and availability. It is
an error to use this
option in
conjunction with the -l option. -r Specifies that source and/or destination ports should be chosen randomly instead of sequen- tially within a range or in
the order that the system assigns them. -S Enables the RFC 2385 TCP MD5 signature option. -s source_ip_address Specifies the IP of the interface
which is
used to send the packets. It is
an error to use this
option in
conjunction with the -l option. -T ToS Specifies IP Type of Service (ToS) for
the connection. Valid values are the tokens ?°lowdelay?±, ?°throughput?±, ?°reliability?±, or an 8-bit hexadecimal value preceded by
?°0x?±. -t Causes nc to send RFC 854 DON?ˉT and WON?ˉT responses to RFC 854 DO and WILL requests. This makes it possible to use nc to script telnet sessions. -U Specifies to use Unix Domain Sockets. -u Use UDP instead of the default
option of TCP. -v Have nc give more verbose output. -w timeout If a connection and stdin are idle for
more than timeout seconds, then the connection is silently closed. The -w flag has no effect on
the -l option, i.e. nc will listen forever for a connection, with or without the -w flag. The default
is no timeout. -X proxy_version Requests that nc should use the specified protocol when talking to the proxy server. Sup- ported protocols are ?°4?± (SOCKS v.4), ?°5?± (SOCKS v.5) and ?°connect?± (HTTPS proxy). If the protocol is
not specified, SOCKS version 5 is
used. -x proxy_address[:port] Requests that nc should connect to hostname using
a proxy at proxy_address and port. If port is
not specified, the well-known port for
the proxy protocol is
used (1080 for
SOCKS, 3128 for HTTPS). -z Specifies that nc should just scan for
listening daemons, without sending any data to them. It is
an error to use this
option in
conjunction with the -l option. hostname can be a numerical IP address or a symbolic hostname (unless the -n option is
given). In general, a hostname must be specified, unless the -l option is
given (in
which case
the local host is used). port[s] can be single integers or ranges. Ranges are in
the form nn-mm. In general, a destination port must be specified, unless the -U option is
given (in
which case
a socket must be specified).CLIENT/SERVER MODEL It is
quite simple to build a very basic client/server model using
nc. On one console, start nc lis- tening on
a specific port for
a connection. For example: $ nc -l 1234 nc is
now listening on
port 1234 for
a connection. On a second console (or a second machine), connect to the machine and port being listened on: $ nc 127.0.0.1 1234 There should now be a connection between the ports. Anything typed at the second console will be con- catenated to the first, and vice-versa. After the connection has been set
up, nc does not really care which side is
being used as
a ??server?ˉ and which side is
being used as
a ??client?ˉ. The connection may be terminated using
an EOF (??^D?ˉ).DATA TRANSFER The example in
the previous section can be expanded to build a basic data transfer model. Any infor- mation input into
one end of the connection will be output to the other end, and input and output can be easily captured in
order to emulate file transfer. Start by
using nc to listen on
a specific port, with output captured into
a file: $ nc -l 1234 > filename.out Using a second machine, connect to the listening nc process, feeding it the file which is
to be trans- ferred: $ nc host.example.com 1234 < filename.in After the file has been transferred, the connection will close automatically.TALKING TO SERVERS It is
sometimes useful to talk to servers ?°by
hand?± rather than through a user interface. It can aid in
troubleshooting, when it might be necessary to verify what data a server is
sending in
response to commands issued by
the client. For example, to retrieve the home page of a web site: $ echo -n "GET / HTTP/1.0\r\n\r\n"
| nc host.example.com 80 Note that this
also displays the headers sent by
the web server. They can be filtered, using
a tool such as
sed(1), if
necessary. More complicated examples can be built up when the user knows the format of requests required by
the server. As another example, an email may be submitted to an SMTP server using: $ nc localhost 25 << EOF HELO host.example.com MAIL FROM: <user@host.example.com> RCPT TO: <user2@host.example.com> DATA Body of email. . QUIT EOFPORT SCANNING It may be useful to know which ports are open and running services on
a target machine. The -z flag can be used to tell nc to report open ports, rather than initiate a connection. For example: $ nc -z host.example.com 20-30 Connection to host.example.com 22 port [tcp/ssh] succeeded! Connection to host.example.com 25 port [tcp/smtp] succeeded! The port range was specified to limit the search to ports 20 - 30. Alternatively, it might be useful to know which server software is
running, and which versions. This information is
often contained within the greeting banners. In order to retrieve these, it is
neces- sary to first make a connection, and then break
the connection when the banner has been retrieved. This can be accomplished by
specifying a small timeout with the -w flag, or perhaps by
issuing a "QUIT"
command to the server: $ echo "QUIT"
| nc host.example.com 20-30 SSH-1.99-OpenSSH_3.6.1p2 Protocol mismatch. 220 host.example.com IMS SMTP Receiver Version 0.84 ReadyEXAMPLES Open a TCP connection to port 42 of host.example.com, using
port 31337 as
the source port, with a timeout of 5 seconds: <strong> $ nc -p 31337 -w 5 host.example.com 42</strong> Open a UDP connection to port 53 of host.example.com: <strong> $ nc -u host.example.com 53</strong> Open a TCP connection to port 42 of host.example.com using
10.1.2.3 as
the IP for
the local end of the connection: $ nc -s 10.1.2.3 host.example.com 42 Create and listen on
a Unix Domain Socket: $ nc -lU /var/tmp/dsocket Connect to port 42 of host.example.com via an HTTP proxy at 10.2.3.4, port 8080. This example could also be used by
ssh(1); see the ProxyCommand directive in
ssh_config(5) for
more information. $ nc -x10.2.3.4:8080 -Xconnect host.example.com 42SEE ALSO cat(1), ssh(1)AUTHORS Original implementation by
*Hobbit* ?′hobbit@avian.org?μ. Rewritten with IPv6 support by
Eric Jackson ?′ericj@monkey.org?μ.CAVEATS UDP port scans will always succeed (i.e. report the port as
open), rendering the -uz combination of flags relatively useless.BSD |
标签：des style c class blog code
原文地址：http://www.cnblogs.com/rusking/p/3746810.html
