Annotation of src/usr.bin/nc/nc.1, Revision 1.27
1.27 ! markus 1: .\" $OpenBSD: nc.1,v 1.26 2003/09/05 16:54:07 jmc Exp $
1.1 deraadt 2: .\"
3: .\" Copyright (c) 1996 David Sacerdote
4: .\" All rights reserved.
5: .\"
6: .\" Redistribution and use in source and binary forms, with or without
7: .\" modification, are permitted provided that the following conditions
8: .\" are met:
9: .\" 1. Redistributions of source code must retain the above copyright
10: .\" notice, this list of conditions and the following disclaimer.
11: .\" 2. Redistributions in binary form must reproduce the above copyright
12: .\" notice, this list of conditions and the following disclaimer in the
13: .\" documentation and/or other materials provided with the distribution.
14: .\" 3. The name of the author may not be used to endorse or promote products
15: .\" derived from this software without specific prior written permission
16: .\"
17: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27: .\"
1.13 ericj 28: .Dd June 25, 2001
1.3 aaron 29: .Dt NC 1
1.4 deraadt 30: .Os
1.1 deraadt 31: .Sh NAME
32: .Nm nc
1.5 millert 33: .Nd "arbitrary TCP and UDP connections and listens"
1.2 deraadt 34: .Sh SYNOPSIS
1.1 deraadt 35: .Nm nc
1.27 ! markus 36: .Op Fl 46hklnrtuvzSU
1.1 deraadt 37: .Op Fl i Ar interval
1.6 aaron 38: .Op Fl p Ar source port
1.13 ericj 39: .Op Fl s Ar source ip address
1.19 jakob 40: .Op Fl x Ar proxy address Op :port
1.6 aaron 41: .Op Fl w Ar timeout
1.22 markus 42: .Op Fl X Ar socks version
1.1 deraadt 43: .Op Ar hostname
1.13 ericj 44: .Op Ar port[s]
1.1 deraadt 45: .Sh DESCRIPTION
46: The
1.6 aaron 47: .Nm
1.1 deraadt 48: (or
49: .Nm netcat )
1.13 ericj 50: utility is used for just about anything under the sun involving TCP
51: or UDP.
52: It can open TCP connections, send UDP packets, listen on arbitrary
53: TCP and UDP ports, do port scanning, and deal with both IPv4 and
54: IPv6.
1.7 aaron 55: Unlike
1.1 deraadt 56: .Xr telnet 1 ,
1.6 aaron 57: .Nm
1.1 deraadt 58: scripts nicely, and separates error messages onto standard error instead
1.6 aaron 59: of sending them to standard output, as
1.24 pvalchev 60: .Xr telnet 1
1.6 aaron 61: does with some.
1.1 deraadt 62: .Pp
1.13 ericj 63: Destination ports can be single integers or ranges.
64: Ranges are in the form nn-mm.
1.1 deraadt 65: .Pp
66: Common uses include:
1.7 aaron 67: .Pp
68: .Bl -bullet -offset indent -compact
1.1 deraadt 69: .It
1.3 aaron 70: simple TCP proxies
1.1 deraadt 71: .It
1.3 aaron 72: shell\-script based HTTP clients and servers
1.1 deraadt 73: .It
1.13 ericj 74: network daemon testing
1.1 deraadt 75: .It
76: and much, much more
77: .El
78: .Pp
79: The options are as follows:
80: .Bl -tag -width Ds
1.13 ericj 81: .It Fl 4
82: Forces
83: .Nm
84: to use IPv4 addresses only.
85: .It Fl 6
86: Forces
87: .Nm
88: to use IPv6 addresses only.
89: .It Fl h
90: Prints out
91: .Nm
92: help.
93: .It Fl i Ar interval
1.1 deraadt 94: Specifies a delay time interval between lines of text sent and received.
95: Also causes a delay time between connections to multiple ports.
1.13 ericj 96: .It Fl k
97: Forces
98: .Nm
1.21 ericj 99: to stay listening for another connection after its current connection
1.13 ericj 100: is completed.
1.1 deraadt 101: .It Fl l
1.13 ericj 102: Used to specify that
1.6 aaron 103: .Nm
1.13 ericj 104: should listen for an incoming connection rather than initiate a
1.7 aaron 105: connection to a remote host.
1.1 deraadt 106: .It Fl n
1.21 ericj 107: Do not do any DNS or service lookups on any specified addresses,
108: hostnames or ports.
1.1 deraadt 109: .It Fl p Ar port
110: Specifies the source port
1.6 aaron 111: .Nm
1.1 deraadt 112: should use, subject to privilege restrictions and availability.
113: .It Fl r
1.13 ericj 114: Specifies that source and/or destination ports should be chosen randomly
115: instead of sequentially within a range or in the order that the system
1.21 ericj 116: assigns them.
1.13 ericj 117: .It Fl s Ar hostname/ip address
1.3 aaron 118: Specifies the IP of the interface which is used to send the packets.
1.1 deraadt 119: .It Fl t
120: Causes
1.6 aaron 121: .Nm
1.25 jmc 122: to send RFC 854 DON'T and WON'T responses to RFC 854 DO and WILL requests.
1.7 aaron 123: This makes it possible to use
1.6 aaron 124: .Nm
1.7 aaron 125: to script telnet sessions.
1.1 deraadt 126: .It Fl u
1.13 ericj 127: Use UDP instead of the default option of TCP.
1.1 deraadt 128: .It Fl v
1.13 ericj 129: Have
1.6 aaron 130: .Nm
1.13 ericj 131: give more verbose output.
1.26 jmc 132: .It Fl w Ar timeout
133: If a connection and stdin are idle for more than
134: .Ar timeout
135: seconds, then the connection is silently closed.
136: The
137: .Fl w
138: flag has no effect on the
139: .Fl l
140: option, i.e.\&
141: .Nm
142: will listen forever for a connection, with or without the
143: .Fl w
144: flag.
145: The default is no timeout.
1.19 jakob 146: .It Fl x Ar proxy address Op :port
147: Requests that
148: .Nm
149: should connect to
150: .Ar hostname
1.22 markus 151: using a SOCKS proxy at address and port.
1.19 jakob 152: If port is not specified, port 1080 is used.
1.1 deraadt 153: .It Fl z
154: Specifies that
1.6 aaron 155: .Nm
1.13 ericj 156: should just scan for listening daemons, without sending any data to them.
1.27 ! markus 157: .It Fl S
! 158: Enables the RFC 2385 TCP MD5 signature option.
1.20 ericj 159: .It Fl U
160: Specifies to use Unix Domain Sockets.
1.22 markus 161: .It Fl X Ar version
162: Requests that
163: .Nm
164: should use the specified version of the SOCKS protocol when talking to
165: a SOCKS proxy.
166: If version is not specified, SOCKS version 5 is used.
1.8 aaron 167: .El
1.1 deraadt 168: .Sh EXAMPLES
169: .Bl -tag -width x
1.23 deraadt 170: .It Li "$ nc hostname 42"
1.13 ericj 171: Open a TCP connection to port 42 of hostname.
1.23 deraadt 172: .It Li "$ nc -p 31337 hostname 42"
1.13 ericj 173: Open a TCP connection to port 42 of hostname, and use port 31337 as
174: the source port.
1.23 deraadt 175: .It Li "$ nc -w 5 hostname 42"
1.13 ericj 176: Open a TCP connection to port 42 of hostname, and timeout after
1.1 deraadt 177: five seconds while attempting to connect.
1.23 deraadt 178: .It Li "$ nc -u hostname 53"
1.13 ericj 179: Open a UDP connection to port 53 of hostname.
1.23 deraadt 180: .It Li "$ nc -s 10.1.2.3 example.host 42"
1.3 aaron 181: Open a TCP connection to port 42 of example.host using 10.1.2.3 as the
182: IP for the local end of the connection.
1.23 deraadt 183: .It Li "$ nc -v hostname 42"
1.13 ericj 184: Open a TCP connection to port 42 of hostname, displaying some
1.1 deraadt 185: diagnostic messages on stderr.
1.23 deraadt 186: .It Li "$ nc -v -z hostname 20-30"
1.3 aaron 187: Attempt to open TCP connections to ports 20 through 30 of
1.17 krw 188: hostname, and report which ones
1.6 aaron 189: .Nm
1.1 deraadt 190: was able to connect to.
1.23 deraadt 191: .It Li "$ nc -v -u -z -w 3 hostname 20-30"
1.3 aaron 192: Send UDP packets to ports 20-30 of example.host, and report which ones
1.1 deraadt 193: did not respond with an ICMP packet after three seconds.
1.23 deraadt 194: .It Li "$ nc -l 3000"
1.1 deraadt 195: Listen on TCP port 3000, and once there is a connection, send stdin to
196: the remote host, and send data from the remote host to stdout.
1.23 deraadt 197: .It Li "$ echo foobar | nc hostname 1000"
1.13 ericj 198: Connect to port 1000 of hostname, send the string "foobar"
199: followed by a newline, and move data from port 1000 of hostname to
200: stdout until hostname closes the connection.
1.23 deraadt 201: .It Li "$ nc -U /var/tmp/dsocket"
1.20 ericj 202: Connect to a Unix Domain Socket.
1.23 deraadt 203: .It Li "$ nc -lU /var/tmp/dsocket"
1.20 ericj 204: Create and listen on a Unix Domain Socket.
1.1 deraadt 205: .El
206: .Sh SEE ALSO
207: .Xr cat 1 ,
1.3 aaron 208: .Xr telnet 1
1.15 smart 209: .Sh AUTHORS
210: Original implementation by *Hobbit*
211: .Aq hobbit@avian.org .
212: .Pp
213: Rewritten with IPv6 support by Eric Jackson
214: .Aq ericj@monkey.org .
![[BACK]](/icons/back.gif){kind=icon}
Return to nc.1 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / nc