Annotation of src/usr.bin/nc/nc.1, Revision 1.22
1.22 ! markus 1: .\" $OpenBSD: nc.1,v 1.21 2002/02/19 22:45:18 ericj Exp $
1.1 deraadt 2: .\"
3: .\" Copyright (c) 1996 David Sacerdote
4: .\" All rights reserved.
5: .\"
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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
1.20 ericj 36: .Op Fl 46hklnrtuvzU
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
1.13 ericj 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
1.13 ericj 122: to send RFC854 DON'T and WON'T responses to RFC854 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.
1.19 jakob 132: .It Fl x Ar proxy address Op :port
133: Requests that
134: .Nm
135: should connect to
136: .Ar hostname
1.22 ! markus 137: using a SOCKS proxy at address and port.
1.19 jakob 138: If port is not specified, port 1080 is used.
1.1 deraadt 139: .It Fl z
140: Specifies that
1.6 aaron 141: .Nm
1.13 ericj 142: should just scan for listening daemons, without sending any data to them.
1.20 ericj 143: .It Fl U
144: Specifies to use Unix Domain Sockets.
1.22 ! markus 145: .It Fl X Ar version
! 146: Requests that
! 147: .Nm
! 148: should use the specified version of the SOCKS protocol when talking to
! 149: a SOCKS proxy.
! 150: If version is not specified, SOCKS version 5 is used.
1.8 aaron 151: .El
1.1 deraadt 152: .Sh EXAMPLES
153: .Bl -tag -width x
1.13 ericj 154: .It Li "nc hostname 42"
155: Open a TCP connection to port 42 of hostname.
156: .It Li "nc -p 31337 hostname 42"
157: Open a TCP connection to port 42 of hostname, and use port 31337 as
158: the source port.
159: .It Li "nc -w 5 hostname 42"
160: Open a TCP connection to port 42 of hostname, and timeout after
1.1 deraadt 161: five seconds while attempting to connect.
1.13 ericj 162: .It Li "nc -u hostname 53"
163: Open a UDP connection to port 53 of hostname.
1.1 deraadt 164: .It Li "nc -s 10.1.2.3 example.host 42"
1.3 aaron 165: Open a TCP connection to port 42 of example.host using 10.1.2.3 as the
166: IP for the local end of the connection.
1.13 ericj 167: .It Li "nc -v hostname 42"
168: Open a TCP connection to port 42 of hostname, displaying some
1.1 deraadt 169: diagnostic messages on stderr.
1.13 ericj 170: .It Li "nc -v -z hostname 20-30"
1.3 aaron 171: Attempt to open TCP connections to ports 20 through 30 of
1.17 krw 172: hostname, and report which ones
1.6 aaron 173: .Nm
1.1 deraadt 174: was able to connect to.
1.13 ericj 175: .It Li "nc -v -u -z -w 3 hostname 20-30"
1.3 aaron 176: Send UDP packets to ports 20-30 of example.host, and report which ones
1.1 deraadt 177: did not respond with an ICMP packet after three seconds.
1.16 ericj 178: .It Li "nc -l 3000"
1.1 deraadt 179: Listen on TCP port 3000, and once there is a connection, send stdin to
180: the remote host, and send data from the remote host to stdout.
1.13 ericj 181: .It Li "echo foobar | nc hostname 1000"
182: Connect to port 1000 of hostname, send the string "foobar"
183: followed by a newline, and move data from port 1000 of hostname to
184: stdout until hostname closes the connection.
1.20 ericj 185: .It Li "nc -U /var/tmp/dsocket"
186: Connect to a Unix Domain Socket.
187: .It Li "nc -lU /var/tmp/dsocket"
188: Create and listen on a Unix Domain Socket.
1.1 deraadt 189: .El
190: .Sh SEE ALSO
191: .Xr cat 1 ,
1.3 aaron 192: .Xr telnet 1
1.15 smart 193: .Sh AUTHORS
194: Original implementation by *Hobbit*
195: .Aq hobbit@avian.org .
196: .Pp
197: Rewritten with IPv6 support by Eric Jackson
198: .Aq ericj@monkey.org .
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