Annotation of src/usr.bin/nc/nc.1, Revision 1.15
1.15 ! smart 1: .\" $OpenBSD: nc.1,v 1.14 2001/06/26 14:14:14 jasoni Exp $
1.1 deraadt 2: .\"
3: .\" Copyright (c) 1996 David Sacerdote
4: .\" All rights reserved.
5: .\"
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7: .\" modification, are permitted provided that the following conditions
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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
1.13 ericj 36: .Op Fl 46hklnrtuvz
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
1.6 aaron 40: .Op Fl w Ar timeout
1.1 deraadt 41: .Op Ar hostname
1.13 ericj 42: .Op Ar port[s]
1.1 deraadt 43: .Sh DESCRIPTION
44: The
1.6 aaron 45: .Nm
1.1 deraadt 46: (or
47: .Nm netcat )
1.13 ericj 48: utility is used for just about anything under the sun involving TCP
49: or UDP.
50: It can open TCP connections, send UDP packets, listen on arbitrary
51: TCP and UDP ports, do port scanning, and deal with both IPv4 and
52: IPv6.
1.7 aaron 53: Unlike
1.1 deraadt 54: .Xr telnet 1 ,
1.6 aaron 55: .Nm
1.1 deraadt 56: scripts nicely, and separates error messages onto standard error instead
1.6 aaron 57: of sending them to standard output, as
1.13 ericj 58: .Xr telnet 1 ,
1.6 aaron 59: does with some.
1.1 deraadt 60: .Pp
1.13 ericj 61: Destination ports can be single integers or ranges.
62: Ranges are in the form nn-mm.
1.1 deraadt 63: .Pp
64: Common uses include:
1.7 aaron 65: .Pp
66: .Bl -bullet -offset indent -compact
1.1 deraadt 67: .It
1.3 aaron 68: simple TCP proxies
1.1 deraadt 69: .It
1.3 aaron 70: shell\-script based HTTP clients and servers
1.1 deraadt 71: .It
72: network daemon testing
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
1.14 jasoni 99: to stay listening for another connection after it's 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
1.13 ericj 107: Do not do any DNS or service lookups on any specified addresses or
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
116: assigns.
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.
1.1 deraadt 132: .It Fl z
133: Specifies that
1.6 aaron 134: .Nm
1.13 ericj 135: should just scan for listening daemons, without sending any data to them.
1.8 aaron 136: .El
1.1 deraadt 137: .Sh EXAMPLES
138: .Bl -tag -width x
1.13 ericj 139: .It Li "nc hostname 42"
140: Open a TCP connection to port 42 of hostname.
141: .It Li "nc -p 31337 hostname 42"
142: Open a TCP connection to port 42 of hostname, and use port 31337 as
143: the source port.
144: .It Li "nc -w 5 hostname 42"
145: Open a TCP connection to port 42 of hostname, and timeout after
1.1 deraadt 146: five seconds while attempting to connect.
1.13 ericj 147: .It Li "nc -u hostname 53"
148: Open a UDP connection to port 53 of hostname.
1.1 deraadt 149: .It Li "nc -s 10.1.2.3 example.host 42"
1.3 aaron 150: Open a TCP connection to port 42 of example.host using 10.1.2.3 as the
151: IP for the local end of the connection.
1.13 ericj 152: .It Li "nc -v hostname 42"
153: Open a TCP connection to port 42 of hostname, displaying some
1.1 deraadt 154: diagnostic messages on stderr.
1.13 ericj 155: .It Li "nc -v -v hostname 42"
156: Open a TCP connection to port 42 of hostname, displaying all
1.1 deraadt 157: diagnostic messages on stderr.
1.13 ericj 158: .It Li "nc -v -z hostname 20-30"
1.3 aaron 159: Attempt to open TCP connections to ports 20 through 30 of
1.13 ericj 160: hostname , and report which ones
1.6 aaron 161: .Nm
1.1 deraadt 162: was able to connect to.
1.13 ericj 163: .It Li "nc -v -u -z -w 3 hostname 20-30"
1.3 aaron 164: Send UDP packets to ports 20-30 of example.host, and report which ones
1.1 deraadt 165: did not respond with an ICMP packet after three seconds.
166: .It Li "nc -l -p 3000"
167: Listen on TCP port 3000, and once there is a connection, send stdin to
168: the remote host, and send data from the remote host to stdout.
1.13 ericj 169: .It Li "echo foobar | nc hostname 1000"
170: Connect to port 1000 of hostname, send the string "foobar"
171: followed by a newline, and move data from port 1000 of hostname to
172: stdout until hostname closes the connection.
1.1 deraadt 173: .El
174: .Sh SEE ALSO
175: .Xr cat 1 ,
1.3 aaron 176: .Xr telnet 1
1.15 ! smart 177: .Sh AUTHORS
! 178: Original implementation by *Hobbit*
! 179: .Aq hobbit@avian.org .
! 180: .Pp
! 181: Rewritten with IPv6 support by Eric Jackson
! 182: .Aq ericj@monkey.org .
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