Annotation of src/usr.bin/nc/nc.1, Revision 1.20
1.20 ! ericj 1: .\" $OpenBSD: nc.1,v 1.19 2001/09/02 18:45:41 jakob 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
1.20 ! 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
1.1 deraadt 42: .Op Ar hostname
1.13 ericj 43: .Op Ar port[s]
1.1 deraadt 44: .Sh DESCRIPTION
45: The
1.6 aaron 46: .Nm
1.1 deraadt 47: (or
48: .Nm netcat )
1.13 ericj 49: utility is used for just about anything under the sun involving TCP
50: or UDP.
51: It can open TCP connections, send UDP packets, listen on arbitrary
52: TCP and UDP ports, do port scanning, and deal with both IPv4 and
53: IPv6.
1.7 aaron 54: Unlike
1.1 deraadt 55: .Xr telnet 1 ,
1.6 aaron 56: .Nm
1.1 deraadt 57: scripts nicely, and separates error messages onto standard error instead
1.6 aaron 58: of sending them to standard output, as
1.13 ericj 59: .Xr telnet 1 ,
1.6 aaron 60: does with some.
1.1 deraadt 61: .Pp
1.13 ericj 62: Destination ports can be single integers or ranges.
63: Ranges are in the form nn-mm.
1.1 deraadt 64: .Pp
65: Common uses include:
1.7 aaron 66: .Pp
67: .Bl -bullet -offset indent -compact
1.1 deraadt 68: .It
1.3 aaron 69: simple TCP proxies
1.1 deraadt 70: .It
1.3 aaron 71: shell\-script based HTTP clients and servers
1.1 deraadt 72: .It
1.13 ericj 73: network daemon testing
1.1 deraadt 74: .It
75: and much, much more
76: .El
77: .Pp
78: The options are as follows:
79: .Bl -tag -width Ds
1.13 ericj 80: .It Fl 4
81: Forces
82: .Nm
83: to use IPv4 addresses only.
84: .It Fl 6
85: Forces
86: .Nm
87: to use IPv6 addresses only.
88: .It Fl h
89: Prints out
90: .Nm
91: help.
92: .It Fl i Ar interval
1.1 deraadt 93: Specifies a delay time interval between lines of text sent and received.
94: Also causes a delay time between connections to multiple ports.
1.13 ericj 95: .It Fl k
96: Forces
97: .Nm
1.14 jasoni 98: to stay listening for another connection after it's current connection
1.13 ericj 99: is completed.
1.1 deraadt 100: .It Fl l
1.13 ericj 101: Used to specify that
1.6 aaron 102: .Nm
1.13 ericj 103: should listen for an incoming connection rather than initiate a
1.7 aaron 104: connection to a remote host.
1.1 deraadt 105: .It Fl n
1.13 ericj 106: Do not do any DNS or service lookups on any specified addresses or
107: hostnames, or ports.
1.1 deraadt 108: .It Fl p Ar port
109: Specifies the source port
1.6 aaron 110: .Nm
1.1 deraadt 111: should use, subject to privilege restrictions and availability.
112: .It Fl r
1.13 ericj 113: Specifies that source and/or destination ports should be chosen randomly
114: instead of sequentially within a range or in the order that the system
115: assigns.
116: .It Fl s Ar hostname/ip address
1.3 aaron 117: Specifies the IP of the interface which is used to send the packets.
1.1 deraadt 118: .It Fl t
119: Causes
1.6 aaron 120: .Nm
1.13 ericj 121: to send RFC854 DON'T and WON'T responses to RFC854 DO and WILL requests.
1.7 aaron 122: This makes it possible to use
1.6 aaron 123: .Nm
1.7 aaron 124: to script telnet sessions.
1.1 deraadt 125: .It Fl u
1.13 ericj 126: Use UDP instead of the default option of TCP.
1.1 deraadt 127: .It Fl v
1.13 ericj 128: Have
1.6 aaron 129: .Nm
1.13 ericj 130: give more verbose output.
1.19 jakob 131: .It Fl x Ar proxy address Op :port
132: Requests that
133: .Nm
134: should connect to
135: .Ar hostname
136: using a socks5 proxy at address and port.
137: If port is not specified, port 1080 is used.
1.1 deraadt 138: .It Fl z
139: Specifies that
1.6 aaron 140: .Nm
1.13 ericj 141: should just scan for listening daemons, without sending any data to them.
1.20 ! ericj 142: .It Fl U
! 143: Specifies to use Unix Domain Sockets.
1.8 aaron 144: .El
1.1 deraadt 145: .Sh EXAMPLES
146: .Bl -tag -width x
1.13 ericj 147: .It Li "nc hostname 42"
148: Open a TCP connection to port 42 of hostname.
149: .It Li "nc -p 31337 hostname 42"
150: Open a TCP connection to port 42 of hostname, and use port 31337 as
151: the source port.
152: .It Li "nc -w 5 hostname 42"
153: Open a TCP connection to port 42 of hostname, and timeout after
1.1 deraadt 154: five seconds while attempting to connect.
1.13 ericj 155: .It Li "nc -u hostname 53"
156: Open a UDP connection to port 53 of hostname.
1.1 deraadt 157: .It Li "nc -s 10.1.2.3 example.host 42"
1.3 aaron 158: Open a TCP connection to port 42 of example.host using 10.1.2.3 as the
159: IP for the local end of the connection.
1.13 ericj 160: .It Li "nc -v hostname 42"
161: Open a TCP connection to port 42 of hostname, displaying some
1.1 deraadt 162: diagnostic messages on stderr.
1.13 ericj 163: .It Li "nc -v -v hostname 42"
164: Open a TCP connection to port 42 of hostname, displaying all
1.1 deraadt 165: diagnostic messages on stderr.
1.13 ericj 166: .It Li "nc -v -z hostname 20-30"
1.3 aaron 167: Attempt to open TCP connections to ports 20 through 30 of
1.17 krw 168: hostname, and report which ones
1.6 aaron 169: .Nm
1.1 deraadt 170: was able to connect to.
1.13 ericj 171: .It Li "nc -v -u -z -w 3 hostname 20-30"
1.3 aaron 172: Send UDP packets to ports 20-30 of example.host, and report which ones
1.1 deraadt 173: did not respond with an ICMP packet after three seconds.
1.16 ericj 174: .It Li "nc -l 3000"
1.1 deraadt 175: Listen on TCP port 3000, and once there is a connection, send stdin to
176: the remote host, and send data from the remote host to stdout.
1.13 ericj 177: .It Li "echo foobar | nc hostname 1000"
178: Connect to port 1000 of hostname, send the string "foobar"
179: followed by a newline, and move data from port 1000 of hostname to
180: stdout until hostname closes the connection.
1.20 ! ericj 181: .It Li "nc -U /var/tmp/dsocket"
! 182: Connect to a Unix Domain Socket.
! 183: .It Li "nc -lU /var/tmp/dsocket"
! 184: Create and listen on a Unix Domain Socket.
1.1 deraadt 185: .El
186: .Sh SEE ALSO
187: .Xr cat 1 ,
1.3 aaron 188: .Xr telnet 1
1.15 smart 189: .Sh AUTHORS
190: Original implementation by *Hobbit*
191: .Aq hobbit@avian.org .
192: .Pp
193: Rewritten with IPv6 support by Eric Jackson
194: .Aq ericj@monkey.org .
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