Remove the openbsd netcat package
It will be replaced by ncat from the nmap project.
This commit is contained in:
Fredrik Fornwall
parent
dc90a1d50a
commit
9a50abbd96
@ -1,18 +0,0 @@
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TERMUX_PKG_HOMEPAGE=http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/nc.1
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TERMUX_PKG_DESCRIPTION="Utility for reading from and writing to connections using TCP or UDP"
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TERMUX_PKG_VERSION=1.103
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_COMMIT=b023a43765b15f0b0fd5b52b7d8021f515c59c23
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TERMUX_PKG_SRCURL=https://github.com/android/platform_external_netcat/archive/${_COMMIT}.zip
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TERMUX_PKG_FOLDERNAME=platform_external_netcat-$_COMMIT
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termux_step_make () {
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return
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}
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termux_step_make_install () {
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cd $TERMUX_PKG_SRCDIR
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CFLAGS+=" -DANDROID=1"
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$CC $CFLAGS $LDFLAGS *.c -o $TERMUX_PREFIX/bin/nc
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cp $TERMUX_PKG_BUILDER_DIR/nc.1 $TERMUX_PREFIX/share/man/man1/
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}
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@ -1,538 +0,0 @@
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.\" $OpenBSD: nc.1,v 1.60 2012/02/07 12:11:43 lum Exp $
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.\"
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.\" Copyright (c) 1996 David Sacerdote
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: February 7 2012 $
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.Dt NC 1
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.Os
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.Sh NAME
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.Nm nc
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.Nd arbitrary TCP and UDP connections and listens
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.Sh SYNOPSIS
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.Nm nc
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.Bk -words
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.Op Fl 46bCDdhklnrStUuvZz
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.Op Fl I Ar length
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.Op Fl i Ar interval
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.Op Fl O Ar length
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.Op Fl P Ar proxy_username
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.Op Fl p Ar source_port
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.Op Fl q Ar seconds
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.Op Fl s Ar source
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.Op Fl T Ar toskeyword
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.Op Fl V Ar rtable
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.Op Fl w Ar timeout
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.Op Fl X Ar proxy_protocol
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.Oo Xo
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.Fl x Ar proxy_address Ns Oo : Ns
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.Ar port Oc
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.Xc Oc
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.Op Ar destination
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.Op Ar port
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.Ek
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.Sh DESCRIPTION
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The
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.Nm
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(or
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.Nm netcat )
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utility is used for just about anything under the sun involving TCP,
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UDP, or
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.Ux Ns -domain
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sockets.
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It can open TCP connections, send UDP packets, listen on arbitrary
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TCP and UDP ports, do port scanning, and deal with both IPv4 and
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IPv6.
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Unlike
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.Xr telnet 1 ,
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.Nm
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scripts nicely, and separates error messages onto standard error instead
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of sending them to standard output, as
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.Xr telnet 1
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does with some.
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.Pp
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Common uses include:
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.Pp
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.Bl -bullet -offset indent -compact
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.It
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simple TCP proxies
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.It
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shell-script based HTTP clients and servers
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.It
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network daemon testing
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.It
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a SOCKS or HTTP ProxyCommand for
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.Xr ssh 1
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.It
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and much, much more
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.El
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl 4
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Forces
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.Nm
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to use IPv4 addresses only.
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.It Fl 6
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Forces
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.Nm
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to use IPv6 addresses only.
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.It Fl b
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Allow broadcast.
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.It Fl C
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Send CRLF as line-ending.
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.It Fl D
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Enable debugging on the socket.
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.It Fl d
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Do not attempt to read from stdin.
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.It Fl h
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Prints out
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.Nm
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help.
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.It Fl I Ar length
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Specifies the size of the TCP receive buffer.
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.It Fl i Ar interval
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Specifies a delay time interval between lines of text sent and received.
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Also causes a delay time between connections to multiple ports.
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.It Fl k
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Forces
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.Nm
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to stay listening for another connection after its current connection
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is completed.
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It is an error to use this option without the
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.Fl l
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option.
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.It Fl l
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Used to specify that
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.Nm
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should listen for an incoming connection rather than initiate a
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connection to a remote host.
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It is an error to use this option in conjunction with the
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.Fl p ,
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.Fl s ,
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or
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.Fl z
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options.
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Additionally, any timeouts specified with the
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.Fl w
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option are ignored.
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.It Fl n
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Do not do any DNS or service lookups on any specified addresses,
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hostnames or ports.
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.It Fl O Ar length
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Specifies the size of the TCP send buffer.
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.It Fl P Ar proxy_username
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Specifies a username to present to a proxy server that requires authentication.
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If no username is specified then authentication will not be attempted.
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Proxy authentication is only supported for HTTP CONNECT proxies at present.
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.It Fl p Ar source_port
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Specifies the source port
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.Nm
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should use, subject to privilege restrictions and availability.
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.It Fl q Ar seconds
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after EOF on stdin, wait the specified number of seconds and then quit. If
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.Ar seconds
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is negative, wait forever.
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.It Fl r
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Specifies that source and/or destination ports should be chosen randomly
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instead of sequentially within a range or in the order that the system
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assigns them.
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.It Fl S
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Enables the RFC 2385 TCP MD5 signature option.
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.It Fl s Ar source
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Specifies the IP of the interface which is used to send the packets.
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For
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.Ux Ns -domain
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datagram sockets, specifies the local temporary socket file
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to create and use so that datagrams can be received.
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It is an error to use this option in conjunction with the
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.Fl l
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option.
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.It Fl T Ar toskeyword
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Change IPv4 TOS value.
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.Ar toskeyword
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may be one of
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.Ar critical ,
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.Ar inetcontrol ,
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.Ar lowcost ,
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.Ar lowdelay ,
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.Ar netcontrol ,
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.Ar throughput ,
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.Ar reliability ,
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or one of the DiffServ Code Points:
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.Ar ef ,
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.Ar af11 ... af43 ,
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.Ar cs0 ... cs7 ;
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or a number in either hex or decimal.
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.It Fl t
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Causes
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.Nm
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to send RFC 854 DON'T and WON'T responses to RFC 854 DO and WILL requests.
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This makes it possible to use
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.Nm
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to script telnet sessions.
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.It Fl U
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Specifies to use
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.Ux Ns -domain
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sockets.
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.It Fl u
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Use UDP instead of the default option of TCP.
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For
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.Ux Ns -domain
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sockets, use a datagram socket instead of a stream socket.
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If a
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.Ux Ns -domain
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socket is used, a temporary receiving socket is created in
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.Pa /tmp
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unless the
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.Fl s
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flag is given.
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.It Fl V Ar rtable
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Set the routing table to be used.
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The default is 0.
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.It Fl v
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Have
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.Nm
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give more verbose output.
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.It Fl w Ar timeout
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Connections which cannot be established or are idle timeout after
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.Ar timeout
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seconds.
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The
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.Fl w
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flag has no effect on the
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.Fl l
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option, i.e.\&
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.Nm
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will listen forever for a connection, with or without the
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.Fl w
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flag.
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The default is no timeout.
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.It Fl X Ar proxy_protocol
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Requests that
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.Nm
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should use the specified protocol when talking to the proxy server.
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Supported protocols are
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.Dq 4
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(SOCKS v.4),
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.Dq 5
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(SOCKS v.5)
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and
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.Dq connect
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(HTTPS proxy).
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If the protocol is not specified, SOCKS version 5 is used.
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.It Xo
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.Fl x Ar proxy_address Ns Oo : Ns
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.Ar port Oc
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.Xc
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Requests that
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.Nm
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should connect to
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.Ar destination
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using a proxy at
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.Ar proxy_address
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and
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.Ar port .
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If
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.Ar port
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is not specified, the well-known port for the proxy protocol is used (1080
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for SOCKS, 3128 for HTTPS).
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.It Fl Z
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DCCP mode.
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.It Fl z
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Specifies that
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.Nm
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should just scan for listening daemons, without sending any data to them.
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It is an error to use this option in conjunction with the
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.Fl l
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option.
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.El
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.Pp
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.Ar destination
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can be a numerical IP address or a symbolic hostname
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(unless the
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.Fl n
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option is given).
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In general, a destination must be specified,
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unless the
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.Fl l
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option is given
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(in which case the local host is used).
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For
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.Ux Ns -domain
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sockets, a destination is required and is the socket path to connect to
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(or listen on if the
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.Fl l
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option is given).
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.Pp
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.Ar port
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can be a single integer or a range of ports.
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Ranges are in the form nn-mm.
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In general,
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a destination port must be specified,
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unless the
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.Fl U
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option is given.
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.Sh CLIENT/SERVER MODEL
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It is quite simple to build a very basic client/server model using
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.Nm .
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On one console, start
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.Nm
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listening on a specific port for a connection.
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For example:
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.Pp
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.Dl $ nc -l 1234
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.Pp
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.Nm
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is now listening on port 1234 for a connection.
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On a second console
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.Pq or a second machine ,
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connect to the machine and port being listened on:
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.Pp
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.Dl $ nc 127.0.0.1 1234
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.Pp
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There should now be a connection between the ports.
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Anything typed at the second console will be concatenated to the first,
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and vice-versa.
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After the connection has been set up,
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.Nm
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does not really care which side is being used as a
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.Sq server
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and which side is being used as a
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.Sq client .
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The connection may be terminated using an
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.Dv EOF
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.Pq Sq ^D .
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.Pp
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There is no
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.Fl c
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or
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.Fl e
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option in this netcat, but you still can execute a command after connection
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being established by redirecting file descriptors. Be cautious here because
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opening a port and let anyone connected execute arbitrary command on your
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site is DANGEROUS. If you really need to do this, here is an example:
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.Pp
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On
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.Sq server
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side:
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.Pp
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.Dl $ rm -f /tmp/f; mkfifo /tmp/f
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.Dl $ cat /tmp/f | /bin/sh -i 2>&1 | nc -l 127.0.0.1 1234 > /tmp/f
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.Pp
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On
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.Sq client
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side:
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.Pp
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.Dl $ nc host.example.com 1234
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.Dl $ (shell prompt from host.example.com)
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.Pp
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By doing this, you create a fifo at /tmp/f and make nc listen at port 1234
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of address 127.0.0.1 on
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.Sq server
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side, when a
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.Sq client
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establishes a connection successfully to that port, /bin/sh gets executed
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on
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.Sq server
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side and the shell prompt is given to
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.Sq client
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side.
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.Pp
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When connection is terminated,
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.Nm
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quits as well. Use
|
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.Fl k
|
||||
if you want it keep listening, but if the command quits this option won't
|
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restart it or keep
|
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.Nm
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||||
running. Also don't forget to remove the file descriptor once you don't need
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it anymore:
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.Pp
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.Dl $ rm -f /tmp/f
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.Pp
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.Sh DATA TRANSFER
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The example in the previous section can be expanded to build a
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basic data transfer model.
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Any information input into one end of the connection will be output
|
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to the other end, and input and output can be easily captured in order to
|
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emulate file transfer.
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.Pp
|
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Start by using
|
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.Nm
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to listen on a specific port, with output captured into a file:
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.Pp
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.Dl $ nc -l 1234 \*(Gt filename.out
|
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.Pp
|
||||
Using a second machine, connect to the listening
|
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.Nm
|
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process, feeding it the file which is to be transferred:
|
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.Pp
|
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.Dl $ nc host.example.com 1234 \*(Lt filename.in
|
||||
.Pp
|
||||
After the file has been transferred, the connection will close automatically.
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.Sh TALKING TO SERVERS
|
||||
It is sometimes useful to talk to servers
|
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.Dq by hand
|
||||
rather than through a user interface.
|
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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:
|
||||
.Bd -literal -offset indent
|
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$ printf "GET / HTTP/1.0\er\en\er\en" | nc host.example.com 80
|
||||
.Ed
|
||||
.Pp
|
||||
Note that this also displays the headers sent by the web server.
|
||||
They can be filtered, using a tool such as
|
||||
.Xr sed 1 ,
|
||||
if necessary.
|
||||
.Pp
|
||||
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:
|
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.Bd -literal -offset indent
|
||||
$ nc [\-C] localhost 25 \*(Lt\*(Lt EOF
|
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HELO host.example.com
|
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MAIL FROM:\*(Ltuser@host.example.com\*(Gt
|
||||
RCPT TO:\*(Ltuser2@host.example.com\*(Gt
|
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DATA
|
||||
Body of email.
|
||||
\&.
|
||||
QUIT
|
||||
EOF
|
||||
.Ed
|
||||
.Sh PORT SCANNING
|
||||
It may be useful to know which ports are open and running services on
|
||||
a target machine.
|
||||
The
|
||||
.Fl z
|
||||
flag can be used to tell
|
||||
.Nm
|
||||
to report open ports,
|
||||
rather than initiate a connection. Usually it's useful to turn on verbose
|
||||
output to stderr by use this option in conjunction with
|
||||
.Fl v
|
||||
option.
|
||||
.Pp
|
||||
For example:
|
||||
.Bd -literal -offset indent
|
||||
$ nc \-zv 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!
|
||||
.Ed
|
||||
.Pp
|
||||
The port range was specified to limit the search to ports 20 \- 30, and is
|
||||
scanned by increasing order.
|
||||
.Pp
|
||||
You can also specify a list of ports to scan, for example:
|
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.Bd -literal -offset indent
|
||||
$ nc \-zv host.example.com 80 20 22
|
||||
nc: connect to host.example.com 80 (tcp) failed: Connection refused
|
||||
nc: connect to host.example.com 20 (tcp) failed: Connection refused
|
||||
Connection to host.example.com port [tcp/ssh] succeeded!
|
||||
.Ed
|
||||
.Pp
|
||||
The ports are scanned by the order you given.
|
||||
.Pp
|
||||
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 necessary 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
|
||||
.Fl w
|
||||
flag, or perhaps by issuing a
|
||||
.Qq Dv QUIT
|
||||
command to the server:
|
||||
.Bd -literal -offset indent
|
||||
$ 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 Ready
|
||||
.Ed
|
||||
.Sh EXAMPLES
|
||||
Open a TCP connection to port 42 of host.example.com, using port 31337 as
|
||||
the source port, with a timeout of 5 seconds:
|
||||
.Pp
|
||||
.Dl $ nc -p 31337 -w 5 host.example.com 42
|
||||
.Pp
|
||||
Open a UDP connection to port 53 of host.example.com:
|
||||
.Pp
|
||||
.Dl $ nc -u host.example.com 53
|
||||
.Pp
|
||||
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:
|
||||
.Pp
|
||||
.Dl $ nc -s 10.1.2.3 host.example.com 42
|
||||
.Pp
|
||||
Create and listen on a
|
||||
.Ux Ns -domain
|
||||
stream socket:
|
||||
.Pp
|
||||
.Dl $ nc -lU /var/tmp/dsocket
|
||||
.Pp
|
||||
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
|
||||
.Xr ssh 1 ;
|
||||
see the
|
||||
.Cm ProxyCommand
|
||||
directive in
|
||||
.Xr ssh_config 5
|
||||
for more information.
|
||||
.Pp
|
||||
.Dl $ nc -x10.2.3.4:8080 -Xconnect host.example.com 42
|
||||
.Pp
|
||||
The same example again, this time enabling proxy authentication with username
|
||||
.Dq ruser
|
||||
if the proxy requires it:
|
||||
.Pp
|
||||
.Dl $ nc -x10.2.3.4:8080 -Xconnect -Pruser host.example.com 42
|
||||
.Sh SEE ALSO
|
||||
.Xr cat 1 ,
|
||||
.Xr ssh 1
|
||||
.Sh AUTHORS
|
||||
Original implementation by *Hobbit*
|
||||
.Aq hobbit@avian.org .
|
||||
.br
|
||||
Rewritten with IPv6 support by
|
||||
.An Eric Jackson Aq ericj@monkey.org .
|
||||
.br
|
||||
Modified for Debian port by Aron Xu
|
||||
.Aq aron@debian.org .
|
||||
.Sh CAVEATS
|
||||
UDP port scans using the
|
||||
.Fl uz
|
||||
combination of flags will always report success irrespective of
|
||||
the target machine's state.
|
||||
However,
|
||||
in conjunction with a traffic sniffer either on the target machine
|
||||
or an intermediary device,
|
||||
the
|
||||
.Fl uz
|
||||
combination could be useful for communications diagnostics.
|
||||
Note that the amount of UDP traffic generated may be limited either
|
||||
due to hardware resources and/or configuration settings.
|
||||
Loading…
Reference in New Issue
Block a user