README

Netcat 2.0
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                                                                  / 0 0 \
Netcat is a simple Unix utility which reads and writes data      ====v====
across network connections, using TCP or UDP protocol.            \  W  /
It is designed to be a reliable "back-end" tool that can          |     |     _
be used directly or easily driven by other programs and           / ___ \    /
scripts.  At the same time, it is a feature-rich network         / /   \ \  |
debugging and exploration tool, since it can create almost      (((-----)))-'
any kind of connection you would need and has several            /
interesting built-in capabilities.  Netcat, or "nc" as the      (      ___
actual program is named, should have been supplied long ago      \__.=|___E
as another one of those cryptic but standard Unix tools.                /

Some of netcat's major features are:

	Outbound or inbound connections, TCP or UDP, to or from any ports
	Full DNS forward/reverse checking, with appropriate warnings
	Ability to use any local source port
	Ability to use any locally-configured network source address
	Built-in port-scanning capabilities, with randomizer
	Can read command line arguments from standard input
	Slow-send mode, one line every N seconds
	Hex dump of transmitted and received data
	Ability to let another program service established connections
	Optional telnet-options responder

A very short list of potential uses:

	Script backends
	Scanning ports and inventorying services, automated probes
	Backup handlers
	File transfers
	Server testing, simulation, debugging, and hijacking
	Firewall testing
	Proxy gatewaying
	Network performance testing
	Address spoofing tests
	Protecting X servers
	1001 other uses you'll likely come up with

Changes between the 1.10 release and release 2.00:

	Autoconfiscation
	Source code easier to read
	Removed DNS checking, too complicated and interacted badly with IPv6
	Removed source-routing, nobody enables it anymore :-)
	Support for IPv6
	Multi-line input for port scanning
	Quit-upon-end-of-input

Changes between the 1.00 release and release 1.10:

	Better portability -- updated generic.h and Makefile [thanx folks!]
	Indication of local-end interface address on inbound connections
	That's *Dave* Borman's telnet, not Paul Borman...
	Better indication of DNS errors
	Total byte counts printed if -v -v is used
	A bunch of front-end driver companion programs and scripts
	Better handling of stdin arguments-plus-data
	Hex-dump feature
	Telnet responder
	Program exec works inbound or outbound now

Netcat and the associated package was written by *Hobbit* as a product
of Avian Research, and the last version he released is available in full
source form with no restrictions save an obligation to give credit where
due.  Get it via anonymous FTP at avian.org:/src/hacks/nc110.tgz
which is a gzipped tar file and not to be confused with its version 1.00
precursor, nc100.tgz.  Other distribution formats can be accomodated upon
request.  Netcat is also mirrored at the following [faster] sites:

	zippy.telcom.arizona.edu:/pub/mirrors/avian.org/hacks/nc110.tgz
	ftp.sterling.com:/mirrors/avian.org/src/hacks/nc110.tgz
	coast.cs.purdue.edu:/pub/tools/unix/netcat/nc110.tgz
	ftp.rge.com:/pub/security/coast/mirrors/avian.org/netcat/nc110.tgz

This release is not an attempt to steal *Hobbit*'s merits as Netcat's
author, but rather to keep an extraordinarily useful tool in pace with
the changes in the Internet, and to make an extraordinarily instructive
piece of code even more so.

Note that there is another renewed version of Netcat which is included
in OpenBSD.  These two are not related; this version does keep most of
the original source code (albeit with renamed variables/functions and
updated/edited comments), while OpenBSD's is said to be a complete
rewrite.  OpenBSD's version lacks some features (hexdump, line-by-line,
multiplexing) but has some more (AF_UNIX sockets and SOCKS support).