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Feb. 14, 1999
_______________________________________________________________________
See the Happy Hacker web site at http://www.happyhacker.org
Your local firewall blocks you? Try http://happyhacker.org
Svenska:
http://w1.340.telia.com/~u34002171/hhd/gtmhh/svenska/hhdsvensk.html
_______________________________________________________________________

Opening Comments
URLs
Reader Submissions
More Trojans
Web Server for 95
A little bit about netcat
Perl Corner
Editor's Comments

******************************************************************
Opening Comments

Here's another edition of the digest.  Some recent news stories,
via The Hacker News Network, have shown what can happen if you
try to hack into computers without permission.  Analyzer, a 20
yr old from Isreal, was indicted for his hacks of the Pentagon
and NASA.  On top of that, a 15 yr old from Vienna, VA, was
_arrested_ for doing thousands of dollars worth of damage to
systems at Clemson University.  Know how he got in initially?
An 18 yr old Computer Science student gave the kid his USERNAME
AND PASSWORD!!

******************************************************************
URLs

The Nessus Project
http://www.nessus.org/

VanDyke Technologies...some good tools here...
http://www.vandyke.com/

The Freefire Project
http://sites.inka.de/sites/lina/freefire-l/index.en.html
**I know it's Unix-oriented, but it's still a good place
to start...

Don't believe everything you read (URL wraps...)
http://dailynews.yahoo.com/headlines/technology/zdnet/story.html
?s=n/zdnn/technology/19981223/199812231303

Self-proclaimed "hacker" hacks the media
http://www.wired.com/news/news/culture/story/17789.html

******************************************************************
Reader Submissions

From: "Anonymous"
Subj: BO question

Hello

I am using BO and the help file for all the commands isn't that
descriptive.  Is there someone who has a help file that would help me
out with some of the commands?  I am looking for help especially with
the copy command.

Thank You
Java

[Editor:  I don't have BO...no, seriously, I don't!!  ;-)
Anyway, I am sure that there are plenty of help files out there.
If another reader would be kind enough to send a URL in...]

From: MadMan <madman593@yahoo.com>
Subj: just wanted to let you know

just wanted to let you know that the "space lan" link in your last
digest was wrong.  the correct address is

http://cnn.com/TECH/space/9902/01/space.lan.idg/index.html

=================================
i've got a question.  i finally got the hardware for a lan and am
trying to connect a win98 box and redhat 5.1 to a freebsd 3.0 box.
what files would i need to configure on each.  thank you.

]v[ad]v[an

[Editor:  Hhhhmmm...thanks for being alert, but the link is, in
fact, correct.  The index.html page is simply the default.  I
clicked on the link in the HHD, and I was presented with the
page immediately.  Now, that aside...to your LAN question.  I
hope that there are readers out there with who can help...and
I'd really appreciate it if one or more would put the info on a
web page and send me the URL!!]

From:  "Jim Noble" <jimnoble@mindspring.com>
Subj:  RE: Happy Hacker Digest, Windows edition

As a Network Manager, I love to read your digest.  I am keeping a
running list of sites that contain hacking tools *(ie Sam Spade,
L0pht Crack, etc).
I thought you might like to share with your readers.  I am mainly
an NT environment, but I am also moving towards Linux.

You can see my site by viewing
http://jimnoble.home.mindspring.com/security.htm .

Happy hunting...

Thank you,
Jim Noble

[Editor:  Thanks!  And I'm glad to see sysadmins and network
managers read the Digest!!]

From: Geoffrey Greene <teiresias@monmouth.com>
Subj: Thanks

Hi,
I would like you to print a response to the enourmous amounts of
responses. Number One. STOP. I figured it out. Number Two. Thanks
to all the people who sent me suggestions and tips, they were all
helpful. If I have any other questions I now know where to send
my query. Thanks for the support.
Geoff

[Editor:  Sometimes, you need to be careful what you wish for!!]

******************************************************************
More Trojans

From:  The Reaper <thereaper666@gmx.net>
Subj:  Trojans

Here I am again.
Thanx for the perl url first.
The reason for my mail is a big collection of Trojans I found, I
thought you may want to warn your readers, it are more then I would
have expected.
Well, check out (NOTE:  The URL wraps...)
http://www.hackcity.com/public/version_1/security/win958/
win958_trojen.html

Bye
TheReaper

******************************************************************
Web Server for 95

From:  "Dennis Wildbore" <denniswildbore@hotmail.com>
Subj:  Web servers for 95

Hello,

I have found a really good and small(67k) web server
for windows 95. It's called tinyweb and can be obtained
at http://www.ritlabs.com/tinyweb/ . Oya it is free
and it runs in the background and it works really well
with perl for your cgi scripts.

Dennis W.
******************************************************************
A little bit about netcat

A while back, I wrote a Guide To (mostly) Harmless Hacking about
using telnet.  A copy of that Guide can be found at:

http://www.patriot.net/users/carvdawg/telguide.txt

In that Guide, I also briefly discussed a nice little app called
netcat, from Weld Pond of L0pht.  Recently a reader asked me
to provide a brief "how-to" on this amazing little tool.

First of all, to get the 95/NT version of netcat, go to:

http://www.l0pht.com/~weld/netcat

>From this page, you should read the readme files for both the
95/NT and the Unix versions...I suggest you read them.  I will
try to run through the various switches and provide some
examples.

Some of the switches for netcat are:

-d  detach, or stealth mode
-e<prog> program to execute upon connection
-l  listen for connections
-L  same as -l, but listen again after the
  connection is closed
-n  specific numeric addresses; don't do a DNS lookup
-o<logfile> get a hexdump of the action
-p<port> port to bind to
-s<ip addr> bind to a specific source IP address
-t  Answer telnet negotiations upon connection
-u   specify UDP
-v   verbose mode (add another -v for even more...)
-w  specify timeout

Now, let's look at you to use this tool.  From here on out,
the following examples will assume that you've copied the netcat
executable, nc.exe, into a directory in your PATH; c:\windows
for 95/98, or c:\winnt\system32 for NT.  Also, the examples
will be demonstrated from the command line, or the c:\> prompt.

For help, type:

c:\>nc -h

This will display the switches above, plus some others.

To connect to a port on a server, or to check if the port is
open:

c:\>nc -v <IP or hostname> <port>

or

c:\>nc -v -n <IP addr> <port>

You can use this to connect to ports like 21, 25, and 110, and
the commands you enter will be sent to the server.  Notice that
the second command above uses the '-n' switch to restrict netcat
to IP addresses and not use DNS lookups.

You can use netcat as a simple finger client by typing:

c:\>nc -v <host> 79 < user.txt

For this example to work, you need to have a file on your
computer called 'user.txt'.  The file simply contains the
username you are interested in.  You can also add '> log.txt'
to the end of the command to capture the output of the command
to a file called 'log.txt'.

You can download web pages with netcat.  I do this sometimes,
using two files.  The first file is called 'get.txt', and
contains the command that I want netcat to send to the HTTP
server:

-----  begin get.txt  -----
GET / HTTP/1.0

-----  end get.txt  -----

**NOTE:  The '/' is the default web page on the server, usually
'index.html' or 'default.asp'.  The text on the first line MUST
be followed by 2 carriage returns (ie, hit Enter twice) for this
to work.  That's how the HTTP protocol works.  If you were writing
this in Perl, the code you would use would look like:

print $socket "GET / HTTP/1.0\n\n";

The second file is a batch file:

-----  begin jam.bat  -----
@echo off
nc -v %1 80 < get.txt > index.txt
notepad index.txt
-----  end jam.bat  -----

Pretty simple.  You run this batch file by typing:

c:\>jam www.happyhacker.org

The nc command will connect to port 80 on the server you
entered as a argument, send the contents of 'get.txt',
which is our HTTP command, and store the results in
'index.txt'.  Then, the contents of 'index.txt' will be
displayed in a Notepad window.  This allows you to see the
headers and source of the web page, without worrying about
malicious JavaScript or VBScript...and you can see the
comments, if there are any.

To create a simple server:

c:\>nc -l -p 1234 < file

This example listens on port 1234 on you computer, and when
someone connects to that port, the contents of the file named
'file' are sent to the client.  You can use this as a simple
finger server...simply use different files of edit the contents
of 'file' to suit your needs.

A very simple web server would look like:

c:\>nc -L -d -p 80 < file

Where file contains the text you want to send to the browser.
It's not the greatest web browser, but it works!

A little more sophisticated server, like a telnet server, looks
like:

c:\>nc -L -d -p 525 -t -e cmd.exe

This command tells netcat to listen for connections on port 525,
answer telnet negotiations, and execute cmd.exe (if you are on
95, you'll want to use 'command.com') upon a connection.  The
'-d' runs the connection in stealth mode.  One thing you need
to keep in mind is this...this is basically a telnet server that
doesn't ask for a username and password.  When someone connects
to port 525 (in this case...you can use any port you choose)
they are presented with a prompt on YOUR MACHINE!  So you can
see how this can make a pretty dangerous trojan...

When you're using netcat for network testing, you can include
the '-o' switch along with the name of a log file in order to
get a hex and ASCII record of the communications.

Now for the reader challenge...what innovative ways do YOU
use netcat?  If you have another way of using netcat, something
different what's been presented here, or something other than
sending fake email through port 25, let me know!  I'll post
some of the most unique ways of using netcat in an upcoming
digest!

******************************************************************
Perl Corner

Okay, in this edition of the Perl Corner, we're going to create
a server.  That's right...we're going to write code that will
sit and listen for connections, and when one is detected, will
respond in a predetermined fashion.  For this Perl Corner, we'll
write a finger server to go along with our finger client from
the last edition.

First, a quick word about client-server computing.  This is the
model adopted by the Internet...there are servers out there, just
waiting for connections.  They sit and 'listen' all the time.  On
your computer is the client...telnet, ftp, even your browser.
These tools request services and support from the servers.

That being said, here's how our server is going to work...first,
we create a server socket that will listen for connections.  The
server socket listens on a specific port (in other words, it's
bound to that port) for incoming connections.  Ports below 1024
are referred to as 'well-known' ports...see RFC 1700 for a list
of 'well-known' ports.  As we are creating a finger server, we
will bind our server to the 'well-known' finger port, 79.  Once
a connection is made, we will service that connection, and then
close the socket connection to the client.  Simple.  In servicing
the connection, all we expect to get is a single input...a
username to be queried.  In this example, all we do is output the
hostname, IP address and query back to the client.

-----  begin fingerd.pl  -----
#! c:\perl\bin\perl.exe
# Simple finger daemon
use IO::Socket;

# listen on the well-known finger port
my $port = 79;

# create a server socket to listen for
# connections
$sock = new IO::Socket::INET (LocalPort => $port,
                       Proto => 'tcp',
                              Listen => 5,
                              Reuse => 1) ||
     die "Socket error:  $!\n" unless $sock;

print "Finger server started...\n";

# listen for connections
# don't disconnect after the first connection
# just keep listening
while (1) {

# new connection accepted
  $new_sock = $sock->accept();

# get the IP of the client, and the hostname
  $ip = $new_sock->peerhost();
  ($name,$alias,$addrtype,$length,$new_addr) =
      gethostbyaddr(inet_aton($ip),AF_INET);

# print the hostname and IP to the screen
  print "Connection from:  $name [$ip]\n";

# get the query from the client and display it
  $query = <$new_sock>;
  print "Query: $query\n";

# send a message back to the client
  print $new_sock "$name [$ip] queried $query\n";

# close the socket
  close($new_sock);
}
-----  end fingerd.pl  -----

Great!  What've we've got is a very simple finger server (daemon
for the Unix-philes among us).  From here, you can modify the
info that is sent back to the client.  Just copy the line that
starts with "print $new_sock" and add what information you want to
appear to the client between quotes.  Be sure to add the new line
character (\n) at the end of each line.

Then, try testing the server.  Run it on your system, and have
your friends connect via:
(a) telnet,
(b) the finger client from the last edition of the HHD, or
(c) any other finger client.

NOTE:  If your computer is not listed in the DNS tables with
some easy-to-remember name, then the finger command would need
to look something like this:

finger [user]@[a.b.c.d]

where [user] = the username you are querying, and [a.b.c.d] is
the IP address of the computer that the above finger server is
running on.  If you are using the finger client from the last
edition of the HHD, the command would look like:

perl finger.pl [user]@[a.b.c.d]

Other ways to adapt this server:
-> use if-else statements to display different text or take
   various actions based upon the username that is queried.
   Here's a quick code snippet to do just that:
   ----  begin code  ----
   if ($query =~ m/root/i) {
     print $new_sock "You've fingered the root account.\n";
   }
   elsif ($query =~ m/test/i) {
     print $new_sock "You've fingered the test account.\n";
   }
   else {
     print $new_sock "User $query unknown.\n";
   }
   ----  end code  ----
-> remove the code that sends a response back to the client, and
   you have a rudimentary port scan detector!  Once you have the
   IP of the person who scanned you, you can use code from the
   last Perl Corner to port scan and finger them!
-> modify the above code to do specific things, such as log the
   connection to a file, or to the EventLog (for sysadmins who
   are using audit reduction and analysis tools).
-> far more complicated versions of this server could open a file
   based on the username queried, and output the contents of
   that file to the client, much the same way a .plan or .profile
   file is used on Unix accounts.  Or, a connection could be made
   to a backend database for the information...

PERL TIP
I wanted to add a quick note here about making things easier for
yourself when running Perl scripts, like the finger client from
the last edition of the HHD.  By now, most of you have seen that
you have to type "finger.pl user@host" or "perl finger.pl
user@host" to execute the script.  Well, if you use the script a
lot, that can be a lot of typing, can't it.  We have another tool
that we can use...batch files!

Now, let's say that your finger.pl script is in the c:\perl
directory.  Using the DOS prompt, go to that directory, and
type "notepad finger.bat".  A Notepad window will open, and you
should choose "yes" on the dialogue box to create the file (if it
doesn't already exist).  This file should contain the lines:

-----  begin finger.bat -----
@echo off
c:\perl\bin\perl.exe finger.pl %1
----- end finger.bat -----

That's it.  Save the file, and go back to the command line.  Type
"finger user@host".  The batch file will call the Perl script and
pass the argument, in this case "user@host", to the script.

For other tips, check out:

http://www.patriot.net/users/carvdawg/perl.html

******************************************************************
Editor's Comments

That's it.  Let me close by saying that I really enjoyed the
recent issue of the Unix version of the digest.

If you're going to help out and answer a question posted here,
please feel free to do so...and make sure that you send it to the
person who wrote the question.  I can't tell you how many answers
I've received over the past couple of weeks, and I'm the only one
in the recipient list of the email!  Also, if you have a question,
please be clear about it...give enough info to support the
question, use decent spelling/grammar/punctuation.  I'm getting a
lot of email just from the Digest now, and if I can't understand
what it is you want, I have to just delete it.  Help me to help
you!!

___________________________________________________________________


   
 

This is a list devoted to *legal* hacking! If you plan to use any
information in this Digest or at our Web site to commit crime, go away!
Foo on you! Don't email us bragging about any crimes you may have committed.
We mean it. 

For Windows questions, email keydet89@yahoo.com or editor@cmeinel.com
For Unix questions, contact unixeditor@cmeinel.com.
For Macs, email Strider <s.corinth@iname.com> 

Happy Hacker staff: Unix editor, <unixeditor@cmeinel.com>;
Windows editor, Keydet89 <editor@cmeinel.com>; postmasters Jonathan D.
Zerulik and William Lewis <>; Hacker Wargame Director,
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Grand Pooh-bah: Carolyn Meinel <>

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