Hacking For Dummies 2, Hacking and IT E-Book Dump Release
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Hacking for Dummies
Contents of Volume 2:
Internet for Dummies
Linux!
Introduction to TCP/IP
Port Surfing!
____________________________________________________________
GUIDE TO (mostly) HARMLESS HACKING
Vol. 2 Number 1
Internet for Dummies -- skip this if you are a Unix wizard. But if you read on
you’ll get some more kewl hacking instructions.
____________________________________________________________
The six Guides to (mostly) Harmless Hacking of Vol. 1 jumped immediately into
how-to hacking tricks. But if you are like me, all those details of probing ports
and playing with hypotheses and pinging down hosts gets a little dizzying.
So how about catching our breath, standing back and reviewing what the heck it
is that we are playing with? Once we get the basics under control, we then can
move on to serious hacking.
Also, I have been wrestling with my conscience over whether to start giving you
step-by-step instructions on how to gain root access to other peoples’ computers.
The little angel on my right shoulder whispers, “Gaining root without permission
on other people’s computers is not nice. So don’t tell people how to do it.” The
little devil on my left shoulder says, “Carolyn, all these hackers think you don’t
know nothin’! PROOVE to them you know how to crack!” The little angel says,
“If anyone reading Guide to (mostly) Harmless Hacking tries out this trick, you
might get in trouble with the law for conspiracy to damage other peoples’
computers.” The little devil says, “But, Carolyn, tell people how to crack into root
and they will think you are KEWL!”
So here’s the deal. In this and the next few issues of Guide to (mostly) Harmless
Hacking I’ll tell you several ways to get logged on as the superuser in the root
account of some Internet host computers. But the instructions will leave a thing or
two to the imagination.
My theory is that if you are willing to wade through all this, you probably aren’t
one of those cheap thrills hacker wannabes who would use this knowledge to do
something destructive that would land you in jail.
*****************************
Technical tip: If you wish to become a *serious* hacker, you’ll need Linux (a
freeware variety of Unix) on your PC. One reason is that then you can crack into
root legally all you want -- on your own computer. It sure beats struggling around
on someone else’s computer only to discover that what you thought was root was
a cleverly set trap and the sysadmin and FBI laugh at you all the way to jail.
Linux can be installed on a PC with as little as a 386 CPU, only 2 Mb RAM and
as little as 20 MB of hard disk. You will need to reformat your hard disk. While
some people have successfully installed Linux without trashing their
DOS/Windows stuff, don’t count on getting away with it. Backup, backup,
backup!
*****************************
*****************************
You can go to jail warning: Crack into root on someone else’s computer and the
slammer becomes a definite possibility. Think about this: when you see a news
story about some hacker getting busted, how often do you recognize the name?
How often is the latest bust being done to someone famous, like Dark Tangent or
se7en or Emmanuel Goldstein? How about, like, never! That’s because really
good hackers figure out how to not do stupid stuff. They learn how to crack into
computers for the intellectual challenge and to figure out how to make computers
safe from intruders. They don’t bull their way into root and make a mess of
things, which tends to inspire sysadmins to call the cops.
*********************************
Exciting notice: Is it too boring to just hack into your own Linux machine? Hang
in there. Ira Winkler of the National Computer Security Association, Dean
Garlick of the Space Dynamics Lab of Utah State University and I are working on
setting up hack.net, a place where it will be legal to break into computers. Not
only that, we’re looking for sponsors who will give cash awards and scholarships
to those who show the greatest hacking skills. Now does that sound like more
phun than jail?
*****************************
So, let’s jump into our hacking basics tutorial with a look at the wondrous
anarchy that is the Internet.
Note that these Guides to (mostly) Harmless Hacking focus on the Internet. That
is because there are many legal ways to hack on the Internet. Also, there are over
10 million of these readily hackable computers on the Internet, and the number
grows every day.
Internet Basics
No one owns the Internet. No one runs it. It was never planned to be what it is
today. It just happened, the mutant outgrowth of a 1969 US Defense Advanced
Research Projects Agency experiment.
This anarchic system remains tied together because its users voluntarily obey
some basic rules. These rules can be summed up in two words: Unix and TCP/IP
(with a nod to UUCP). If you understand, truly understand Unix and TCP/IP (and
UUCP), you will become a fish swimming in the sea of cyberspace, an
Uberhacker among hacker wannabes, a master of the Internet universe.
To get technical, the Internet is a world-wide distributed
computer/communications network held together by a common communications
standard, Transmission Control Protocol/Internet Protocol (TCP/IP) and a bit of
UUCP. These standards allow anyone to hook up a computer to the Internet,
which then becomes another node in this network of the Internet. All that is
needed is to get an Internet address assigned to the new computer, which is then
known as an Internet "host," and tie into an Internet communications link. These
links are now available in almost all parts of the world.
If you use an on-line service from your personal computer, you, too, can
temporarily become part of the Internet. There are two main ways to hook up to
an on-line service.
There is the cybercouch potato connection that every newbie uses. It requires
either a point-to-point (PPP) or SLIPconnection, which allows you to run pretty
pictures with your Web browser. If you got some sort of packaged software from
your ISP, it automatically gives you this sort of connection.
Or you can connect with a terminal emulator to an Internet host. This program
may be something as simple as the Windows 3.1 “Terminal” program under the
“Accessories” icon. Once you have dialed in and connected you are just another
terminal on this host machine. It won’t give you pretty pictures. This connection
will be similar to what you get on an old-fashioned BBS. But if you know how to
use this kind of connection, it could even give you root access to that host.
But how is the host computer you use attached to the Internet? It will be running
some variety of the Unix operating system. Since Unix is so easy to adapt to
almost any computer, this means that almost any computer may become an
Internet host.
For example, I sometimes enter the Internet through a host which is a Silicon
Graphics Indigo computer at Utah State University. Its Internet address is
fantasia.idec.sdl.usu.edu. This is a computer optimized for computer animation
work, but it can also operate as an Internet host. On other occasions the entry
point used may be pegasus.unm.edu, which is an IBM RS 6000 Model 370. This
is a computer optimized for research at the University of New Mexico.
Any computer which can run the necessary software -- which is basically the
Unix operating system -- has a modem, and is tied to an Internet communications
link, may become an Internet node. Even a PC may become an Internet host by
running one of the Linux flavors of Unix. After setting it up with Linux you can
arrange with the ISP of your choice to link it permanently to the Internet.
In fact, many ISPs use nothing more than networked PCs running Linux!
As a result, all the computing, data storage, and sending, receiving and
forwarding of messages on the Internet is handled by the millions of computers of
many types and owned by countless companies, educational institutions,
governmental entities and even individuals.
Each of these computers has an individual address which enables it to be reached
through the Internet if hooked up to a appropriate communications link. This
address may be represented in two ways: as a name or a number.
The communications links of the Internet are also owned and maintained in the
same anarchic fashion as the hosts. Each owner of an Internet host is responsible
for finding and paying for a communications link that will get that host tied in
with at least one other host. Communications links may be as simple as a phone
line, a wireless data link such as cellular digital packet data, or as complicated as
a high speed fiber optic link. As long as the communications link can use TCP/IP
or UUCP, it can fit into the Internet.
Thus the net grows with no overall coordination. A new owner of an Internet host
need only get permission to tie into one communications link to one other host.
Alternatively, if the provider of the communications link decides this host is, for
example, a haven for spammers, it can cut this “rogue site” off of the Internet.
The rogue site then must snooker some other communications link into tying it
into the Internet again.
The way most of these interconnected computers and communications links work
is through the common language of the TCP/IP protocol. Basically, TCP/IP
breaks any Internet communication into discrete "packets." Each packet includes
information on how to rout it, error correction, and the addresses of the sender
and recipient. The idea is that if a packet is lost, the sender will know it and
resend the packet. Each packet is then launched into the Internet. This network
may automatically choose a route from node to node for each packet using
whatever is available at the time, and reassembles the packets into the complete
message at the computer to which it was addressed.
These packets may follow tortuous routes. For example, one packet may go from
a node in Boston to Amsterdam and back to the US for final destination in
Houston, while another packet from the same message might be routed through
Tokyo and Athens, and so on. Usually, however, the communications links are
not nearly so torturous. Communications links may include fiber optics, phone
lines and satellites.
The strength of this packet-switched network is that most messages will
automatically get through despite heavy message traffic congestion and many
communications links being out of service. The disadvantage is that messages
may simply disappear within the system. It also may be difficult to reach desired
computers if too many communications links are unavailable at the time.
However, all these wonderful features are also profoundly hackable. The Internet
is robust enough to survive -- so its inventors claim -- even nuclear war. Yet it is
also so weak that with only a little bit of instruction, it is possible to learn how to
seriously spoof the system (forged email) or even temporarily put out of
commission other people's Internet host computers (flood pinging, for example.)
On the other hand, the headers on the packets that carry hacking commands will
give away the account information from which a hacker is operating. For this
reason it is hard to hide perfectly when on the Internet.
It is this tension between this power and robustness and weakness and potential
for confusion that makes the Internet a hacker playground.
For example, HERE IS YOUR HACKER TIP YOU’VE BEEN WAITING FOR
THIS ISSUE:
ftp://ftp.secnet.com
This ftp site was posted on the BUGTRAQ list, which is dedicated to discussion
of Unix security holes. Moderator is Aleph One, who is a genuine Uberhacker. If
you want to subscribe to the BUGTRAQ, email LISTSERV@netspace.org with
message “subscribe BUGTRAQ.”
Now, back to Internet basics.
History of Internet
As mentioned above, the Internet was born as a US Advanced Research Projects
Agency (ARPA) effort in 1969. Its inventors called it ARPANET. But because of
its value in scientific research, the US National Science Foundation (NSF) took it
over in 1983. But over the years since then it gradually evolved away from any
single source of control. In April 1995 NSF cut the last apron strings. Now the
Internet is run by no one. It just happens and grows out of the efforts of those who
play with it and struggle with the software and hardware.
Nothing at all like this has ever happened before. We now have a computer
system with a life of its own. We, as hackers, form a big part of the mutation
engine that keeps the Internet evolving and growing stronger. We also form a big
part of the immune system of this exotic creature.
The original idea of ARPANET was to design a computer and communications
network that would eventually become so redundant, so robust, and so able to
operate without centralized control, that it could even survive nuclear war. What
also happened was that ARPANET evolved into a being that has survived the end
of government funding without even a blip in its growth. Thus its anarchic
offspring, the Internet, has succeeded beyond the wildest dreams of its original
architects.
The Internet has grown explosively, with no end in sight. At its inception as
ARPANET it held only 4 hosts. A quarter of a century later, in 1984, it contained
only 1000 hosts. But over the next 5 years this number grew tenfold to 10,000
(1989). Over the following 4 years it grew another tenfold to 1 million (1993).
Two years later, at the end of 1995, the Internet was estimated to have at least 6
million host computers. There are probably over 10 million now. There appears to
be no end in sight yet to the incredible growth of this mutant child of ARPANET.
In fact, one concern raised by the exponential growth in the Internet is that
demand may eventually far outrace capacity. Because now no entity owns or
controls the Internet, if the capacity of the communications links among nodes is
too small, and it were to become seriously bogged down, it might be difficult to
fix the problem.
For example, in 1988, Robert Morris, Jr. unleashed a "virus"-type program on the
Internet commonly known as the “Morris Worm.” This virus would make copies
of itself on whatever computer it was on and then send copies over
communications links to other Internet hosts. (It used a bug in sendmail that
allowed access to root, allowing the virus to act as the superuser).
Quickly the exponential spread of this virus made the Internet collapse from the
communications traffic and disk space it tied up.
At the time the Internet was still under some semblance of control by the National
Science Foundation and was connected to only a few thousand computers. The
Net was shut down and all viruses purged from its host computers, and then the
Net was put back into operation. Morris, meanwhile, was put in jail.
There is some concern that, despite improved security measures (for example,
"firewalls"), someone may find a new way to launch a virus that could again shut
down the Internet. Given the loss of centralized control, restarting it could be
much more time-consuming if this were to happen again.
But reestablishing a centralized control today like what existed at the time of the
“Morris Worm” is likely to be impossible. Even if it were possible, the original
ARPANET architects were probably correct in their assessment that the Net
would become more susceptible for massive failure rather than less if some
centralized control were in place.
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