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GUIDE TO (mostly) HARMLESS HACKING
Vol 3 Number 4
How to Read Email Headers and Find Internet Hosts
Warning: flamebait enclosed!

OK, OK, you 31337 haxors win. I'm finally releasing the next in our series of Guides oriented toward the intermediate hacker. Now some of you may think that headers are too simple or boring to waste time on. However, a few weeks ago I asked the 3000+ readers of the Happy Hacker list if anyone could tell me exactly what email tricks I was playing in the process of mailing out the Digests. But not one person replied with a complete answer -- or even 75% of the answer -- or even suspected that for months almost all Happy Hacker mailings have doubled as protests. The targets: ISPs offering download sites for email bomber programs. Conclusion: it is time to talk headers!

In this Guide we will learn:
· what is a header
· why headers are fun
· how to see full headers
· what all that stuff in your headers means
· how to get the names of Internet host computers from your headers
· the foundation for understanding the forging of email and Usenet posts, catching the people who forge headers, and the theory behind those email bomber programs that can bring an entire Internet Service Provider (ISP) to its knees.

This is a Guide you can make at least some use of without getting a shell account or installing some form of Unix on your home computer. All you need is to be able to send and receive email, and you are in business. However, if you do have a shell account, you can do much more with deciphering headers. Viva Unix!

Headers may sound like a boring topic. Heck, the Eudora email program named the button you click to read full headers "blah blah blah." But all those guys who tell you headers are boring are either ignorant -- or else afraid you'll open a wonderful chest full of hacker insights. Yes, every email header you check out has the potential to unearth a treasure hidden in some back alley of the Internet.

Now headers may seem simple enough to be a topic for one of our Beginners' Series Guides. But when I went to look up the topic of headers in my library of manuals, I was shocked to find that most of them don't even cover the topic. The two I found that did cover headers said almost nothing about them. Even the relevant RFC 822 is pretty vague. If any of you super-vigilant readers looking for flame bait happen to know of any literature that *does* cover headers in detail, please include that information in your tirades!

*********************************************
Technical tip: Information relevant to headers may be extracted from Requests for Comments (RFCs) 822 (best), as well as 1042, 1123, 1521 and 1891 (not a complete list). To read them, take your Web browser to http://altavista.digital.com and search for "RFC 822" etc.
*********************************************

Lacking much help from manuals, and finding that RFC 822 didn't answer all my questions, the main way I researched this article was to send email back and forth among some of my accounts, trying out many variations in order to see what kinds of headers they generated. Hey, that's how real hackers are supposed to figure out stuff when RTFM (read the fine manual) or RTFRFC (read the fine RFC)doesn't tell us as much as we want to know. Right? One last thing. People have pointed out to me that every time I put an email address or domain name in a Guide to (mostly) Harmless Hacking, a zillion newbies launch botched hacking attacks against these. All email addresses and domain names below have been fubarred.

************************************************
Newbie note: The verb "to fubar" means to obscure email addresses and Internet host addresses by changing them. Ancient tradition holds that it is best to do so by substituting "foobar" or "fubar" for part of the address.
************************************************

WHAT ARE HEADERS?

If you are new to hacking, the headers you are used to seeing may be incomplete. Chances are that when you get email it looks something like this:
From: Vegbar Fubar <fooha@ifi.foobar.no>
Date: Fri, 11 Apr 1997 18:09:53 GMT
To: <script language="JavaScript"><!-- var name = "cmeinel"; var domain = "cmeinel.com"; document.write('<a href=\"mailto:' + name + '@' + domain + '\">'); document.write(name + '@' + domain + '</a>'); // --></script>

But if you know the right command, suddenly, with this same email message, we are looking at tons and tons of stuff:
Received: by o200.fooway.net (950413.SGI.8.6.12/951211.SGI)
for techbr@fooway.net id OAA07210; Fri, 11 Apr 1997 14:10:06 -0400
Received: from ifi.foobar.no by o200.fooway.net via ESMTP
(950413.SGI.8.6.12/951211.SGI) for <> id OAA18967; Fri, 11 Apr 1997 14:09:58 -0400
Received: from gyllir.ifi.foobar.no (2234@gyllir.ifi.foobar.no
[129.xxx.64.230]) by ifi.foobar.no with ESMTP (8.6.11/ifi2.4)
id <UAA24351@ifi.foobar.no> for <> ; Fri, 11 Apr 1997 20:09:56 +0200
From: Vegbar Fubar <fooha@ifi.foobar.no>
Received: from localhost (Vegbarha@localhost) by gyllir.ifi.foobar.no ; Fri, 11 Apr 1997 18:09:53 GMT
Date: Fri, 11 Apr 1997 18:09:53 GMT
Message-Id: <199704111809.13156.gyllir@ifi.foobar.no>
To: <script language="JavaScript"><!-- var name = "cmeinel"; var domain = "cmeinel.com"; document.write('<a href=\"mailto:' + name + '@' + domain + '\">'); document.write(name + '@' + domain + '</a>'); // --></script>

Hey, have you ever wondered why all that stuff is there and what it means? We'll return to this example later in this tutorial. But first we must consider the burning question of the day:

WHY ARE HEADERS FUN?

Why bother with those "blah blah blah" headers? They are boring, right? Wrong! 1) Ever hear a wannabe hacker complaining he or she doesn't have the addresses of any good computers to explore? Have you ever used one of those IP scanner programs that find valid Internet Protocol addresses of Internet hosts for you? Well, you can find gazillions of valid addresses without the crutch of one of these programs simply by reading the headers of emails.
2) Ever wonder who really mailed that "Make Money Fast" spam? Or who is that klutz who email bombed you? The first step to learning how to spot email forgeries and spot the culprit is to be able to read headers.
3) Want to learn how to convincingly forge email? Do you aspire to write automatic spam or email bomber programs? (I disapprove of spammer and email bomb programs, but let's be honest about the kinds of knowledge their creators must draw upon.) The first step is to understand headers.
4) Want to attack someone's computer? Find out where best to attack from the headers of their email. I disapprove of this use, too. But I'm dedicated to telling you the truth about hacking, so like it or not, here it is.

HOW CAN YOU SEE FULL HEADERS?

So you look at the headers of your email and it doesn't appear have any good stuff whatsoever. Want to see all the hidden stuff? The way you do this depends on what email program you are using. The most popular email program today is Eudora. To see full headers in Eudora, just click the "blah, blah, blah" button on the far left end of the tool bar.

The Netscape web browser includes an email reader. To see full headers, click on Options, then click the "Show All Headers" item. Sorry, I haven't looked into how to do that with Internet Explorer. Oh, no, I can see the flames coming, how dare I not learn the ins and outs of IE mail! But, seriously, IE is a dangerously insecure Web browser because it is actually a Windows shell. So no matter how often Microsoft patches its security flaws, chances are you will be hurt by it one of these days. Just say "no" to IE.

Another popular email program is Pegasus. Maybe there is an easy way to see full headers in Pegasus, but I haven't found it. The hard way to see full headers in Pegasus -- or IE -- or any email program -- is to open your mail folders with Wordpad. It is included in the Windows 95 operating system and is the best Windows editing program I have found for handling documents with lots of embedded control characters and other oddities.

The Compuserve 3.01 email program automatically shows full headers. Bravo, Compuserve!

Pine is the most popular email program used with Unix shell accounts. Since in order to be a real hacker you will sooner or later be using Unix, now may be a great time to start using Pine.

*************************************************
Newbie note: Pine stands for Pine Is No longer Elm, a tribute to the really, truly ancient Elm email program (which is still in use). Both Pine and Elm date back to ARPAnet, the US Defense Advanced Research Projects Agency computer network that eventually mutated into today's Internet.
*************************************************

If you have never used Pine before, you may find it isn't as easy to use as those glitzy Windows email programs. But aside from its amazing powers, there is a really good reason to learn to compose email in Pine: you get practice using pico editor commands. If you want to be a real hacker, you will be using the pico editor (or another editor that uses similar commands) someday when you are writing programs in a Unix shell.

To bring up Pine, at the cursor in your Unix shell simply type in "pine." In Pine, while viewing an email message, you may be able to see full headers by simply hitting the "h" key. If this doesn't work, you will have to go into the Setup menu to enable this command. To do this, go to the main menu and give the command "s" for Setup. Then in the Setup menu choose "c" for Config. On the second page of the Config menu you will see something like this:

PINE 3.91 SETUP CONFIGURATION Folder: INBOX 2 Messages
[ ] compose-rejects-unqualified-addrs
[ ] compose-sets-newsgroup-without-confirm
[ ] delete-skips-deleted
[ ] enable-aggregate-command-set
[ ] enable-alternate-editor-cmd
[ ] enable-alternate-editor-implicitly
[ ] enable-bounce-cmd
[ ] enable-flag-cmd
[X] enable-full-header-cmd
[ ] enable-incoming-folders
[ ] enable-jump-shortcut
[ ] enable-mail-check-cue
[ ] enable-suspend
[ ] enable-tab-completion
[ ] enable-unix-pipe-cmd
[ ] expanded-view-of-addressbooks
[ ] expanded-view-of-folders
[ ] expunge-without-confirm
[ ] include-attachments-in-reply
? Help E Exit Config P Prev - PrevPage
X [Set/Unset] N Next Spc NextPage W WhereIs

You first highlight the line that says "enable-full-header-command" and then press the "x" key. The give "e" to exit saving the change. Once you have done this, when you are reading your email you will be able to see full headers by giving the "h" command.

Elm is another Unix email reading program. It actually gives slightly more detailed headers than Pine, and automatically shows full headers.

WHAT DOES ALL THAT STUFF IN YOUR HEADERS MEAN?

We'll start by taking a look at a mildly interesting full header. Then we'll examine two headers that reveal some interesting shenanigans. Finally we will look at a forged header.

OK, let us return to that fairly ordinary full header we looked at above. We will decipher it piece by piece. First we look at the simple version:

From: Vegbar Fubar <fooha@ifi.foobar.no>
Date: Fri, 11 Apr 1997 18:09:53 GMT
To: <script language="JavaScript"><!-- var name = "cmeinel"; var domain = "cmeinel.com"; document.write('<a href=\"mailto:' + name + '@' + domain + '\">'); document.write(name + '@' + domain + '</a>'); // --></script>

The information within any header consists of a series of fields separated from each other by a "newline" character. Each field consists of two parts: a field name, which includes no spaces and is terminated by a colon; and the contents of the field. In this case the only fields that show are "From:," "Date:," and "To:".

In every header there are two classes of fields: the "envelope," which contains only the sender and recipient fields; and everything else, which is information specific to the handling of the message. In this case the only field that shows which gives information on the handling of the message is the Date field.

When we expand to a full header, we are able to see all the fields of the header. We will now go through this information line by line.

Received: by o200.fooway.net (950413.SGI.8.6.12/951211.SGI)for
techbr@fooway.net id OAA07210; Fri, 11 Apr 1997 14:10:06-0400

This line tells us that I downloaded this email from the POP server at a computer named o200.fooway.net. This was done on behalf of my account with email address of techbr@fooway.net. The (950413.SGI.8.6.12/951211.SGI) part identifies the software name and version running that POP server.

********************************************
Newbie note: POP stands for Post Office Protocol. Your POP server is the computer that holds your email until you want to read it. Usually your the email program on your home computer or shell account computer will connect to port 110 on your POP server to get your email. A similar, but more general protocol is IMAP, for Interactive Mail Access Protocol. Trust me, you will be a big hit at parties if you can hold forth on the differences between POP and IMAP, you big hunk of a hacker, you! (Hint: for more info, RTFRFCs.)
********************************************

Now we examine the second line of the header:

Received: from ifi.foobar.no by o200.fooway.net via ESMTP
(950413.SGI.8.6.12/951211.SGI)for <> id OAA18967; Fri, 11 Apr 1997 14:09:58 -0400

Well, gee, I didn't promise that this header would be *totally* ordinary. This line tells us that a computer named ifi.foobar.no passed this email to the POP server on o200.fooway.net for someone with the email address of . This is because I am piping all email to into the account techbr@fooway.net. Under Unix this is done by setting up a file in your home directory named ".forward" with the address to which you want your email sent. Now there is a lot more behind this, but I'm not telling you. Heh, heh. Can any of you evil geniuses out there figure out the whole story?

"ESMTP" stands for "extended simple mail transfer protocol." The "950413.SGI.8.6.12/951211.SGI" designates the program that is handling my email.

Now for the next line in the header:

Received: from gyllir.ifi.foobar.no (2234@gyllir.ifi.foobar.no
[129.xxx.64.230]) by ifi.foobar.no with ESMTP (8.6.11/ifi2.4) id
<UAA24351@ifi.foobar.no> for <> ; Fri, 11 Apr 1997 20:09:56 +0200

This line tells us that the computer ifi.foobar.no got this email message from the computer gyllir.ifi.foobar.no. These two computers appear to be on the same LAN. In fact, note something interesting. The computer name gyllir.ifi.foobar.no has a number after it, 129.xxx.64.230. This is the numerical representation of its name. (I substituted ".xxx." for three numbers in order to fubar the IP address.) But the computer ifi.foobar.no didn't have a number after its name. How come?

Now if you are working with Windows 95 or a Mac you probably can't figure out this little mystery. But trust me, hacking is all about noticing these little mysteries and probing them (until you find something to break, muhahaha -- only kidding, OK?)

But since I am trying to be a real hacker, I go to my trusty Unix shell account and give the command:

>nslookup ifi.foobar.no
Server: Fubarino.com
Address: 198.6.71.10
Non-authoritative answer:
Name: ifi.foobar.no
Address: 129.xxx.64.2

Notice the different numerical IP addresses between ifi.foobar.no and gyllir.ifi.foobar.no. Hmmm, I begin to think that the domain ifi.foobar.no may be a pretty big deal. Probing around with dig and traceroute leads me to discover lots more computers in that domain. Probing with nslookup in the mode "set type=any" tells me yet more. Say, what does that ".no" mean, anyhow? A quick look at the International Standards Organization (ISO) records of country abbreviations, I see "no" stands for Norway. Aha, it looks like Norway is an arctic land of fjords, mountains, reindeer, and lots and lots of Internet hosts. A quick search of the mailing list for Happy Hacker reveals that some 5% of its almost 4,000 email addresses have the .no domain. So now we know that this land of the midnight sun is also a hotbed of hackers! Who said headers are boring?

On to the next line, which has the name and email address of the sender:

From: Vegbar Fubar <fooha@ifi.foobar.no>
Received: from localhost (Vegbarha@localhost) by gyllir.ifi.foobar.no ; Fri, 11 Apr 1997 18:09:53 GMT

I'm going to do some guessing here. This line says the computer gyllir.ifi.foobar.no got this email message from Vegbar Fubar on the computer "localhost." Now "localhost" is what a Unix computer calls itself. While in a Unix shell, try the command "telnet localhost." You'll get a login sequence that gets you right back into your own account. So when I see that gyllir.ifi.foobar.no got the email message from "localhost" I assume that means the sender of this email was logged into a shell account on gyllir.ifi.foobar.no, and that this computer runs Unix. I quickly test this hypothesis:

> telnet gyllir.ifi.foobar.no
Trying 129.xxx.64.230...
Connected to gyllir.ifi.foobar.no.
Escape character is '^]'.
IRIX System V.4 (gyllir.ifi.foobar.no)

Now Irix is a Unix-type operating system for Silicon Graphics Inc. (SGI) machines. This fits with the name of the POP server software on ifi.foobar.no in the header of (950413.SGI.8.6.12/951211.SGI). So, wow, we are looking at a large network of Norwegian computers that includes SGI boxes. We could find out just how many SGI boxes with patience, scanning of neighboring IP addresses, and use of the Unix dig and nslookup commands. Now you don't see SGI boxes just every day on the Internet. SGI computers are optimized for graphics and scientific computing. So I'm really tempted to learn more about this domain. Oftentimes an ISP will have a Web page that is found by directing your browser to its domain name. So I try out http://ifi.foobar.no. It doesn't work, so I try http://www.ifi.foobar.no. I get the home page for the University of Oslo Institutt for Informatikk. The Informatikk division has strengths in computer science and image processing. Now wonder people with ifi.foobar.no get to use SGI computers.

Next I check out www.foobar.no and learn the University of Oslo has some 39,000 students. No wonder we find so many Internet host computers under the ifi.foobar.no domain!

But let's get back to this header. The next line is pretty simple, just the date:

Date: Fri, 11 Apr 1997 18:09:53 GMT

But now comes the most fascinating line of all in the header, the message ID:

Message-Id: 199704111809.13156.gyllir@ifi.foobar.no

The message ID is the key to tracking down forged email. Avoiding the creation of a valid message ID is the key to using email for criminal purposes. Computer criminals go to a great deal of effort to find Internet hosts on which to forge email that will leave no trace of their activities through these message IDs.

The first part of this ID is the date and time. 199704111809 means 1997, April 11, 18:08 (or 6:08 PM). Some message IDs also include the time in seconds. Others may leave out the "19" from the year. The 13156 is a number identifying who wrote the email, and gyllir@ifi.foobar.no refers to the computer, gyllir within the domain ifi.foobar.no, on which this record is stored.

Where on this computer are the records of the identities of senders of email stored? Now Unix has many variants, so I'm not going to promise these records will be in a file of the same name in every Unix box. But often they will be in either the syslog files or usr/spool/mqueue. Some sysadmins will archive the message IDs in case they need to find out who may have been abusing their email system. But the default setting for some systems, for example those using sendmail, is to not archive. Unfortunately, an Internet host that doesn't archive these message IDs is creating a potential haven for email criminals.

Now we will leave the University of Norway and move on to a header that hides a surprise.

Received: from NIH2WAAF (mail6.foo1.csi.com [149.xxx.183.75]) by
Fubarino.com (8.8.3/8.6.9) with ESMTP id XAA20854 for
<galfina@Fubarino.com>; Sun, 27 Apr 1997 23:07:01 GMT
Received: from CISPPP - 199.xxx.193.176 by csi.com with Microsoft SMTPSVC; Sun, 27 Apr 1997 22:53:36 -0400
Message-Id: <2.2.16.19970428082132.2cdf544e@fubar.com>
X-Sender: cmeinel@fubar.com
X-Mailer: Windows Eudora Pro Version 2.2 (16)
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: galfina@Fubarino.com
From: "Carolyn P. Meinel" <>
Subject: Sample header
Date: 27 Apr 1997 22:53:37 -0400

Let's look at the first line:

Received: from NIH2WAAF (mail6.foo1.csi.com [149.xxx.183.75]) by Fubarino.com (8.8.3/8.6.9) with ESMTP id XAA20854 for <galfina@Fubarino.com>; Sun, 27 Apr 1997 23:07:01 GMT

This first line tells us that it was received by the email account "galfina@Fubarino.com". That's the "for <galfina@Fubarino.com>" part. The Internet host computer that sent the email to galfina was mail6.foo1.csi.com [149.xxx.183.75]. This computer name is given first in a form easily (ha, hah!) read by humans followed by the version of its name that a computer can more easily translate into the 0's and 1's that computers understand. "Galfina" is my user name. I chose it in order to irritate G.A.L.F. (Gray Areas Liberation Front).

"Fubarino.com (8.8.3/8.6.9)" is the name of the computer that received the email for my galfina account. But notice it is a very partial computer name. All we get is a domain name and not the name of the computer from which I download my email. We can guess that Fubarino.com is not the full name because Fubarino is a big enough ISP to have several computers on a LAN to serve all its users.

**************************************************
Evil genius tip: Want to find out the names of some of the computers on your ISP's LAN? Commands that can dredge some of them up include the Unix commands traceroute, dig, and who. For example, I explored the Fubarino.com LAN and found free.Fubarino.com (from command "dig Fubarino.com"); and then dialin.Fubarino.com and milnet.Fubarino.com (from "who" given while logged in my galfina account) Then using the numerical addresses given from the dig command with these names of Fubarino.com computers I then was able, by checking nearby numbers, to find a whole bunch more names of Fubarino.com computers.
**************************************************

The number after Fubarino.com is not a numerical IP address. It is the designation of the version of the mail program it runs. We can guess from these numbers 8.8.3/8.6.9 that it refers to the Sendmail program. But just to make sure, we try the command "telnet Fubarino.com 25." This gives us the answer:

220 Fubarino.com ESMTP Sendmail 8.8.3/8.6.9 ready at Mon, 28 Apr 1997 09:55:58 GMT

So from this we know Fubarino.com is running the Sendmail program.

**************************************************
Evil genius tip: Sendmail is notorious for flaws that you can use to gain root access to a computer. So even though Fubarino.com is using a version of sendmail that has been fixed from its most recently publicized security holes, if you are patient a new exploit will almost certainly come out within the next few months. The cure for this problem may possibly be to run qmail, which so far hasn't had embarrassing problems.
**************************************************

OK, now let's look at the next "received" line in that header:

Received: from CISPPP - 199.xxx.193.176 by csi.com with Microsoft SMTPSVC; Sun, 27 Apr 1997 22:53:36 -0400

CISPPP stands for Compuserve Information Services point to point protocol (PPP) connection. This means that the mail was sent from a PPP connection I set up through Compuserve. We also see that Compuserve uses the Microsoft SMTPSVC mail program. However, we see from the rest of the header that the sender (me) didn't use the standard Compuserve mail interface:

Message-Id: 2.2.16.19970428082132.2cdf544e@fubaretta.com

The number 2.2.16. was inserted by Eudora, and means I am using Eudora Pro 2.2, 16-bit version. The 19970428082132 means the time I sent the email, in order of year (1997), month (04), day (28) and time (08:31:32). The portion of the message ID "2cdf544e@fubaretta.com" is the most important part. That is provided by the Internet host where a record of my use of fubaretta's mail server has been stored.

Did you notice this message ID was not stored with Compuserve, but rather with fubaretta.com? This is, first of all, because the message ID is created with the POP server that I specified with Eudora. Since Compuserve does not yet offer POP servers, I can only use Eudora to send email over a Compuserve connection but not to receive Compuserve email. So, heck, I can specify an arbitrary POP server when I send email over Compuserve from Eudora. I picked the Fubaretta ISP. So there!

If I were to have done something bad news with that email such as spamming, extortion or email bombing, the sysadmin at fubaretta.com would look up that message ID and find information tying that email to my Compuserve account. That assumes, of course, that fubaretta.com is archiving message IDs.

So when you read this part of the header you might think that the computer where I pick up my email is with the Fubaretta.com ISP. But all this really means is that I specified to Eudora that I was using a mail account at Fubar. But if I had put a different account name there, then I would have generated a different message ID. Did I need to have an account at Fubaretta? No. The mail server did not ask for a password. In fact, I don't have an account at Fubaretta. The rest of the header is information provided by Eudora:

X-Sender: cmeinel@fubar.com
X-Mailer: Windows Eudora Pro Version 2.2 (16)
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"

The "X-Mailer" information tells you I was using the 16 bit version of Windows Eudora Pro Version 2.2. Some people have asked me why I don't use the 32 bit version (which runs on Win 95) instead of the 16 bit version. Answer: better error handling! That's the same reason I don't normally use Pegasus. Also, Eudora lets me get away with stuph:) Mime (Multipurpose Internet Mail Extensions)is a protocol to view email. Those of you who got lots of garbage when I sent out GTMHH and Digest can blame it on Mime. If your email program doesn't use Mime, you get lots of stuff like "=92" instead of what I tried to send. But this time I turned off the "printed quotable" feature in Eudora. So this time I hope I sent all you guys plain, friendly ASCII. Please email me if what you got was still messed up, OK? The character set "us-ascii" tells us what character set this email will use. Some email uses ISO ascii instead, generally if it originates outside the US.

Now let's look at a slightly more exciting header. In fact, this is a genuine muhahaha header. Remember that war I declared on Web sites that provide downloads of email bombing programs? You know, those Windows 95 for lusers programs that run from a few mouse clicks? Here's a header that reveals my tiny contribution toward making life unpleasant for the ISPs that distribute these programs. It's from the Happy Hacker Digest, April 12, 1997, from a copy that reached a test email address I had on the list:

Received: by o200.fooway.net (950413.SGI.8.6.12/951211.SGI)for techbr@fooway.net id MAA07059; Mon, 14 Apr 1997 12:05:25 -0400
Date: Mon, 14 Apr 1997 12:05:22 -0400
Received: from mocha.icefubarnet.com by o200.fooway.net via ESMTP (950413.SGI.8.6.12/951211.SGI) for <pettit@cmeinel.com> id MAA06380; Mon, 14 Apr 1997 12:05:20 -0400
Received: from cmeinel (hd14-211.foo.compuserve.com [206.xxx.205.211]) by mocha.icefubarnet.com (Netscape Mail Server v2.01) with SMTP id AAP3428; Mon, 14 Apr 1997 08:51:02 -0700
Message-Id: <2.2.16.19970414100122.4387d20a@mail.fooway.net>
X-Sender: techbr@mail.fooway.net (Unverified)
X-Mailer: Windows Eudora Pro Version 2.2 (16)
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
To: (Recipient list suppressed)
From: "Carolyn P. Meinel" <>
Subject: Happy Hacker Digest April 12, 1997

Now let's examine the first field:

Received: by o200.fooway.net (950413.SGI.8.6.12/951211.SGI)for techbr@fooway.net id MAA07059; Mon, 14 Apr 1997 12:05:25 -0400
Date: Mon, 14 Apr 1997 12:05:22 -0400

We already looked at this computer o200.fooway.net above. But, heck, let's probe a little more deeply. Since I suspect this is a POP server, I'm going to telnet to port 110, which is normally the POP server port.

> telnet o200.fooway.net 110
Trying 207.xxx.192.57...
Connected to o200.fooway.net.
Escape character is '^]'.
+OK QUALCOMM Pop server derived from UCB (version 2.1.4-R3) at mail starting.

Now we know more about Fooway Technology's POP server. If you have ever run one of those hacker "strobe" type programs that tell you what programs are running on each port of a computer, there is really no big deal to it. They just automate the process that we are doing here by hand. But in my humble opinion you will learn much more by strobing ports by hand the same way I am doing here. Now we could do lots more strobing, but I'm getting bored. So we check out the second field in this header:

Date: Mon, 14 Apr 1997 12:05:22 -0400

That -0400 is a time correction. But to what is it correcting? Let's see the next field in the header:

Received: from mocha.icefubarnet.com by o200.fooway.net via ESMTP (950413.SGI.8.6.12/951211.SGI) for <> id MAA06380; Mon, 14 Apr 1997 12:05:20 -0400

Hmmm, why is mocha.icefubarnet.com in the header? If this header isn't forged, it means this mail server was handling the Happy Hacker Digest mailing. So where is mocha.icefubarnet.com located? A quick use of the whois command tells us:

> whois icefubarnet.com
ICEFUBARNET INTERNET, INC (ICEFUBARNET-DOM)
2178 Fooway
North Bar, Oregon 97xxx
USA

Now this is located four time zones earlier than the computer o200.fooway.net. So this explains the time correction notation of -0400.

Next field on the header tells us:

Received: from cmeinel (hd14-211.foo.compuserve.com [206.xxx.205.211]) by mocha.icefubarnet.com (Netscape Mail Server v2.01) with SMTP id AAP3428; Mon, 14 Apr 1997 08:51:02 -0700

This tells us that the Happy Hacker Digest was delivered to the mail server (SMPT stands for simple mail transport protocol) at mocha.icefubarnet.com by Compuserve. But, and this is very important to observe, once again I did not use the Compuserve mail system. This merely represents a PPP session I set up with Compuserve. How can you tell? Playing with nslookup shows that the numerical representation of my Compuserve connection isn't an Internet host. But you can't learn much more easily because Compuserve has great security -- one reason I use it. But take my word for it, this is another way to see a Compuserve PPP session in a header.

Now we get to the biggie, the message ID:

Message-Id: 2.2.16.19970414100122.4387d20a@mail.fooway.net

Whoa, how come that ID is at the computer mail.fooway.net? It's pretty simple. In Eudora I specified my POP server as mail.fooway.net. But if you were to do a little stobing, you would discover that while fooway.net has a POP server, it doesn't have an SMPT or ESMPT server. You can get mail from Fooway, but you can't mail stuff out from Fooway. But the marvelous workings of the Internet combined with the naivete of the Eudora Pro 2.2 program sent my message ID off to mail.fooway.net anyhow.

On the message ID, the "2.2.16" was inserted by Eudora. That signifies it is the 2.2 version for a 16 bit operating system. The remaining fields of the header were all inserted by Eudora:

X-Sender: techbr@mail.fooway.net (Unverified)
X-Mailer: Windows Eudora Pro Version 2.2 (16)
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
To: (Recipient list suppressed)
From: "Carolyn P. Meinel" <>
Subject: Happy Hacker Digest April 12, 1997

Notice Eudora does let us know that techbr@mail.fooway.net is unverified as sender. And in fact, it definitely is not the sender. This is a very important fact. The message ID of an email is not necessarily stored with the computer that sent it out.

So how was I able to use Icefubarnet Internet's mail server to send out the Happy Hacker Digest? Fortunately Eudora's naivete makes it easy for me to use any mail server that has an open SMTP or ESMTP port. You may be surprised to discover that there are uncountable Internet mail servers that you may easily commandeer to send out your email -- if you have the right program -- or if you know how to telnet to port 25 (which runs using the SMTP or ESMTP protocols) and give the commands to send email yourself.

Why did I use Icefubarnet? Because at the time it was hosting an ftp site that was being used to download email bomber programs (http://www.icefubarnet.com/~astorm/uy4beta1.zip). Last time I checked the owner of the account from which he was offering this ugly stuff was unhappy because Icefubarnet Internet had made him take it down.

But -- back to how to commandeer mail servers while sending your message Ids elsewhere. In Eudora, just specify your victim mail server under the hosts section of the options menu (under tools). Then specify the computer to which you want to send your message ID under "POP Server." But if you try any of this monkey business with Pegasus, it gives a nasty error message accusing you of trying to forge email. Of course you can always commandeer mail servers by writing your own program to commander mail servers. But that will be covered in the upcoming GTMHH on shell programming.

*********************************************
Newbie note: Shell programming? What the heck izzat? It means writing a program that uses a sequence of commands available to you in your Unix shell. If you want to be a real hacker, you *must* learn Unix! If you are serious about continuing to study these GTMHHs, you *must* either get a shell account or install some form of Unix on your home computer. You may find places where you can sign up for shell accounts through http://www.celestin.com/pocia/. Or email haxorshell@cmeinel.com for information on how to sign up with a shell account that is friendly to hackers and that you may securely telnet into from your local ISP PPP dialup.
*********************************************

Happy Hacking, and be good!
_________________________________________________________
Want to see back issues of Guide to (mostly) Harmless Hacking? See either
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http://www.silitoad.org
http://base.kinetik.org
http://www.anet-chi.com/~dsweir
http://www.tacd.com/zines/gtmhh/
http://ra.nilenet.com/~mjl/hacks/codez.htm
http://www.ilf.net/brotherhood/index2.html
http://www.magnum44.com/orion/entry.htm
http://www.geocities.com/NapaValley/1613/main.html

Want to share some kewl stuph with the Happy Hacker list? Correct mistakes? To send me confidential email (please, no discussions of illegal activities) use and be sure to state in your message that you want me to keep this confidential. If you wish your message posted anonymously, please say so! Direct flames to dev/null@cmeinel.com. Happy hacking! © 1997 Carolyn P. Meinel. You may forward or post this GUIDE TO (mostly) HARMLESS HACKING on your Web site as long as you leave this notice at the end.


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