Teracom Training Institute Newsletter

NEWSLETTER
MARCH 2008

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In this issue...

Budget Year-End Specials!

- DVD library 40% off

- Telecom 101 textbooks 45% off

- BOTH... DVD library with ten (10) free Telecom 101 textbooks

plus

Tutorial: Authentication, Digital Signatures and Digitally-Signed Email

Nearing year-end? Money left in budgets? Seize the opportunity to benefit from Teracom's world-renowned training.
To make it even easier, we're putting on great specials until March 31.

Funds - in either departmental or project budgets - for training, employee development, productivity enhancement, team building, special projects, furnishings, office supplies and general expenses can all be legitimately used to make this invaluable, productivity-enhancing addition to your group's resources.

Budget Year-End Special #1: Teracom DVD-Video Course Library - 40% off

> free previews

	Teracom's Full DVD Library is an excellent choice for allocating budgeted funds at year-end, and an invaluable addition to your departmental training resources.

	Covering everything from POTS to CDMA, VoIP and MPLS, we • bust the buzzwords, • demystify jargon, • explain technologies, protocols and mainstream solutions, and most importantly: • the underlying ideas and how it all works together... in plain English.

	Establishing this solid knowledge base increases productivity and improves efficiency, eliminating buzzword and bafflegab frustration. Join the thousands of organizations who have have benefited! Many people tell us they wish they'd had this training years ago.

	Until March 31, the library of all nine Teracom DVD-video courses with nine course workbooks, is on sale for $997... a savings of more than 40%.

Order DVD-video product # V540 either online with your credit card, or fax us a PO along with the printed order form, and get this world-renowned training today. Free domestic shipping!

You will receive the full library of NINE two-hour multimedia courses. Compare this $2000 for ONE course elsewhere, and you'll agree this is a very good deal. PLUS, our courses are up-to-date, authoritative, and packed with information. Add to this the high-quality student materials for each course, the exercises and certificate suitable for framing... details previews

Your satisfaction is guaranteed.
If for any reason you are dissatisfied, simply return the DVD courses for a refund. details

Budget Year-End Special #2: Telecom 101, new 3rd edition - $99 each for two or more

	Telecom 101 is the three course workbooks from our acclaimed core training Course 101 Telecom, Datacom and Networking for Non-Engineers combined together into a professionally-bound standard softcover textbook with 400 pages, 177 diagrams and a full index.

	This invaluable reference book and day-to-day handbook covers telecom, datacom and networking from A-Z, organized in logical chapters covering all major topics, and written in our signature "telecom for non-engineers" style.

	This content, tuned and refined over the course of fifteen years, has been taught to thousands of people needing to build a solid, structured understanding of telecom, datacom and networking. A high percentage of seminar attendees specifically praise the course materials on evaluations – now available in textbook format more

	Until March 31, it's on sale for $99 when you buy two or more copies, a savings of more than 40% off the regular price.

Order textbook product # T102, either online with your credit card, or fax us a PO along with the printed order form, and get this world-renowned training today.

Budget Year-End Special #3: BOTH
Order the Full DVD Library and get ten (10) Telecom 101 reference books free

Our best offer yet: get both the DVD library and Telecom 101 reference books!
Order the Full DVD Library at the regular price and we will include a set of ten Telecom 101 reference books, for everyone in your group. This is in addition to the video course workbooks.

Order DVD-video product # V550, either online with your credit card, or fax us a PO along with the printed order form, and get this world-renowned training today.

Cinema-quality video, animated bullets, plenty of crisp graphics, navigation menus and more - Teracom DVDs are private high-quality multimedia lessons from the Director of the Institute! DVDs also mean guaranteed to play, convenient broadband and easy to pass around in your department. They are ideal to watch on your laptop during a flight. Connect to an LCD projector and you've got very high value-added group training for your people.

Satisfaction guaranteed or your money refunded. What have you got to lose? Act now before it's too late.

The fine print
Free shipping applicable to destinations in the US lower 48 states and Canadian 10 provinces. Anywhere else, please contact us for shipping price. Payment or PO must be received by March 31 2008. Cannot be combined with any other offers or discounts. Satisfaction guarantee: if you are dissatisfied with your purchase for any reason, contact us within 30 days of your order date to request a Return Materials Authorization (RMA) number and ship all items back to us prepaid with signature proof of delivery. All items must be unused and in their original packaging. Your purchase price less our shipping and handling cost and a $50 restocking charge will be refunded after the items are inspected. The shipment will be returned to you without further processing if any items are missing or exhibit signs of damage or use. Applicable to products where expressly stated only. Defective items may be exchanged for the same item within one year.

Tutorial: Authentication, Digital Signatures and Digitally-Signed Email

E-mail was one of the first "killer apps" on the Internet, and has been a major contributor to increases in productivity over the past ten years. Of course, along with email came the scourge of spam. Criminals infect computers with trojan horse programs, creating collections of machines they control remotely to send millions of unsolicited offers for fake watches, pirated software, phony medications and ecard invitations to infect your computer.

As spam reaches 30, 40 or even 100 unwanted messages per day on a targeted account, it is becoming essential to automatically separate legitimate messages from spam. One tool available to senders of legitimate emails to aid the recipient in this process is to digitally sign their messages, allowing the recipient to establish a level of comfort that the message actually came from the indicated sender.

This email is digitally signed. Your mail client may indicate that it has verified the signature; for example, yahoo mail displays a key icon and gmail states "signed by" below the the to: and from: information. This verification can be used to raises the confidence level at your end that the message is legitimate.

Digital signatures are implemented with asymmetric encryption. Asymmetric means that there are two keys (binary numbers). What is encrypted using one key can be decrypted with the other... and vice-versa. The most popular method of generating key pairs and using them for encryption and decryption was devised by three fellows named Rivest, Shamir and Adelman and is called RSA.

A standard strategy is to generate a key pair, then make one of the keys visible to the public and keep the other key private.

Digitally signing a message means the sender using their private key to encrypt selected text and attaching that to the message.

To authenticate the message, that is, verify the digital signature, the recipient can get a copy of the purported sender's public key and use that to try to decrypt the selected text attached to the message.

If the decryption using the sender's public key is successful, then the recipient knows that the message was indeed "signed" by the sender (or by someone who stole the sender's private key).

This process is called authentication.

Yahoo developed the Domainkeys strategy, which is implemented for this email:

At the sender, the Secure Hash Algorithm 1 (SHA-1) is used to generate a "hash" or unique binary number representing the email message body and headers such as Message-ID, Received header, the X-Mailer header, Date header, From:, To:, MIME-Version: and Content-Type headers. This hash is then encrypted with the sender's private key using RSA, and the encrypted hash is added as another message header.

At the receiver, it is necessary to get the sender's public key... so how does the receiver get that? The Domain Name System (DNS) is used. Normally, DNS records relate domain names to IP addresses; but it turns out that a DNS record type that allowed free text for comments or domain info was implemented, and this is used to store the domain's public key.

So the receiver examines the domain name of the purported sender, does a DNS lookup to get the domainkeys public key for that domain, and uses it to decrypt the hash contained in the email header. The receiver also computes the hash of the received message and compares the two.

If they are not the same, then the message was not sent by that domain (the From: field is false, for example), or the message was altered, and the receiver would generally put the message in the garbage where it belongs.

If the hash of the message and the hash in the header are the same, then we have a high confidence that domain sent the message. This knowledge might be combined with other knowledge, for example the reputation of the sending domain, and used to decide to place the message in the inbox.

This sending-domain authentication using digital signatures is one tool in the fight against spam. Teracom has implemented it to help ensure that our newsletter goes into your inbox, particularly if you use Yahoo mail. Note that if you want to be absolutely sure these messages go in your inbox, also add "newsletter@teracomtraining.com" to your whitelist / trusted senders / address book... this is the "reputation" part of the previous paragraph.

The Yahoo Domainkeys strategy is being improved and standardized in RFC 4871.

Asymmetric encryption, digital signatures and authentication are covered in:
Teracom DVD-Video Course V5, "Understanding Networking 2", and in
Teracom instructor-led Course 110, "IP Telecommunications".

DNS is covered in
Teracom DVD-Video Course V5, "Understanding Networking 2", and in
Teracom instructor-led Course 101 Telecom, Datacom and Networking for Non-Engineers"

Here are a few links that you may find useful:


Course 101 Core training		Course 110 Core training II		Course 120 Wireless training		Course 130 VoIP training		Course 150 IP Call Center training


		Who should attend
		Six reasons to benefit from Teracom training
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