Internet Draft R. Plzak Document: ARIN G. Malkin Nortel Networks Walter Houser VA March 2002 FYI on Questions and Answers Answers to Commonly asked "Experienced Internet User" Questions Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract This memo provides information to the experienced Internet user that wants to know more. The term "experienced user" is used to differentiate this user from the new users addressed by FYI4. The term experienced is relative. For the purpose of this memo ôexperiencedö is any user who is familiar with the concepts described in FYI 4. The information provided in this memo is what may be described as an upper level or top level description of some of the applications and protocols that are in common use on the Internet today. This memo does not provide precise technical descriptions. For these the reader is referred to the appropriate RFC or other documentation. A conscious effort has been made to keep this memo brief but at the same time provide the depth of information necessary to provide a general understanding of the applications and protocols described. Plzak, Malkin, Houser 1 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 2. Doing Things on the Internet or "How Does It Work?" 2.1. How does email work? Electronic mail is a lot like paper mail (also called snail mail). The chart below summarizes these similarities. Paper Mail Email Addressee To Return Address From Enclosure Attachment Carbon Copy cc After you write your message, your email software puts all this into an envelop with addressing information that repeats some of these same elements on the envelop. It then looks for a computer with a mail service called Simple Mail Transfer Protocol (SMTP), which serves like a mailbox outside your local post office. The SMTP service passes your message to nearby SMTP computers (or servers) who know or can find the destination for your addressee. If any of these SMTP servers have trouble delivering your message, you will receive a delivery notice explaining the nature of the problem. Because email can be misunderstood or abused, users should be familiar with email netiquette. For more information see Netiquette Guidelines [FYI 28, RFC 1855]. 2.2. What is a Mailing List? A mailing list is a collection of email addresses of people interested in a specific topic such as hobbies, product updates, work projects, and electronic newsletters. Mail lists usually have a set of rules pertaining to how the list is to be used and what type of information is considered proper for the list. This is referred to as an Acceptable Use Policy (AUP). There are generally two types of lists û announcement and discussion. Announcement lists go one way from the list owner/manager to the subscribers. This type of list is generally used by an organization to alert its subscribers to information that is of particular interest to the subscribers. The subscribers cannot send information to other subscribers on the list via the list. Discussion lists are used by subscribers to discuss topics of interest to them. By sending a message to the list a subscriber is in effect talking to all of the subscribers. There are two types of discussion lists û moderated and un-moderated. In an moderated list the message sent by a subscriber to the list is reviewed by the list ômoderatorö prior to being sent to all subscribers. In an un- moderated list this review does not take place. A message sent to the list by a subscriber is immediately sent to all subscribers. Plzak, Malkin, Houser Expires September 2002 2 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 2.3. How does the World Wide Web work? Your web browser (Netscape, Internet Explorer, etc.) displays web pages located on various computers operating web servers. These web pages are written in Hypertext Markup Language (HTML) or extensible Markup Language (XML). The web server sends the web pages and images to your PC using the Hypertext Transfer Protocol (HTTP). Your web browser ôrendersö the page, placing images and other page elements in their designated positions in the browser window. As you move your cursor across the page, you should notice the cursor changes shape over what are called ôhyperlinks.ö Typically underlined and in blue, hyperlinks will take you to other web pages, on the same server or on any web server in the world. Pressing the hyperlink tells your browser to contact that destination web server for the next web page. 2.4. What is Instant Messaging? Many Internet service providers offer Instant messaging (IM), a popular tool to keep in touch using the Internet. You announce your presence by entering your IM ôhandleö or nickname into the IM pop-up window. You can use the same window to see if your friends are online. Unlike chat (see below), IM is one-to-one; some chatters will have side conversations using IM. Many of the current IM protocols are not yet standardized so you may not be able to IM with someone on another service provider. 2.5. How do I send a lot of data across the Internet? Although you can send files or documents as attachments using email, most mail services limit the size or number of these attachments. The size of the attachment can be reduced by the use of an application known as a compression program. A compression program can reduce the size of a single attachment or it can be used to combine several files into one attachment. When sending an attachment, users should consider the capability of the intended recipientÆs mail service to accept attachments or the speed at which the recipient is connected to the internet. If the recipient canÆt get the attachment it might as well not be sent. If email wonÆt work for sending the attachment, then the sender should look to using either http or ftp as the means for the intended recipient to get the file. 3. Getting around the Internet 3.1. What is an IP address? An Internet Protocol (IP) address is a binary number that is used to uniquely identify an Internet host. It does not provide Plzak, Malkin, Houser Expires September 2002 3 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 geographical information. There are two versions of IP addresses in use on the Internet today - IPv4 and IPv6. IPv4, the older version, is a 32-bit number. It has been in use for many years but as the Internet grew there arose concerns about there being enough unique addresses to go around so the newer 128-bit IPv6 version was developed. IPv6 is in the early stages of use so the Internet continues to use IPv4 addresses. The 32-bit IPv4 address is divided into 4 bytes. In decimal notation each byte is separated by a dot so that a typical address looks like this: 192.168.202.7. The 128 bits of the IPv6 address are divided into eight (8) groups of 16 bits. The groups are separated by a colon and are written in hexadecimal notation. An IPv6 address looks like this: FEDC:BA98:7654:3210:FEDC:BA98:7654:3210. Thankfully users don't have to remember IP addresses to use the Internet - the Domain Name System (DNS) translates easily remembered names to addresses. 3.2. What is a packet? A "packet" is a unit of information that is transmitted. This piece of information may be transmitted on a local network or across the internet. Different protocols such as IP or TCP have specific formats for a packet and consequently have a specific name for the packet that they use. 3.3. What is a router and what does it do with packets? A router is a special purpose computer that directs packets across the internet. A portion of the packet, called the header, contains information about the packet such as the IP address of the sender and the intended recipient. The router checks this and the other information in the header. If the information is invalid the router discards the packet and sends an error message back to the originator of the packet. If the information is valid the router uses the IP address of the intended recipient and information in its routing table to determine the best possible path or route to the ultimate destination of the packet. A routing table is a listing of the best routes to either the ultimate destination or to a router which is an intermediate point to the destination. The routerÆs routing table is updated continuously because routers share information with each other about the best way to get around the internet. 3.4. What is DNS? DNS is the Domain Name System. The internet uses numbers (IP addresses) to send packets around the internet. However, humans find these numbers awkward and difficult to easily remember. It is much easier for them to remember names. Consequently computers on the internet have names as well as addresses. Applications such as email or web browsers accept names and then use DNS to translate or Plzak, Malkin, Houser Expires September 2002 4 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 resolve a name into the correct IP address so that the packet can be routed. A name consists of several parts or labels that are separated by dots, for example, a.foo.bar. In this case ôaö, ôfooö and ôbarö are labels. Each label cannot exceed 63 characters, the entire name including the dots cannot exceed 255 characters. Another important thing to remember about names is that they can contain only upper or lower case alphabetic letters, numbers or the special characters ô.ö or ô-ô. In the example a.foo.bar, the entire name is called a Fully Qualified Domain Name. The label that is furthest to the left identifies a specific computer or host. The remaining labels identify domains. To the right of the last label there is one more dot which identifies the top most or root domain. Typically a computer known as a name server is associated with each domain to include the root domain. Each of these name servers contains information about its domain in a file that is called a zone file. This information enables a name server to either resolve a name to an IP address or refer it to a zone that can provide more information. 3.5. How does DNS Resolve a Name to an IP Address? When an application such as email attempts to send a packet across the internet it needs to have an IP address. It takes the name of the destination computer and gives it to a special program known as a resolver to make the translation of the name to the address. The resolver first looks locally to see if it has the required information. If it does not, then it sends the query to the root. Beginning at the root, it and each subsequent name server associated with the domains in the FQDN will either provide a referral to the next name server or will provide the desired IP address. Once the IP address has been determined the query stops and the address is provided to the requesting application. 3.6. What is an intranet? An intranet is a collection of networks that may or may not be connected to the Internet. Generally, an intranet is maintained and administered by an organization that may be a commercial firm or a government organization. If the intranet is connected to the Internet it is usually done at selected points that control access from the intranet to the Internet and control access from the Internet to the intranet. Typically, only certain services such as email are permitted to flow across these control points. Plzak, Malkin, Houser Expires September 2002 5 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 3.7. What is Tunneling? Tunneling is the term applied to establishing an end-to-end connection for the purpose of providing protected transfer of information across the Internet. One typical method of doing this is to encrypt packets at the transmission end and decrypt them at the reception end. 4. Security Considerations 4.1 How do I protect my personal information when I surf the Internet? The ubiquitous nature of the Internet has resulted in widespread concern for the loss of personal privacy. Once your privacy is compromised, you cannot get it back. The US Federal Trade Commission has identified four elements of privacy protection. They are notice, consent, access, and security. While these are definitions provided by the US government they pretty much sum up what is required for privacy protection. * Notice. You should always be notified by the requestor of your private information how this information will be used. * Consent. You must consent to it being used. * Access. The only authorized access to your information is for its request use. * Security. The requestor of your information should provide you with an assurance of how the information will be protected from unauthorized individuals and organizations. 4.2 What steps should I take to protect myself when shopping on the Internet? Know the vendor you are dealing with. Only enter credit or debit card information when using a secure connection to the merchant; look for the little padlock at the bottom of your web browser. Know what liability limits are associated with your card. 5. References [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Hambridge, S. "Netiquette Guidelines", RFC 1855, October 1995. Plzak, Malkin, Houser Expires September 2002 6 INTERNET DRAFT FYI Q/A - for New Internet Users March 2002 7. Author's Addresses Raymond Plzak ARIN 4506 Daly Drive, Suite 200 Chantilly, VA 20151 Phone: +1.703.227.9850 Email: plzak@arin.net Gary Malkin Nortel Networks 600 Tech Park Billerica, MA 01621 Phone: +1.978.288.3684 Email: gmalkin@nortelnetworks.com Walter Houser Program Coordination Staff (045APC) Department of Veterans Affairs 810 Vermont Avenue Washington DC 20420 Email: houser.walt@forum.va.gov Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Plzak, Malkin, Houser Expires September 2002 7