The Internet

Some Background

The Internet is a collective term describing a number of networks all using the protocol known as TCP/IP (Transmission Control Protocol/ Internet Protocol). A more accurate name for this network is the ARPA Internet, since it had its origins in the Department of Defense's Advanced Research Projects Agency in the early 1970s. Today, various networks including ARPA comprise the Defense Data Network; the DDN and others, including Milnet, make up the ARPA Internet. All of Office of Information Technology' computers are connected to the Internet, as are many other systems on campus. These computers are assigned an Internet address (in reality a series of numbers---UMBC machine addresses begin with 130.85), but are referred to by host name and domain, following a specified hierarchical format. For example, the Unix machine UMBC7 is addressed as UMBC7.UMBC.EDU, where UMBC.EDU constitutes the domain. To denote a given user of a system, the prescribed form is username@host.domain, as in JONES@UMBC7.EDU. Among the many other frequently used Internet locations at UMBC are nodes UMBC2 and UMBC8. A trailing EDU in an Internet host name indicates that the site is an educational institution; COM refers to some type of commercial establishment, GOV and MIL denote U.S. government and military establishments, etc. Domain names ending in designations such as NL, UK, NO and CA refer to countries outside the United States; in fact, every country has this type of unique identifier. Most Internet sites are relatively easy to identify assuming you understand the basic naming conventions. However, some do have complex sub-domain identifiers which aid in routing; occasionally you may need to ask for help from Office of Information Technology, especially when your message must pass through a special "gateway" machine before it can reach its destination. Ethernet connections are what makes communications among campus computers possible, and also allow long-distance accessibility via the Internet. A dedicated T1 link to College Park accomplishes this; College Park is linked to other systems and so forth. The benefits of Internet access are many: transfer of files, electronic mail, use of various network features such as file and list servers, and remote logins to other systems.

World Wide Web

There is an enormous amount of information to which Internet users have access---file servers which maintain archives on a wide range of subjects, list servers which allow electronic subscriptions, databases for various uses, and so on and on. In fact, there are so many data sources reachable through the Internet that no one individual is knowledgeable about them all, and simply identifying potential sources had become a major problem for those just beginning to explore their options. Many users who had obtained computer accounts largely for Internet access were then dismayed to find that there was no easy method to avail themselves of what the Internet has to offer. A hit-or-miss situation had arisen, with many more misses than hits.

In recent years a number of very promising solutions have emerged- -- archie, a system for searching indexes of files; WAIS, or Wide Area Information Server, which searches indexed databases for articles containing groups of words; and gopher, a menu-based look-up tool. But the World Wide Web has virtually taken over as the Internet resource because of its user-friendly and nearly always graphical presentations. The WWW can be accessed from all OIT computers through a special program called a browser, which actually is the interface between you, the user, and the Web itself. Using your mouse, click twice on the Netscape or Internet Explorer browser. After an hourglass figure indicates that the program is being located, UMBC's homepage screen will open automatically. You'll also see the Netscape program format, with headers named File, Edit, Bookmarks, and so on, with icons or symbolic depictions of many program functions, with a series of "buttons" offering information such as What's New and What's Cool, with a Help pull-down menu in the far upper right, and with a scroll bar running down the right side of the screen. You'll also see a large "N" on the righthand side.

One of the nicest features about using the World Wide Web to traverse the Internet is that there is far more than one way of accomplishing the same thing. Many paths will give the same result, so when you are comfortable with a particular style, you may want to stick with it. On the other hand, you also may want to experiment. The Web is made even more versatile because it uses built-in HyperText links to other information you may come across while searching for something quite different. This concept works much as the human mind does. While paging through one topic, you may see a reference to something related but veering off in another direction. You might choose to follow this out, abandoning your earlier search, or you might discover that it is not quite what you'd hoped, so you simply step back to the first topic. You can tell where these links exist when a word or phrase is either highlighted or underlined.

Take a good look at UMBC's homepage. Use your mouse and the scroll bar to follow the file to the end. You may see something highlighted or underlined that you want to investigate immediately. If so, use the mouse pointer to move to that subject, and then click. Within a few seconds a file based on that subject will open. Should you want to go back to the homepage, click on Netscape's Back function. If you have gone further afield, Home is the function to use. You may decide to try a net search. If so, click on this feature to see an array of search engines---mechanisms which scan files they are aware of to find the subject you enter. Choose one, click in its "search string" box to position the cursor, and type in your subject. Then click on "search." Most search engines offer hints to allow you to best define your subject matter. Once the search has taken place, you'll see a listing of various locations of projects and files. Choose one. If it proves interesting, you might want to print it by pulling down the File menu to the Print function. If you want to save it for future reference, use Bookmarks. Look at the other features as well. You can save a history of where you've been during this session and then go back to it later.

It is important to note that all files the WWW uses are identified by a URL, or Universal Resource Locator. The URL for UMBC's homepage is http://www.umbc.edu/. In reading electronic news you'll see many references to URLs; some you'll want to jot down so you can Open them in Netscape. Please also take a look at all the UMBC-oriented information provided on the Web. Newsletters, how-to's, schedules, documentation---they're all there.

When you've finished with Netscape for the time being, exit by pulling down either the File menu or the overall program menu to the left and above File. If at any point you are not sure how to proceed, try the Help function. If you are a student, you may also get help from the lab consultant. Faculty and staff members may call OIT' Help Desk at ext. 3838.

Reading Usenet News from Netscape

When Netscape is open you will see that one of its "buttons" is called Newsgroups. This is probably the simplest way to access Usenet News (in reality a type of computer bulletin board), although others are referenced below. (As new versions of Netscape are released, the format and presentation of news tends to differ, but with practice you will see the similarities and thus become comfortable with news from Netscape regardless of presentation.)

Note that you are automatically subscribed to a few newsgroups, especially those helpful to beginners. The screen offers access to directions for unsubscribing, for subscribing to others, for viewing listings of newsgroups so that you can select those of interest, and so on. A special file called newsrc keeps track of your subscribed groups, and within them, which postings are still unread. You can use "buttons" to catch up (mark an entire group as read) and to execute other handy functions. When you have used your mouse to select a newsgroup to read, you will see a listing of article titles. Click on those of potential interest, and catch up when you have finished so as to avoid seeing the unwanted listings again. You can also reply to postings, post your own articles, save articles of particular interest, and execute other useful features as well. Although it is possible to read news via various newsreaders, it is best to select one reader and use that consistently, at least for the present. This will obviate transferring Unix .newsrc files and making other adjustments.

Accessing the Web Without a Graphical Interface

It is far preferable to use WWW resources from an Ethernet-connected microcomputer or workstation, but this may not always be possible. If you are on campus, chances are good that you have the needed connections. However, if you are using a terminal or a terminal emulator, such as when you are dialing up the system (but see below on PPP), you are limited to the functionality of a character cell terminal, which cannot handle graphics applications. Nevertheless, Web information is still available to you, although in a less attractive form, via the program lynx.

Type lynx at the system prompt. Your screen will display an all-text version of the campus homepage, together with instructions for using the program.

Instead of using a mouse to move through the Web, you will type commands and press arrow keys, as explained at the bottom of your screen. Press <RETURN> when an item of interest is highlighted. Extensive help is available. Note that news-reading via lynx is possible but quite cumbersome, and thus is not recommended.

The Web and PPP

If you are dialing up and have installed PPP on your microcomputer, you will be emulating not a terminal, but another Ethernet-connected node, even though the physical connection is a telephone line and not Ethernet wiring. In this case, graphical presentations are possible just as if you were on campus. Open your Netscape browser and proceed as described above. Note, however, that PPP requires a high-speed modem with advanced features. If you are unsure what your modem can do, or if you have other questions, ask the lab consultant or call the Faculty/Staff Help Desk at ext. 3838.

Internet Features Other Than the World Wide Web

Remote Logins (Telnet)

Make sure you know the complete Internet address of the system you are contacting, and remember that you will need a valid account on that node as well. You may connect to any computer at UMBC on which you have an account from the dial-up modems' Annex: or Ascend%: prompts through telnet, as in

annex: telnet umbc7

The UMBC.EDU part of the address is not required here because it is the default if nothing else is entered. If, however, some other location appears after the node name, as in GALAXY.CS.UMBC.EDU, be sure to type it in:

annex: telnet galaxy.cs

The only locations to which you can telnet from UMBC's answering modems' prompts are UMBC computers if you are dialing up at 14.4 or 28.8 Kbaud. If using a lower speed connection you may reach any computer within the UM System. No non-UM machines are accessible at any speed from these modems; thus, to reach any non-UMBC location where you may have an account you must first log in to a UMBC machine. Then you may issue the telnet command from the system prompt. Enter telnet and press <RETURN>. The telnet> prompt will be displayed. Help is available by typing a question mark. Enter the command open followed by the full Internet address of the computer you are accessing. This will start your telnet session.

telnet> open george.washington.edu

Once the connection is made you will be prompted for your username and password on the remote system and then can proceed with your session. Should you prefer, you may invoke telnet and open your connection with just one command---enter telnet GEORGE.WASHINGTON.EDU at the system prompt.

Internet File Transfers

A highly useful feature common to Internet nodes is ftp, or File Transfer Protocol. This is a utility program specifically designed to move files to and from different computer systems. You cannot, however, use ftp as a substitute for electronic mail, since you must first have write access to the remote node before you can send a file there.

Assuming you wanted to use ftp to transfer a file between node UMBC7 and the VMS system UMBC2, enter

ftp UMBC2.UMBC.EDU

on the Unix command line. You will be prompted for login, after which the prompt ftp> will be displayed. It is also possible to enter simply ftp and then open a connection, as can be done from inside Unix with the Bcommand.

Extensive help is available by typing helpor entering a question mark at the utility prompt. Fundamentally, though, you will either be getting or putting files--- get followed by a file name will retrieve the file from UMBC2 and store it on the Unix machine, while put will copy a file to UMBC2. Binary transfers are supported through the binary command---enter this command to put ftp in binary mode before attempting to transfer any binary files.

Very often ftp is used to retrieve files which have been given public access file protection. This is usually accomplished by anonymous login. (Note, however, that the procedure is executed for you automatically, and even the existence and location of files is determined automatically, when you use the World Wide Web, as described earlier in this section.) Under traditional anonymous ftp, when prompted for your username, respond anonymous. Some systems allow you to enter guest as a password, others ask for your real name or your network address. In any event, once you are logged in, use ls or dir to find out what files are available in the current directory and cd to reset the default directory.

When you have completed your transfers, enter quit. On some systems this command is bye. Use the help facility if you are unsure.

Ftp is most useful as a companion to telnet, where you have access to both systems and want a convenient way to store files on each. Although you cannot use it to send files to someone else, some installations do allow you to post files for general consumption. And since you are given only restricted access to the remote system, you cannot execute any system- level commands or perform other actions allowed by telnet.

The following is a sample of a brief ftp session:

ftp umbc2.umbc.edu
Connected to umbc2.umbc.edu
220 UMBC2.UMBC.EDU MultiNet Server Process 3.2(14) at Mon 2-Aug-96 11:10 AM
331 User name (smith) ok. Password, please
Password:
User SMITH logged into FACULTY:[SMITH] at Mon 2-Aug-96 11:10 job 286c.
Remote system type is VMS.
ftp> ls
200 PORT command ok
File transfer started correctly
joe.mem
time.com
temp.out
226 File transfer completed ok
159 bytes received in 0.013 seconds (0.21 Kbytes/s)
ftp> get joe.mem
200 PORT command ok
125 File transfer started correctly
226 File transfer completed ok
local: joe.mem remote: joe.mem
984 bytes received on 0.0039 seconds (2.5e+02 Kbytes/s)
ftp> quit
221 Goodbye

Users should note that UMBC maintains its own ftp site, from which a great deal of useful software can be copied. To reach it, ftp to ftp.umbc.edu, and log in as anonymous. Give your Internet address as your password. A directory listing will show public and "mirrors" headings which you can select to see what may be available. It's a good idea to explore this site on general principles, even if you are not seeking any specific software, as you may find something of interest and will be familiar with this handy resource for future reference.

Sending Mail Over The Internet

Please refer to the section describing pine, the preferred Unix mailer. To send mail to a fellow user of your Unix system, simply respond with his or her username at the mailer's To: prompt.

If you are sending mail to someone at a remote site, at another campus Unix site, or to OIT' VMS machine, make sure you first have that person's correct address so that you can enter it at the pineprompt. For incoming Unix Internet mail, all users of OIT' Unix systems should give their Internet mail addresses in the form <username>@UMBC.EDU, as in JOYCE@UMBC.EDU. Note that a specific node name is not required. This is because a special mail processor at UMBC directs your mail automatically to the node you have specified.

More on Internet Addresses

Doubtlessly the most frequently asked questions, over the Internet and locally, concern the tracking down of usernames and network addresses of researchers and colleagues dispersed around the nation and overseas. By far the simplest way of accomplishing this is to contact the party by traditional means and request the information directly. Many large academic institutions and research sites, including UMBC, have literally hundreds of computer nodes serving as Internet hosts; choosing one by guesswork as the correct address makes little sense. Also, conventions for assigning usernames vary by institution. Under these circumstances the likelihood of success is slim. Netscape, however, does offer various search engines for "people searches," so this is also a good place to try. Another Web source, especially for addresses of users at other UM sites, can be found by tracing "electronic addresses" through "Help" at the UMBC homepage. As is noted above, determining the email address of people here at UMBC has been simplified, at least in part. Those who have accounts on OIT systems can be reached using the domain UMBC.EDU. However, ascertaining the correct username can be tricky. Fortunately, OIT utilizes a special tool, ph, for this purpose. The ph program should be used before you enter a mailer. Then type the results of your search at the mailer's "To:" prompt.

To locate a hypothetical user, Linda Brown, a Physics major whose username is not known, enter:

ph'l* brown'

at the system prompt. (Single quotes are needed when the asterisk is used.)

umbc7> ph 'l* brown' 
---------------------------------------- 
       name: Ms. Laura L. Brown 
   email to: laura@umbc.edu (laura@research.umbc.edu) 
---------------------------------------- 
       name: brown linda 
 curriculum: ba phys 
   email to: lbrown3@umbc.edu (lbrown3@gl.umbc.edu) 
---------------------------------------- 
       name: brown lance 
 curriculum: ba othr 
   email to: lbrown4@umbc.edu (no account registered) 
---------------------------------------- 
       name: Ms. Linda I. Brown 
   email to: librown@umbc.edu (librown@umbc2.umbc.edu) 
----------------------------------------

This output indicates that there is a Linda Brown, majoring in Physics, with the email address lbrown3@gl.umbc.edu, also reachable through the generic UMBC.EDU domain name.

Reading News Outside of Netscape (trn)

Quite a number of programs are available for reading postings to Usenet News, several of which are available on UMBC systems. A "plain vanilla" version is known as rn (for read news), and xrn is handy for those using X-Windows. The mailer pine incorporates a news-reading feature from its Folder Lists screen, though many find this utility rather cumbersome and lacking in "bells and whistles." Of course, the news reader provided by the Web browser Netscape is ideal, but not everyone has access to a graphics environment.

Anyone with a Unix account, however, can access trn, which is an improvement over rn because it groups related articles into "threads"; users therefore can look at discussions of a given topic in one block and skip over uninteresting subjects easily. This is significant because popular newsgroups often receive dozens or even hundreds of contributions a day, only a portion of which are likely to interest a typical reader, even though the group in general is worth perusal. With older programs such as rn, articles are presented strictly in chronological order, a method which necessitates a good deal of plowing through of postings to find articles of note. Users are thus encouraged to try trn, which is documented here. Full details, of course, can be found in the man page for the program. When you invoke trn for the first time, you will find that the system has automatically subscribed you to various local newsgroups likely to be of interest to UMBC users. Among these may be umbc.general, umbc.network, umbc.unix, and umbc.vms.

All of the newsgroups to which a user subscribes or has subscribed are listed in a file in his or her default directory called .newsrc. That file can be examined or edited outside of trn, and its contents can be displayed from inside the program through the L command. All other newsgroup names will be shown via l (note lower case). To subscribe to a particular group that is not listed, issue the command g, followed by the name of the group, as in g sci.med. Note that many courses maintain their own class-based newsgroup; each group's name begins with umbc.course and is followed by the class identifier. Thus there are newsgroups called umbc.course.cs106, umbc.course.cs341, etc. A complete list of subscribed groups will be displayed on your screen each time you enter trn, together with a notation concerning how many articles are currently unread in each. After each group the phrase "read now? [+ynq]" appears as a prompt. Responding + or y, or pressing the space bar or <RETURN> all will have the same effect---the newsgroup will be opened for you to read. An nwill result in a prompt for the next group, and a q will exit you from the program. If you are sure you are not interested in a particular group, enter u for unsubscribe.

If new groups have been created since last you have read news, the name of each will be displayed, together with a "subscribe?" prompt. Your choices are [ynYN]. If you enter Y, you are subscribing to ALL new groups without further prompting; conversely, N means you do not want to subscribe to any new groups or to receive further prompts on this subject. Lower case character responses refer only to the group in question.

Once a newsgroup is open, you will see a listing by "threads" of all unread articles. Each thread is assigned an alphabetic character. The identity of each contributor is shown, as are the subjects of the threads and the number of articles in each. By selecting the alpha character associated with the thread, you are marking those articles for display. Pressing the space bar or entering a carriage return will cause the articles in your selected threads to be presented. Press the space bar to see the remainder of articles longer than one screen. Press n to go on to the next article. You may quit (q) before reading all the articles in a given thread, in which case the thread selector will be displayed again. If you enter a c you are indicating you want to catch up---that is, to mark all remaining articles as read, even if you have not looked at them. If the newsgroup proves to be not to your liking, unsubscribe to it with a u. On any level and at any prompt, an h may be entered for a list of commands available at that level. Since trn has a great many features---far more than can be described here---it is a good idea to use the h feature liberally.

Posting a News Article Outside of Netscape

To post an article, enter the command Pnews at the Unix system prompt. You will be prompted for the group or groups to which your article should be posted. You will then be asked about the distribution of your article. Your choices include:

An example of using distributions properly might be an instance of someone at UMBC trying to sell a used car. It is unlikely that a person in California would be interested in an average used car being sold in Maryland, so the appropriate distribution for that article would be dc, and appropriate newsgroups might be dc.general and misc.forsale. However, if the car being sold were a valuable collector's item, a distribution of usa or na might be appropriate, and appropriate newsgroups might include dc.general, misc.forsale and rec.autos.

After you have selected your distribution, you will be asked for your article subject, and then for the name of a prepared file containing your article. If you have not yet created one press <RETURN> ; your editor will be invoked so that you can compose your article. Exit as usual, and choose send from the menu options.

From within trn, you may use the f or F command to respond to an article after reading it. You will be prompted for distribution, etc., as above.