Go to the previous, next section.
New and interesting ways to use the Internet are being dreamed up every day. As they gain wide-spread use, some methods become near-standard (or actual written standard) tools for Internet users to take advantage of. A few are detailed here; there are undoubtedly others, and new ideas spring up all the time. An active user of the Internet will discover most of the more common ones in time. Usually, these services are free. See section Commercial Services for applications that are commercially available over the Internet.
Usenet is often used to announce a new service or capability on
the Internet. In particular, the groups
comp.protocols.tcp-ip are good places to look. Information
will drift into other areas as word spreads. See section Usenet News for
information on reading news.
On many systems there exists the `finger' command, which yield information about each user that's currently logged in. This command also has extensions for use over the Internet, as well. Under normal circumstances, the command is simply `finger' for a summary of who's logged into the local system, or `finger username' for specific information about a user. It's also possible to go one step further and go onto the network. The general usage is
To see who's currently logged in at Widener University, for instance, use
% finger @cs.widener.edu [cs.widener.edu] Login Name TTY Idle When Where brendan Brendan Kehoe p0 Fri 02:14 tattoo.cs.widene sven Sven Heinicke p1 Fri 04:16 xyplex3.cs.widen
To find out about a certain user, they can be fingered specifically (and need not be logged in):
% finger email@example.com [cs.widener.edu] Login name: bart In real life: Bart Simpson Directory: /home/springfield/bart Shell: /bin/underachiever Affiliation: Brother of Lisa Home System: channel29.fox.org Last login Thu May 23 12:14 (EDT) on ttyp6 from channel29.fox.org. No unread mail Project: To become a "fluff" cartoon character. Plan: Don't have a cow, man.
Please realize that some sites are very
conscious, and need
to restrict the information about their systems and users available to
the outside world. To that end, they often block
requests from outside sites--so don't be surprised if fingering a
computer or a user returns with `Connection refused'.
The `ping' command allows the user to check if another system is currently "up" and running. The general form of the command is `ping system'.(11) For example,
will tell you if the main machine in Widener University's Computer Science lab is currently online (we certainly hope so!).
Many implementations of `ping' also include an option to let you see how fast a link is running (to give you some idea of the load on the network). For example:
% ping -s cs.swarthmore.edu PING cs.swarthmore.edu: 56 data bytes 64 bytes from 188.8.131.52: icmp_seq=0 ttl=251 time=66 ms 64 bytes from 184.108.40.206: icmp_seq=1 ttl=251 time=45 ms 64 bytes from 220.127.116.11: icmp_seq=2 ttl=251 time=46 ms ^C --- cs.swarthmore.edu ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max = 45/52/66 ms
This case tells us that for `cs.swarthmore.edu' it takes about 46 milliseconds for a packet to go from Widener to Swarthmore College and back again. It also gives the average and worst-case speeds, and any packet loss that may have occurred (e.g. because of network congestion).
While `ping' generally doesn't hurt network performance, you shouldn't use it too often--usually once or twice will leave you relatively sure of the other system's state.
Sometimes email is clumsy and difficult to manage when one really needs to have an interactive conversation. The Internet provides for that as well, in the form of talk. Two users can literally see each other type across thousands of miles.
To talk with Bart Simpson at Widener, one would type
which would cause a message similar to the following to be displayed on Bart's terminal:
Message from Talk_Daemon@cs.widener.edu at 21:45 ... talk: connection requested by firstname.lastname@example.org talk: respond with: talk email@example.com
Bart would, presumably, respond by typing `talk firstname.lastname@example.org'.
They could then chat about whatever they wished, with instantaneous
response time, rather than the write-and-wait style of email. To
talk, on many systems one would type
Ctrl-C (hold down
the Control key and press `C'). Check local documentation to be sure.
There are two different versions of talk in common use today. The
first, dubbed "old talk," is supported by a set of Unix systems
(most notably, those currently sold by Sun). The second,
(aka "new talk"), is more of the standard. If, when attempting to
talk with another user, it responds with an error about protocol
families, odds are the incompatibilities between versions of talk is
the culprit. It's up to the system administrators of sites which use
the old talk to install
ntalk for their users.
The main WHOIS database is run at the Network Information Center (NIC). The `whois' command will let you search a database of every registered domain (e.g. `mit.edu') and of registered users. It's primarily used by system postmasters or listowners to find the Points of Contact for a site, to let them know of a problem or contact them for one reason or another. You can also find out their postal address. For example:
% whois mit.edu Massachusetts Institute of Technology (MIT) MIT.EDU 18.104.22.168 Massachusetts Institute of Technology (MIT-DOM) MIT.EDU
Note that there are two entries for `mit.edu'; we'll go for the second.
% whois mit-dom Massachusetts Institute of Technology (MIT-DOM) =>Mailing address Cambridge, MA 02139 Domain Name: MIT.EDU =>Domain name Administrative Contact, Technical Contact, Zone Contact: Schiller, Jeffrey I. (JIS) JIS@MIT.EDU (617) 253-8400 Record last updated on 22-Jun-88. =>Last change made to the record Domain servers in listed order: =>Systems that can tell you the Internet addresses for a site STRAWB.MIT.EDU 22.214.171.124 W20NS.MIT.EDU 126.96.36.199 BITSY.MIT.EDU 188.8.131.52 LITHIUM.LCS.MIT.EDU 184.108.40.206 To see this host record with registered users, repeat the command with a star ('*') before the name; or, use '%' to show JUST the registered users.
Much better! Now this information (sought, possibly, by a system administrator) can be used to find out how to notify MIT of a security issue or problem with connectivity.
Queries can be made for individuals as well; the following would yield an entry for the author:
% whois brendan Kehoe, Brendan (BK59) email@example.com Widener University Department of Computer Science Kirkbride 219 P.O. Box 83 Widener University Chester, PA 19013 (215)/499-4011 Record last updated on 02-May-91.
Included is the author's name, his handle (a unique sequence of letters and numbers), information on how to contact him, and the last time the record was modified in any way.
Anyone can register with the whois database. People who are
administrative or technical contacts for domains are registered
automatically when their domain applications are processed. For
normal users, one must simply fill out a form from the NIC. FTP to
nic.ddn.mil and get the file `netinfo/user-template.txt'.
The completed form should be mailed to `firstname.lastname@example.org'.
Also, many educational sites run WHOIS servers of their own, to offer information about people who may be currently on the staff or attending the institution. To specify a WHOIS server, many implementations include some sort of option or qualifier--in VMS under MultiNet, it's `/HOST', in Unix `-h'. To receive information about using the Stanford server, one might use the command
whois -h stanford.edu help
A large list of systems offering WHOIS services is being maintained by
Matt Power of MIT (
email@example.com). It is available via
anonymous FTP from
sipb.mit.edu, in the directory
`pub/whois'. The file is named `whois-servers.list'.
The systems available include, but are certainly not limited to,
Syracuse University (
syr.edu), New York University
acfcluster.nyu.edu), the University of California at San Diego
ucsd.edu), and Stanford University (
"Fingers were made before forks." Jonathan Swift, Polite Conversation
Go to the previous, next section.