Zen and the Art of Internet | Page 9

addresses).
The speed of the transfer depends on the speed of the underlying link. A site that has a 9600bps SLIP connection will not get the same throughput as a system with a 56k leased line (The Physical Connection, for more on what kinds of connections can exist in a network). Also, the traffic of all other users on that link will affect performance. If there are thirty people all FTPing from one site simultaneously, the load on the system (in addition to the network connection) will degrade the overall throughput of the transfer.
FTP Etiquette
Lest we forget, the Internet is there for people to do work. People using the network and the systems on it are doing so for a purpose, whether it be research, development, whatever. Any heavy activity takes away from the overall performance of the network as a whole.
The effects of an FTP connection on a site and its link can vary; the general rule of thumb is that any extra traffic created detracts from the ability of that site's users to perform their tasks. To help be considerate of this, it's highly recommended that FTP sessions be held only after normal business hours for that site, preferably late at night. The possible effects of a large transfer will be less destructive at 2 a.m. than 2 p.m. Also, remember that if it's past dinner time in Maine, it's still early afternoon in California---think in terms of the current time at the site that's being visited, not of local time.
Basic Commands
While there have been many extensions to the various FTP clients out there, there is a de facto ``standard'' set that everyone expects to work. For more specific information, read the manual for your specific FTP program. This section will only skim the bare minimum of commands needed to operate an FTP session.
Creating the Connection
The actual command to use FTP will vary among operating systems; for the sake of clarity, we'll use FTP here, since it's the most general form.
There are two ways to connect to a system---using its hostname or its Internet number. Using the hostname is usually preferred. However, some sites aren't able to resolve hostnames properly, and have no alternative. We'll assume you're able to use hostnames for simplicity's sake. The form is
ftp somewhere.domain
Domains for help with reading and using domain names (in the example below, somewhere.domain is ftp.uu.net).
You must first know the name of the system you want to connect to. We'll use ftp.uu.net as an example. On your system, type:
ftp ftp.uu.net
(the actual syntax will vary depending on the type of system the connection's being made from). It will pause momentarily then respond with the message
Connected to ftp.uu.net.
and an initial prompt will appear:
220 uunet FTP server (Version 5.100 Mon Feb 11 17:13:28 EST 1991) ready. Name (ftp.uu.net:jm):
to which you should respond with anonymous:
220 uunet FTP server (Version 5.100 Mon Feb 11 17:13:28 EST 1991) ready. Name (ftp.uu.net:jm): anonymous
The system will then prompt you for a password; as noted previously, a good response is your email address:
331 Guest login ok, send ident as password. Password: [email protected] 230 Guest login ok, access restrictions apply. ftp>
The password itself will not echo. This is to protect a user's security when he or she is using a real account to FTP files between machines. Once you reach the ftp> prompt, you know you're logged in and ready to go.
Notice the ftp.uu.net:joe in the Name: prompt? That's another clue that anonymous FTP is special: FTP expects a normal user accounts to be used for transfers.
dir At the ftp> prompt, you can type a number of commands to perform various functions. One example is dir---it will list the files in the current directory. Continuing the example from above:
ftp> dir
200 PORT command successful. 150 Opening ASCII mode data connection for /bin/ls. total 3116 drwxr-xr-x 2 7 21 512 Nov 21 1988 .forward -rw-rw-r-- 1 7 11 0 Jun 23 1988 .hushlogin drwxrwxr-x 2 0 21 512 Jun 4 1990 Census drwxrwxr-x 2 0 120 512 Jan 8 09:36 ClariNet ... etc etc ... -rw-rw-r-- 1 7 14 42390 May 20 02:24 newthisweek.Z ... etc etc ... -rw-rw-r-- 1 7 14 2018887 May 21 01:01 uumap.tar.Z drwxrwxr-x 2 7 6 1024 May 11 10:58 uunet-info
226 Transfer complete. 5414 bytes received in 1.1 seconds (4.9 Kbytes/s) ftp>
The file newthisweek.Z was specifically included because we'll be using it later. Just for general information, it happens to be a listing of all of the files added to UUNET's archives during the past week.
The directory shown is on a machine running the Unix operating system---the dir command will produce different results on other operating systems (e.g. TOPS, VMS, et al.). Learning to recognize different formats will take some time. After a few weeks of traversing the Internet, it proves easier to see, for example, how large a