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diff --git a/doc/rfc/rfc1635.txt b/doc/rfc/rfc1635.txt new file mode 100644 index 0000000..c9f131e --- /dev/null +++ b/doc/rfc/rfc1635.txt @@ -0,0 +1,731 @@ + + + + + + +Network Working Group P. Deutsch +Request for Comments: 1635 A. Emtage +FYI: 24 Bunyip +Category: Informational A. Marine + NASA NAIC + May 1994 + + + How to Use Anonymous FTP + +Status of this Memo + + This memo provides information for the Internet community. This memo + does not specify an Internet standard of any kind. Distribution of + this memo is unlimited. + +Abstract + + This document provides information for the novice Internet user about + using the File Transfer Protocol (FTP). It explains what FTP is, + what anonymous FTP is, and what an anonymous FTP archive site is. It + shows a sample anonymous FTP session. It also discusses common ways + files are packaged for efficient storage and transmission. + +Acknowledgements + + This document is the result of work done in the Internet Anonymous + FTP Archives (IAFA) working group of the IETF. Special thanks are + due to Mark Baushke (Cisco), John Curran (BBN), Aydin Edguer (CWRU), + Rafal Maszkowski (Onsala Space Observatory), Marsha Perrott + (PREPnet), Bob Peterson (Texas Instruments), Nathan Torkington + (Victoria University of Wellington), and Stephen Tihor (NYU) for + excellent comments and contributions. + +What is FTP? + + FTP refers to the File Transfer Protocol [1], one of the protocols + within the TCP/IP protocol suite used on the Internet. The File + Transfer Protocol makes it possible to transfer files from one + computer (or host) on the Internet to another. There are many FTP + implementations built on the specification of the FTP protocol. A + user of an FTP program must log in to both hosts in order to transfer + a file from one to the other. + + It is common for a user with files on more than one host to use the + FTP program to transfer files from one host to another. In this + case, the user has an account on both hosts involved, so he has + passwords for both hosts. + + + +IAFA Working Group [Page 1] + +RFC 1635 How To FTP May 1994 + + + However, Internet users may also take advantage of a wealth of + information available from archive sites by using a general purpose + account called "anonymous FTP". + +What is an Archive Site? + + An archive site is a host that acts as a repository of information, + much like a conventional library. Information stored on these + Internet hosts is made available for users to transfer to their local + sites. Users run software to identify this information and transfer + it to their own hosts. Such a transfer is done with a program that + implements the File Transfer Protocol (FTP). + +What is Anonymous FTP? + + Anonymous FTP is a means by which archive sites allow general access + to their archives of information. These sites create a special + account called "anonymous". User "anonymous" has limited access + rights to the archive host, as well as some operating restrictions. + In fact, the only operations allowed are logging in using FTP, + listing the contents of a limited set of directories, and retrieving + files. Some sites limit the contents of a directory listing an + anonymous user can see as well. Note that "anonymous" users are not + usually allowed to transfer files TO the archive site, but can only + retrieve files from such a site. + + Traditionally, this special anonymous user account accepts any string + as a password, although it is common to use either the password + "guest" or one's electronic mail (e-mail) address. Some archive + sites now explicitly ask for the user's e-mail address and will not + allow login with the "guest" password. Providing an e-mail address + is a courtesy that allows archive site operators to get some idea of + who is using their services. + +What Information Do You Need to Know? + + To retrieve a specific file, a user needs to know what host it is on, + and the pathname of the file. A pathname tells the directory (and + possibly subdirectories) that house the file, and the name of the + file. Often discussions of available files will not specifically + say, "This file is available for anonymous FTP from X host with Y + pathname". However, if a file is publicly announced as available and + referred to as something like pub/good-stuff on nisc.sri.com, it is a + good assumption that you can try to transfer it. + + You may also need to know if your machine uses an ASCII, EBCDIC, or + other character set to know how likely a transfer of binary + information will work, or whether such a transfer will require other + + + +IAFA Working Group [Page 2] + +RFC 1635 How To FTP May 1994 + + + keywords, such as is true for TENEX. + + In the general case, you may assume that an ASCII transfer will + always do the right thing for plain text files. However, more and + more information is being stored in various compressed formats (which + are discussed later in this document), so knowing the binary + characteristics of your machine may be important. + +A Sample Session + + To start an FTP session on a UNIX or VMS host, you type "ftp" and the + host name or host IP address of the machine to which you want to + connect. For example, if you wish to access the NASA Network + Applications and Information Center archive site, you would normally + execute one of the following commands at the UNIX prompt: + + + ftp naic.nasa.gov + or + ftp 128.102.128.6 + + Observe that the first form uses the fully-qualified domain name and + the second uses the Internet address for the same host. + + The following is an example of connecting to the naic.nasa.gov host + to retrieve STD 9, RFC 959, "File Transfer Protocol (FTP)" [1]. + + Note several things about the session. + + 1. Every response the FTP program at the archive site gives + is preceded by a number. These numbers are called + Reply Codes and are defined in the FTP specification, + RFC 959. The text that accompanies these reply codes + can vary in different FTP implementations, and usually does. + + Also note that some FTP client implementations (e.g., MVS + systems) may not echo the reply codes or text as + transmitted from the remote host. They may generate their + own status lines or just hide the non-fatal replies + from you. For the purposes of this document, the more + popular UNIX interface to the FTP client will be + presented. + + 2. The password you type is never shown on your screen. + + 3. It is possible to "browse" in archives, but most often users + already know the pathname of the file they want. The pathname + for RFC 959 on this host is files/rfc/rfc959.txt. In the + + + +IAFA Working Group [Page 3] + +RFC 1635 How To FTP May 1994 + + + example, we first connect to the 'files/rfc' directory (cd + files/rfc), then get the specific file we know we want. If you + do not know the name of the file you want, a file called README + or something similar (00README.1ST, AAREAD.ME, INDEX, etc.) is + probably the one to retrieve first. + + atlas.arc.nasa.gov% ftp naic.nasa.gov + Connected to naic.nasa.gov. + 220 naic.nasa.gov FTP server (Wed May 4 12:15:15 PDT 1994) ready. + Name (naic.nasa.gov:amarine): anonymous + 331 Guest login ok, send your complete e-mail address as password. + Password: + 230----------------------------------------------------------------- + 230-Welcome to the NASA Network Applications and Info Center Archive + 230- + 230- Access to NAIC's online services is also available through: + 230- + 230- Gopher - naic.nasa.gov (port 70) + 230- World-Wide-Web - http://naic.nasa.gov/naic/naic-home.html + 230- + 230- If you experience any problems please send email to + 230- + 230- naic@nasa.gov + 230- + 230- or call +1 (800) 858-9947 + 230----------------------------------------------------------------- + 230- + 230-Please read the file README + 230- it was last modified on Fri Dec 10 13:06:33 1993 - 165 days ago + 230 Guest login ok, access restrictions apply. + ftp> cd files/rfc + 250-Please read the file README.rfc + 250- it was last modified on Fri Jul 30 16:47:29 1993 - 298 days ago + 250 CWD command successful. + ftp> get rfc959.txt + 200 PORT command successful. + 150 Opening ASCII mode data connection for rfc959.txt (147316 bytes). + 226 Transfer complete. + local: rfc959.txt remote: rfc959.txt + 151249 bytes received in 0.9 seconds (1.6e+02 Kbytes/s) + ftp> quit + 221 Goodbye. + atlas.arc.nasa.gov% + + + + + + + + +IAFA Working Group [Page 4] + +RFC 1635 How To FTP May 1994 + + +Variations + + The above example is of the FTP program available on UNIX systems. + Other operating systems also make FTP programs available. The actual + commands you type may vary somewhat with other programs. However, in + general, you will do the following with every FTP program: + + - Log in to your local host, and invoke the FTP program. + + - Open a connection to the host (using either the host name + or its IP address) + + - Once connected to the remote host, log in with username + "anonymous". + + - Provide either the password "guest" or whatever the password the + site requests. + + - Issue whatever FTP commands you require, such as those to + change directories or to retrieve a file. + + - When finished, exit the FTP program, which will close your + connection to the archive host. + +Friendly Servers + + These days, many sites are using a form of FTP that allows them to + display several lines of explanatory text that help direct users + through their archive. The listing of alternative services on + naic.nasa.gov is an example. If these effusive servers confuse the + client you are using, try typing a hyphen ( - ) before your password + when you log in. That should disable the verbose mode of the server. + +Other FTP Commands + + We have demonstrated some of the commands available with FTP + programs. Many others are possible. For example, once you have + logged in to a remote host: + + - You may ask the FTP program to display a list of available + commands, typically by invoking the FTP program without + arguments and typing "help". + + - You may view the contents of the directory to which you are + connected. Type "dir" or "ls" to do so. + + - You may rename a file by using the "get" command's + optional local file name, which follows the remote file + + + +IAFA Working Group [Page 5] + +RFC 1635 How To FTP May 1994 + + + name on the command line. You probably should rename a + file when the remote file name exceeds your local file + system's naming constraints, e.g., if the remote file + name is too long. An example of using the "get" command + to rename a file when transferring it might be "get + really-long-named-file.txt short.txt". + + - You may set BINARY mode to transfer executable programs or files + of data. Type "binary" to do so. Usually + FTP programs assume files use only 7 bits per byte, the norm for + standard ASCII-encoded files. The BINARY command allows you to + transfer files that use the full 8 bits per byte without error, + but this may have implications on how the file is transferred + to your local system. + + If you are not sure what format a file is in, you may need to + transfer it a second time in the other mode (BINARY or ASCII) + if your first guess is wrong. The extension at the end of the + file name may give you a clue. File name extensions are + described below. + + Because some machines store text files differently than others, + you may have to try your luck if you're not sure what format + a file is in. A good guess is to try ASCII mode first, if + you have grounds to suspect the file is a text file. Otherwise, + try BINARY mode. Try TENEX mode as a last resort. + + - You may transfer multiple files at the same time. To set this + mode, type "mget". You then supply a file name pattern that + the remote system understands and it tries to transfer each + file in turn. If your local FTP user agent cannot transform + the remote file names into legal local file names, or if there + are some files that must be transferred in ASCII mode and others + that must be transferred in BINARY mode, you may not be able to + take advantage of this facility. + + Full details on the commands and options available are in the FTP + documentation that comes with your system. You can also type "help" + at the FTP command prompt for a list of command options. + + A copy of the UNIX version of the FTP documentation is available from + the online manual. If your UNIX site has the manuals installed, type + the following at the UNIX prompt: + + % man ftp + + + + + + +IAFA Working Group [Page 6] + +RFC 1635 How To FTP May 1994 + + +The Packaging and Naming of Files + + Several widely used conventions allow for efficient storage and + transmission of information stored at archive sites. + + Information stored on archive sites is often "transformed" in three + common ways. "Compressing" (reducing the size of) the stored + information makes more space available on the archive, and reduces + the amount of data actually transferred across the network. + "Bundling" several files into one larger file maintains the internal + directory structure of the components, and allows users to transfer + only one larger object rather than several (sometimes hundreds) of + smaller files. + + In addition, binary data is often converted into an ASCII format for + transmission, a process referred to in this document as + "transformation". Traditionally, Internet RFC 822-based electronic + mail and USENET protocols did not allow the transmission of "binary" + (8-bit) data; therefore, files in binary format had to be transformed + into printable 7-bit ASCII before being transmission. + + On many systems, various file naming conventions are used to help the + remote user to determine the format of the stored information without + first having to retrieve the files. Below we list the more common + compression, bundling, and transformation conventions used on the + Internet. This list is not intended to be exhaustive. In all cases + public domain or freely-available implementations of the programs + associated with these mechanisms are available on the network. + + 1) compress/uncompress + + Filenames terminating in ".Z" normally signify files that have been + compressed by the standard UNIX Lempel-Ziv "compress" utility. + There is an equivalent program called "uncompress" to reverse the + process and return the file to its original state. No bundling + mechanism is provided, and the resulting files are always in binary + format, regardless of the original format of the input data. + + 2) atob/btoa + + Performs a transformation of ASCII to binary (atob) and the reverse + (btoa) in a standard format. Files so transformed often have + filenames terminated with ".atob". No bundling or compression + mechanisms are used. + + + + + + + +IAFA Working Group [Page 7] + +RFC 1635 How To FTP May 1994 + + + 3) atox/xtoa + + A data transformation standard used to convert binary + files to transferable ASCII format. Sometimes used in + preference to other similar mechanisms because it is more + space efficient; however, it is not a compression + mechanism per se. It is just more efficient in the + transformation from one format to the other. Filenames of + files in this format often have the ".atox" extension. + + 4) uuencode/uudecode + + Transforms binary to ASCII ("uuencode") and the reverse + ("uudecode") transformation in a standard manner. + Originally used in the UUCP ("Unix to Unix CoPy") + mail/USENET system. No bundling or compression mechanisms + are used. Naming conventions often add a .uu at the end + of the file name. + + 5) tar/untar + + Originally a UNIX based utility for bundling (and + unbundling) several files and directories into (and from) + a single file (the acronym stands for "Tape ARchive"). + Standard format provides no compression mechanism. The + resulting bundled file is always in binary format + regardless of whether the constituent files are binary or + not. Naming conventions usually hold that the filename of + a "tarfile" contain the sequence ".tar" or "-tar". + + 6) zip/unzip + + Often used in IBM PC environments, these complementary programs + provide both bundling and compression mechanisms. The resulting + files are always in binary format. Files resulting from the "zip" + program are by convention terminated with the ".zip" filename + extension. + + 7) arc/unarc + + Often used in IBM PC environments, these complementary programs + provide both bundling and compression mechanisms. The resulting + files are always in binary format. Files stored in this format + often have a ".arc" filename extension. + + + + + + + +IAFA Working Group [Page 8] + +RFC 1635 How To FTP May 1994 + + + 8) binhex + + Used in the Apple MacIntosh environment, the binhex + process provides bundling as well as binary to ASCII data + transformations. Files in this format by convention have + a filename extension of ".hqx". + + 9) shar + + Bourse shell archives package text or binary files into a + single longer file which, when executed, will create the + component files. Because this format is vulnerable to + misuse, most users use a special tool called unshar to + decode these archives. By convention, files in this + format have a filename extension of ".shar". + + 10) VMS_SHARE + + DCL archives package text or binary files into a single + longer file which, when executed, will created the + component files. Because this format is vulnerable to + misuse, care must be take to examine such an archive + before executing it. By convention, files in this format + have a filename extension of ".shar". + + 11) Multipart shar/vms_share files + + Sometimes these shell archive files are broken into + multiple small parts to simplify their transfer over other + forms of fileservers that share the same archive tree. In + such cases, the parts of the files are usually suffixed + with a part number (e.g., xyz.01 xyz.02 xyz.03 ... or even + .01-of-05). Collect all the parts, concatenate them on + your local system, and then apply the procedure listed + above for a simple shar or vms_share file to the + concatenated file you just made. + + 12) zoo + + The zoo program implements compression/decompression and + bundling/unbundling in a single program. Utilities + supporting the zoo format exist on a wide variety of + systems, including Unix, MS-DOS, Macintosh, OS/2, Atari + ST, and VAX VMS. Files created by the "zoo" programs by + convention end with the ".zoo" filename extension. Zoo is + a popular distribution format due to the availability of + free implementations (both source and executable code) on + a wide variety of operating systems. + + + +IAFA Working Group [Page 9] + +RFC 1635 How To FTP May 1994 + + + 13) gzip/gunzip + + The Free Software Foundation GNU project adopted a variant + of the zip compression mechanism as a substitute for the + compress/uncompress commands. The resulting files are + always in binary format. Files resulting from the "gzip" + program are by convention terminated with the ".z" or + ".gz" filename extensions. The gunzip program also + recognizes ".tgz" and ".taz" as shorthands for ".tar.z" or + ".tar.Z". Also, gunzip can recognize and decompress files + created by the gzip, zip, compress, or pack commands. + + The GNU project recently began distributing and using the + gzip/gunzip utilities. Even more recently they changed + the default suffix from .z to .gz, in an attempt to (1) + reduce confusion with .Z, and (2) eliminate a problem with + case-insensitive file systems such as MS-DOS. The gzip + software is freely redistributable and has been ported to + most UNIX systems, as well as Amiga, Atari, MSDOS, OS2, + and VMS systems. + + In some cases, a series of the above processes are performed to + produce the final file as stored on the archive. In cases where + multiple transformation processes have been used, tradition holds + that the original (base) filename be changed to reflect these + processes, and that the associated filename extensions be added in + the order in which the processes were performed. For example, a + common procedure is first to bundle the original files and + directories using the "tar" process, then to "compress" the bundled + file. Starting with a base file name of "foobar", the file name in + the archive would become "foobar.tar.Z". As this is a binary file, + it would require a further transformation into printable ASCII by a + program such as "uuencode" in order to be transmitted over + traditional email or USENET facilities, so it might finally be called + "foobar.tar.Z.uu." + + Some operating systems can not handle multiple periods; in such cases + they are often replaced by hyphen ( - ), underscore ( _ ), or by + detailed instructions in the "read me" files in the directories. + +Compress and Tar + + Here is an example of the use of the "compress/uncompress" and + "tar/untar" programs. + + Suppose "patch" is a useful public domain program for applying + program patches and updates. You find this file at an archive site + as "patch.tar.Z". Now you know that the ".Z" indicates that the file + + + +IAFA Working Group [Page 10] + +RFC 1635 How To FTP May 1994 + + + was compressed with the UNIX "compress" command, and the ".tar" + indicates that it was tar'ed using the UNIX "tar" tape archive + command. + + First retrieve the file onto your machine using anonymous FTP. To + unpack this program, you would first uncompress it by typing: + + uncompress patch.tar.Z + + This will uncompress the file, and in the process, rename it to + "patch.tar". You can then execute the "tar" command to extract the + individual files. + + In the example of patch.tar, you could invoke the command as: + + %tar xvf patch.tar + + The files would be extracted (that's the 'x' argument to tar) from + the file patch.tar (that's the 'f' argument). Because we use the 'v' + (for verbose) argument, the name of each file is printed as it is + extracted. When tar is complete you should have all the files that + make up the "patch" program in your working directory. + +Etiquette + + Not every site that supports FTP permits anonymous tranfers. It is + wrong to try to get files from systems that have not advertised the + availability of such a service. + + Remember that Internet site administrators for archive sites have + made their systems available out of a sense of community. Rarely are + they fully compensated for the time and effort it takes to administer + such a site. There are some things users can do to make their jobs + somewhat easier, such as checking with local support personnel first + if problems occur before asking the archive administrator for help. + + Most archive machines perform other functions as well. Please + respect the needs of their primary users and restrict your FTP access + to non-prime hours (generally between 1900 and 0600 hours local time + for that site) whenever possible. It is especially important to + remember this for sites located on another continent or across a + significant body of water because most such links are relatively slow + and heavily loaded. + + + + + + + + +IAFA Working Group [Page 11] + +RFC 1635 How To FTP May 1994 + + + In addition, some sites offering anonymous FTP limit the number of + concurrent anonymous FTP logins. If your attempt to log onto such a + site results in an error message to the effect that too many + anonymous FTP users are online, you should wait a while before + attempting another connection rather than retrying immediately. + + To reduce redundant storage, you should find out how to make useful + the files you fetch using FTP available to your entire organization. + If you retrieve and test a program that turns out to be useful, you + should probably ask your administrator to consider making the program + generally available, which will reduce the redundant effort and disk + space resulting from multiple individuals installing the same package + in their personal directories. + + If you find an interesting file or program on an archive site, tell + others about it. You should not copy the file or program to your own + archive unless you are willing to keep your copy current. + +References + + [1] Postel, J., and J. Reynolds, "File Transfer Protocol (FTP)", STD + 9, RFC 959, USC/Information Sciences Institute, October 1985. + +Security Considerations + + Security issues are not discussed in this memo. + + + + + + + + + + + + + + + + + + + + + + + + + +IAFA Working Group [Page 12] + +RFC 1635 How To FTP May 1994 + + +Authors' Addresses + + Peter Deutsch + Bunyip Information Systems + 266 Blvd. Neptune + Dorval, Quebec, H9S 2L4 + Canada + + Phone: (514) 398-3709 + EMail: peterd@bunyip.com + + + Alan Emtage + Bunyip Information Systems + 266 Blvd. Neptune + Dorval, Quebec, H9S 2L4 + Canada + + Phone: (514) 398-3709 + EMail: bajan@bunyip.com + + + April N. Marine + NASA NAIC + M/S 204-14 + Ames Research Center + Moffett Field, CA 94035-1000 + + Phone: (415) 604-0762 + EMail: amarine@atlas.arc.nasa.gov + + + + + + + + + + + + + + + + + + + + + +IAFA Working Group [Page 13] + |