Netork Working Group L. Peter Deutsch Request For Comments: 606 PARC-MAXC December 1973 Host Names On-line Now that we finally have an official list of host names, it seems about time to put an end to the absurd situation where each site on the network must maintain a different, generally out-of-date, host list for the use of its own operating system or user programs. For example, each of the TENEX sites to which I have access ( SRI-ARC, BBN-TENEX, USC-ISI, and PARC-MAXC) has a slightly different mapping between host names and host addresses: none is complete, and I believe each one differs in some way from the official List. Since the NIC has responsibility for maintaining the official list, lt seems appropriate for them to maintain an on-line file, accessible to anyone, which Lists names and host addresses ( and certain other information which I will suggest in a moment) in an easily machine-readable form. This rules out, in my opinion, providing this information only in the form of an NLS structured file, since there are no facilities for accessing such files from the network and since many sites would not want to accommodate themselves to this structure even if there were. The file I have in mind would be devoted principally to that information needed by programs, as opposed to people, since the ; former want their information in compact, easily parsed form, whereas the latter appreciate more verbose expression and more sophisticated facilities for browsing or querying. Therefore, I propose that the following information be included in such a file: Of course, the official name and host address for each host. This would be the primary content of each entry. Some information about the options of the various protocols supported by the host, including ( for FTP ) the preferred byte size and ( for TELNET) the preferred duplex mode. The former can have an enormous effect on the efficiency of file transfers. Since the new TELNET allows negotiation of options, the list need not be complete or accurate. The function o f the host vis-a-vis the network ( user, server, TIP, etc.). This may aid NCPs in deciding whether to poll the host or give useful information for statistical purposes ( e.g. I would like to make my NCP collect statistics on traffic with TIPs vs. other hosts). Since the file will be generated centrally by a single program, but used widely by a variety of programs, it follows that its format should be organized for ease of interrogation at the expense of ease of construction. I feel a reasonable way to achieve this is to store it as an ASCII text file with the logical structure of a "property list".
In other words, aside from the two basic facts in each entry ( name and address), the information will be expressed in the form of <attribute, value> pairs rather than having the attribute be recognized by format, position, etc. l don't believe it matters a great deal exactly how this file is formatted, so I will make a suggestion in the hope that no one cares enough to protest it. ( This has never worked before in the history of the network, but it' s still worth a try ) The following is the proposed syntax of the file. <host-name-file> ::= <entry> | <host-name-file> <entry> <entry> ::= <data-part> <end-of-line> Note that this produces a blank line after the <data-part>. <data-part> ::= <basic-part> | <data-part> <attribute-item> <basic-part> ::= <host-name> , <host-address> <end-of-line> <attribute-item> ::= <attribute-name> = <attribute-value> <end-of-line> This leaves the following terms undefined: <end-of-line>: I don't know what end-of-line indication is in favor in the network community these days. I personally favor carriage-return followed by line-feed. TENEX tends to use the single character octal 37, which is totally non-standard and inappropriate for this application. <host-name>: an official host name as specified in the recent RFC 597 (NIC 20826) by NJN and JAKE. It is my understanding that these names are restricted to letters, digits, hyphens, and parentheses ( including the network name). <host-address>: a decimal host address, relative to its own network ( I would assume). There has been no general discussion of multi-network addressing -- although there is apparently an unpublicized Internetworking Protocol experiment in progress -- and some other convention may be more desirable. <attribute-name>: an arbitrary name containing only letters, digits, and hyphens. We will have to agree on some names like BEST-FTP-BYTE-SIZE (?), but I am willing to let the NIC pick them. <attribute-value>: an arbitrary string not containing <end--of-line>, whose interpretation depends in general on the attribute. For example, there might be an attribute SERVERS whose value was a list of the servers customarily run by the site. The following are some specific attributes that I think would be worthwhile: NICKNAMES -- value is a list of acceptable nicknames for the host. Any system that provides name-to-address translation is encouraged ( although of course not required) to accept these names as alternatives to the official host name.
FTP-BYTE-SIZES -- value is a list of the byte sizes supported by the FTP server. The first byte size is the one which leads to the least computational overhead ( e.g. 36 for PDP-1O's, 32 for 36O's). ECHOING -- value is L or R depending on whether the host expects the terminal to echo ( Remote) or expects to do its own echoing (Local). Note that no attribute is actually required and that the values under a given attribute need not be complete. In other words, this list is meant not to replace option negotiation, word-of-mouth, or any other means bo which one host discovers the properties of another, but merely to provide an alternate source of information which can be accessed in a simple and uniform way. I realize that there is a time-honored pitfall associated with suggestions such as the present one: it represents a specific solution to a specific problem, and as such may not be compatible with or form a reasonable basis for more general solutions to more general problems. However, ( 1) this particular problem has been irking me and others I have spoken to for well over a year, and it is really absurd that it should have gone unsolved this Long; (2) no one seems particularly interested in solving any more general problem. Except the Datacomputer: PLEASE, if there is an easy way to accomplish the same function through the Datacomputer, someone write un RFC specifying it.