Elizabeth Feinler RFC 810
Ken Harrenstien 1 March 1982
Zaw-Sing Su References: RFC 811, 796
Vic White Obsoletes: RFC 608
Network Information Center
SRI International
DoD INTERNET HOST TABLE SPECIFICATION
INTRODUCTION
The ARPANET Official Network Host Table, as outlined in RFC 608, no
longer suits the needs of the DoD community, nor does it follow a
format suitable for internetting. This paper specifies a new host
table format applicable to both ARPANET and Internet needs.
In addition to host name to host address translation and selected
protocol information, we have also included network and gateway name
to address correspondence, and host operating system information.
This Host Table is utilized by the DoD Host Name Server maintained by
the ARPANET Network Information Center (NIC) on behalf of the Defense
Communications Agency (DCA) (RFC 811). It obsoletes the host table
described in RFC 608.
LOCATION OF THE STANDARD DoD ONLINE HOST TABLE
A machine-translatable ASCII text version of the new DoD Host Table
is online in the file HOSTS.TXT on the SRI-NIC host. It can
be obtained by connecting to host SRI-NIC (10.0.0.73) from your local
FTP server, logging in as user=ANONYMOUS, password=GUEST, and doing a
'get' on HOSTS.TXT. The same table may also be obtained via
the NIC Host Name Server.
NOTE: See Appendix A. for timeframe for cutover.
ASSUMPTIONS
1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
to 24 characters drawn from the alphabet (A-Z), digits (0-9), and the
minus sign (-) and period (.). No blank or space characters are
permitted as part of a name. No distinction is made between upper
and lower case. The first character must be a letter. The last
character must not be a minus sign or period. A host which serves as
a GATEWAY should have "-GATEWAY" or "-GW" as part of its name. A
host which is a TIP or a TAC should have "-TIP" or "-TAC" as part of
its host name, if it is an ARPANET or DoD host.
2. Internet Addresses are 32-bit addresses (RFC 796). In the host
table described herein each address is represented by four decimal
numbers separated by a period. Each decimal number represents 1
octet.
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Host Table Specification
3. If the first bit of the first octet of the address is 0 (zero),
then the next 7 bits of the first octet indicate the network number
(Class A Address). If the first two bits are 1,0 (one,zero), then
the next 14 bits define the net number (Class B Address). If the
first 3 bits are 1,1,0 (one,one,zero), then the next 21 bits define
the net number (Class C Address) (RFC 796).
This is depicted in the following diagram:
+--------------+-----------------------------------------------+
|0| NET <-7-> | LOCAL ADDRESS <-24-> |
+--------------+-----------------------------------------------+
+---+--------------------------+-------------------------------+
|1 0| NET <-14-> | LOCAL ADDRESS <-16-> |
+---+--------------------------+-------------------------------+
+-----+----------------------------------------+---------------+
|1 1 0| NET <-21-> | LOCAL ADDRESS |
+-----+----------------------------------------+---------------+
4. The LOCAL ADDRESS portion of the internet address identifies a
host within the network specified by the NET portion of the address.
5. For the ARPANET (a Class A network), the NET address is 10
(decimal) and the LOCAL ADDRESS maps as follows: the second octet
defines the physical host, the third octet defines the logical host,
and the fourth defines the IMP.
+-+-------------+---------------+--------------+---------------+
|0| 10 | HOST | LOGICAL HOST | IMP |
+-+-------------+---------------+--------------+---------------+
(NOTE: RFC 796 describes the local address mappings for several
other networks.)
6. It is the responsibility of the user using this host table to
translate it into whatever format is needed for his or her purposes.
7. Names and Addresses for DoD networks, gateways, and hosts will be
negotiated and registered with the Network Information Center
(NIC@SRI-NIC or (415) 859-4775) before being used and before traffic
is passed by a DoD host. For an interim period the NIC will attempt
to keep similar information for non-DoD networks and hosts if this
information is provided, and as long as it is needed, i.e., until
intercommunicating network name servers are in place.
EXAMPLE OF NEW HOST TABLE FORMAT
NET : 10.0.0.0 : ARPANET :
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Host Table Specification
NET : 18.0.0.0 : LCSNET :
GATEWAY : 10.0.0.77, 18.8.0.4 : MIT-GW :: MOS : IP/GW :
HOST : 10.0.0.73 : SRI-NIC,NIC : FOONLY-F3 : TENEX :
NCP/TELNET,NCP/FTP, TCP/TELNET, TCP/FTP :
HOST: 10.2.0.11 : SU-TIP,FELT-TIP :::
SYNTAX AND CONVENTIONS
; (semicolon) is used to denote the beginning of a comment.
Any text on a given line following a ';' is
comment, and not part of the host table.
NET keyword introducing a network name/address entry
GATEWAY keyword introducing a gateway name/address entry
HOST keyword introducing a host name/address entry
: (colon) is used as a field delimiter
:: (2 colons) indicates a null field
, (comma) is used as a data element delimiter
XXX/YYY indicates protocol information of the type
TRANSPORT/SERVICE.
where TRANSPORT/SERVICE options are specified as
"FOO/BAR" - both transport and service known
"FOO" - transport known; services not known or not
running, OR
"BAR" - name is known, what it does is not
NOTE: See Appendices B and C for specific options and
acronyms.
Each host table entry is an ASCII text string comprised of 6 fields,
where
Field 1 = KEYWORD indicating whether this entry pertains
to a NET, GATEWAY, or HOST. NET entries cannot have
alternate addresses or nicknames.
Field 2 = Internet Address of Network, Gateway, or Host
followed by alternate addresses
Field 3 = Official Name of Network, Gateway, or Host
(with optional nicknames)
Field 4 = Machine Type
Field 5 = Operating System
Field 6 = Protocol List
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Host Table Specification
Fields 4, 5 and 6 are optional.
Fields 3-6, if available, pertain to the first address in Field 2.
'Blanks' (spaces and tabs) are ignored between data elements or
fields, but are disallowed within a data element.
Each entry ends with a colon.
The host table will be sorted by internet address.
GRAMMATICAL HOST TABLE SPECIFICATION
A. Parsing grammar
::= ":" ":" [":" []
[":" [] [":" [] ]]] ":"
::= *["," ]
::= "." "." "."
::= <0 to 255 decimal>
::= |
| *["," ]
::=
::=
::=
::=
::= *["," ]
::= "/" |
B. Lexical grammar
::= [ ]
::=
::= NET | GATEWAY | HOST
::= [*[]]
::= PDP-11/70 | DEC-1080 | C/30 | CDC-6400...etc.
::= ITS | MULTICS | TOPS20 | UNIX...etc.
::= TCP | NCP | UDP | IP...etc.
::= TELNET | FTP | SMTP | MTP...etc.
::=
::= ";"
Notes:
1. Zero or more 'blanks' between separators " , : " are allowed.
'Blanks' are spaces and tabs.
2. Continuation lines are lines that begin with at least one
blank. They may be used anywhere 'blanks' are legal to split an
entry across lines.
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BIBLIOGRAPHY
1. Feinler, E. and Kudlick, M. Host Names Online, RFC 608,
Network Information Center, SRI International, Jan. 1973.
2. Postel, J. Assigned Numbers, RFC 790, Information Sciences
Inst., Univ. of Southern Calif., Marina Del Rey, Sept. 1981.
3. Postel, J. Internet Protocol, RFC 791, Information Sciences
Inst., Univ. of Southern Calif., Marina Del Rey, Sept. 1981.
4. Postel, J. Address Mappings, RFC 796, Information Sciences
Inst., Univ. of Southern Calif., Marina Del Rey, Sept. 1981.
5. Feinler, E., Harrenstien, K., Su, Z. and White, V. Official
DoD Internet Host Table Specification, RFC 810, Network
Information Center, SRI International, March 1, 1982.
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APPENDIX A. CUTOVER DETAILS
The cutover date for use of the new host table is 1 May 1982. The
table below indicates which files will contain the old or the new
versions of the host table for what period of time. After 1 August
1982, the old format for HOSTS.TXT (specified in RFC-608)
will no longer be supported.
--------------------------------------------------------------------
May 1982 June-July 1982 August 1982 on
--------------------------------------------------------------------
HOSTS.TXT HOSTS.TXT HOSTS.TXT
old version new version new version
NHOSTS.TXT NHOSTS.TXT old version
new version (test) new version discontinued
OHOSTS.TXT OHOSTS.TXT
old version old version
--------------------------------------------------------------------
These periods of overlap should give implementors time to make the
necessary changes to programs accessing this file.
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APPENDIX B. TRANSPORT/SERVICE OPTIONS AND ACRONYMS
Current TRANSPORT/SERVICE options are:
IP TCP/FTP
IP/GW TCP/MTP
NCP TCP/NNS
NCP/FTP TCP/RJE
NCP/RJE TCP/SMTP
NCP/SMTP TCP/TELNET
NCP/TELNET TCP/TFTP
NCP/NNS UDP
NVP
TCP
Note: "TCP" implies IP is also implemented
Acronym definitions for the above protocol options are:
FTP - File Transfer Protocol
GW - Gateway Protocol
IP - Internet Protocol
MTP - Mail Transfer Protocol
NCP - Network Control Protocol
NNP - NIC Internet Name Server Protocol
NVP - Network Voice Protocol
RJE - Remote Job Entry Protocol
SMTP - Simple Mail Transfer Protocol
TELNET - TELNET Protocol
TCP - Transmission Control Protocol
TFTP - Trivial File Transfer Protocol
UDP - User Datagram Protocol
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APPENDIX C. OPERATING SYSTEM ACRONYMS
Current operating system acronyms are:
ASP KRONOS RSX11M VMS
AUGUST MCP RT11 WAITS
BKY MOS SCOPE
CCP MPX-RT SIGNAL
DOS/360 MULTICS SINTRAN
ELF MVT TENEX
EPOS NOS TOPS10
EXEC-8 NOS/BE TOPS20
GCOS OS/MVS TSS
GPOS OS/MVT UNIX
ITS RIG VM/370
INTERCOM RSX11 VM/CMS
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RFC, FYI, BCP