RFC4707
Network Working Group P. Grau Request for Comments: 4707 V. Heinau Category: Experimental H. Schlichting
R. Schuettler
Freie Universitaet Berlin
October 2006
Netnews Administration System (NAS)
Status of This Memo
This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
IESG Note
This RFC is not a candidate for any level of Internet Standard. The IETF disclaims any knowledge of the fitness of this RFC for any purpose, and in particular notes that the decision to publish is not based on IETF review for such things as security, congestion control or inappropriate interaction with deployed protocols. The RFC Editor has chosen to publish this document at its discretion. Readers of this document should exercise caution in evaluating its value for implementation and deployment.
Abstract
The Netnews Administration System (NAS) is a framework to simplify the administration and usage of network news (also known as Netnews) on the Internet. Data for the administration of newsgroups and hierarchies are kept in a distributed hierarchical database and are available through a client-server protocol.
The database is accessible by news servers, news administrators, and news readers. News servers can update their configuration automatically; administrators are able to get the data manually. News reader programs are able to get certain information from an NAS server, automatically or at a user's discretion, which provides detailed information about groups and hierarchies to the user.
NAS is usable in coexistence with the current, established process of control messages; an unwanted interference is impossible. Furthermore, NAS is able to reflect the somewhat chaotic structure of Usenet in a hierarchical database. NAS can be used without modification of existing news relay, news server, or news reader software; however, some tasks will be better accomplished with NAS- compliant software.
Contents
- 1 Introduction
- 2 Overview
- 3 Protocol Level
- 4 Description of Functions
- 5 Definitions
- 6 Specification of the NAS Protocol (TCP)
- 7 Specification of the NAS Protocol (UDP)
- 8 IANA Considerations
- 9 Security Considerations
Introduction
An increasing number of newsgroups, hierarchies, and articles has made the administration of news servers a complex and time-consuming task. The tools for the administration have remained unchanged for ten years and are no longer appropriate. Many hierarchies are inconsistent; many new newsgroups are not created or only with a large delay; removed groups keep lurking in the configuration files for a long period of time. There is no administration tool that utilizes the power of the Internet, and it is not possible to check the consistency of the news server at a given point of time.
Users find it difficult to get an overview of the newsgroups, the charter of a particular one, which language is preferred, or whether a group is moderated. Renaming, the status change from moderated to unmoderated or vice versa, and the splitting of a group into several others are dynamic processes. These processes are in common use, but it takes a long time until every news server is aware of these changes.
An increasing number of faked control messages has appeared in the last few years. Purposely or accidentally, control messages were sent to foreign news servers to create or remove a certain group, although this was not approved according to the rules of the hierarchy in question. Due to this fact, automatic creation and removal are disabled on many news servers, and several dead groups have not been deleted. It is very difficult for users to determine the current status of a group, and in some cases they simply cannot tell that the group they are posting to is not an active group but a dead or invalid one.
It is the design goal of Netnews Administration System (NAS) to provide an out-of-band system that helps to maintain, propagate, and deliver the required information. There will not be any interference with current protocols and standards. It is not intended to make use of control messages or some special Network News Transfer Protocol (NNTP) commands. The advantage of NAS is that it provides more information in a more structured format than that of control messages. Not only news server administrators but also Usenet users can get more detailed information about newsgroups and hierarchies.
Due to the fact that a client connects to a server and the server asks for authentication, this is a more reasonable procedure for transmitting information than that for control messages.
Furthermore, it is possible to check for changes on a regular basis at customized intervals to keep local data up-to-date.
Overview
NAS is based on a database that contains information about certain groups and hierarchies. This database is structured in a hierarchical manner and distributed to various servers, and it is able to receive queries at any time. The service is comparable to directory services like DNS, Lightweight Directory Access Protocol (LDAP), or Network Information Service (NIS). The NAS protocol is inspired by protocols like NNTP and SMTP. The port 991 is reserved for NAS and registered by the Internet Assigned Numbers Authority (IANA) [IANA-PN].
The organizational structure of NAS is hierarchical; this means that a NAS root server collects data from the sub-servers that are authoritative for certain hierarchies. The root server signs the data and distributes it authoritatively. Replication of database entries is possible. The hierarchical structure can consist of multiple levels. Usage of the database is possible for news servers, news readers, and special client programs. The communication is based on TCP and UDP.
Taking the real world into account, there might be some policy problems with a single root server. But it is possible to establish a structure like that of the current Usenet system, where some hierarchies have a good administration with a well-defined system of rules, and where some are not well maintained. The goal is to get as much information as possible under one hat, but there can be no "official" force to achieve this.
During the startup phase, it is quite likely that there will be a root server, handling just hierarchies with strict rules and accepted authorities (e.g., BIG8, de.*, us.*, bln.*, fr.*, it.*).
However, it is also imaginable to have some NAS servers providing data on, for example, alt.!binaries, some providing data on alt.*, and even some providing alt.* following special policies or sets of rules.
An administrator using NAS will have the choice to use just one root server (and all its data) or to use another NAS server for special hierarchies.
. NAS server. . NAS server. . NAS server .
. . . . . alt.*, .
. alt.* . . Big8 . . !alt.binaries.*.
. database . . database . . database .
^ ^ ^ ^
`--+ +--' `------+ +----'
| | | |
.------------. .------------.
| NAS client | | NAS client |
+------------+ +------------+
| netnews | | netnews |
| server | | server |
.------------. .------------.
Configuration A Configuration B
Figure 1
NAS contains information about newsgroups and complete hierarchies. Furthermore, it contains information about the hierarchies' inheritable entries and default values for a single newsgroup.
Protocol Level
It is expected that the real-life use of NAS will change the requirements for the Netnews Administration System. On the one hand, the protocol has to be extensible and flexible in order to implement improvements; on the other hand, it must ensure compatibility between different versions. A simultaneous migration of all sites using NAS to a new protocol version is not likely to happen. To solve this problem, NAS has a protocol level. This protocol level describes the current functionality. The protocol level, being a number between 1 and 32767, is negotiated at connection setup. Enhancements and modifications must use a different protocol level than that of their predecessors. (Usually the protocol level is incremented by 1 with every new version of the protocol specification.) Every current or future implementation MUST be compatible with protocol level 1 in order to fall back to this level if communication on a higher level fails.
An implementation of higher protocol levels should be able to emulate the behavior of lower levels, even if this implies a loss of features. The negotiation of the protocol level between client and server is described in the specification of the command VERS. If there is no agreement on the protocol level, only commands of the
protocol level 1 MUST be used. Documents enhancing or modifying the NAS standard MUST specify on which level these changes take place and how the behavior should be in other protocol levels.
This document describes protocol level 1.
Description of Functions
In order to use an NAS server, a connection must be opened by the client. The NAS server can be located in the same domain or somewhere else on the Internet.
The NAS system is hierarchical. The idea is to have an NAS root server like the DNS root servers. The root server distributes the data collected from client NAS servers that are authoritative servers for their hierarchy. The maintenance of the authoritative data is possible on any system. The root server collects the data and makes them available to other servers, which can in turn distribute these data to other servers. The administrator has the opportunity to make use of either all data or only parts of the database. NAS servers can ask multiple NAS servers for data. An attached time stamp makes it possible to distinguish between new and old data and to avoid loops in the propagation.
To describe the NAS in greater detail, it is necessary to emphasize the hierarchical design of the NAS system. The following figure shows the propagation of data along the server hierarchy.
Authoritative data for a newsgroup or a hierarchy are collected and written into a database. These data are available through a local NAS server and are collected from this authoritative server by upstream NAS servers.
There may also be NAS servers that are not authoritative servers; these servers merely provide the information they collect from other NAS servers to clients such as news servers, administration programs, and news readers.
. root NAS.-------------------------+
. server .----------------+ |
. database. | |
| | | . NAS server .
| |distributes | . authoritative for de.*.
| | | . database .
. NAS server. `--------+
^ ^ ^ . authoritative for bln.*.
q | | `--| netnews | . database .
e | | .---------.
r | |
i | | .---------.
e | `--| admin |
s | | program |
| .---------.
|
| .---------.
`--| news |
| reader |
.---------.
Figure 2
Requests to an NAS server originating at a client (as well as at another server) are accomplished in several steps: establishing a connection, authentication (optional), negotiating a protocol level (optional), queries on the database, and termination.
Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119.
Specification of the NAS Protocol (TCP)
Responses
Overview
An answer starts with a response code (a three-digit number), optionally followed by white space and a textual message. Then the actual text/data follows. Text is sent as a series of successive lines of textual matter, each terminated with CRLF. A single line containing only a single period ('.') is sent to indicate the end of the text (i.e., the server will send a CRLF at the end of the last line of text, a period, and another CRLF).
Answer = response-code [answertext] CRLF
text CRLF
"." CRLF
If the original text contains a period as the first character of the text line, that first period is doubled. Therefore, the client must examine the first character of each line received and, for those beginning with a period, determine either that this is the end of the text or that it should collapse the doubled period to a single one.
Example
<-- INFO --> 101 Information follows
Server: nas.example.org (192.0.2.100) Uptime: 2 weeks, 3 days, 5 hours, 9 minutes Software: NAS 1.0 Client: client.example.org (192.0.2.123) Connection: 9 minutes Highest protocol level supported: 1 Requested protocol level: 1 Protocol level used: 1 .
Response Code Values, Structure, and Meaning
The first digit of the response code indicates the message type (i.e., information, success, warning, error, or data):
1xx Information 2xx Request successful 3xx Request successful, data follow 4xx Request accepted, but no operation possible
5xx Request is wrong (syntax error), is not implemented, or leads to
an internal error
6xx Request successful, data follow until end mark
The second digit specifies the message category:
x0x Connection-related stuff x1x Queries, answers, or data x2x Server-server communication x3x Authentication, authorization x8x Non-standard extensions x9x Debugging output
The actual response code for a specific command is listed in the description of the commands. Answers of the type 1xx, 2xx, 4xx, and 5xx can have a text after the numerical code. 3xx answers contain one or more parameters with data; the exact format is explained in the description of the commands.
An answer to an incorrect request may be longer than one line.
Connection Setup
NAS typically uses port 991, which is reserved by IANA [IANA-PN]. If a connection is set up by the client, the server answers immediately (without a request) with the greeting message, which will start with code 200:
--> 200 Welcome!
nas.example.org ready .
If a connection is refused because the client has no permission to access the server, the answer code is 434. That decision can be made on connection startup based on the client's IP address. When the server is currently out of service, the answer code is 404.
Examples:
--> 434 You have no permission to retrieve data. Good bye.
.
--> 404 Maintenance time
.
After sending a 404 or 434 message, the connection will be closed.
Commands
Structure
A command consists of a command word, sometimes followed by a parameter. Parameters are separated from the command word by white space.
Commands used in the NAS protocol are not case sensitive. A command word or parameter may be uppercase, lowercase, or any mixture of upper- and lowercase.
The length of a command line is not limited. If the need to limit the length of command lines in real-life implementations arises, answer code 513 (line too long) should be returned.
The protocol level described in this document uses command words with a length of exactly four characters each.
In examples, octets sent to the NAS server are preceded by "<-- " and those sent by the NAS server by "--> ". The indicator is omitted if the direction of the dialog does not change.
Overview
The commands described below are defined using the Augmented Backus- Naur Form (ABNF) defined in RFC4234. The definitions for 'ALPHA', 'CRLF', 'DIGIT', 'WSP' and 'VCHAR' are taken from appendix B of RFC4234 and not repeated here.
The following ABNF definitions constitute the set of NAS commands that can be sent from the client to an NAS server.
Detailed Description
Some overall definitions follow:
text = %d1-9 / ; all octets except
%d11-12 / ; US-ASCII NUL, CR and LF
%d14-255
answertext = WSP *( ALPHA / DIGIT / "+" / "-" / "/" / "_" /
"." / "," / ":" / "=" / "?" / "!" / SP )
utc-time = 14DIGIT ; the date and time of the server in UTC
; YYYYMMDDhhmmss
response-code = 3DIGIT ; three digit number
Newsgroup names and hierarchy names are defined according to the following ABNF definitions. Since a hierarchy name can be the same as a newsgroup name (e.g., hierarchy bln.announce.fub.* and newsgroup name bln.announce.fub), there is no difference between the two.
name = plain-component *("." component) component = plain-component / encoded-word encoded-word = 1*( lowercase / DIGIT /
"+" / "-" / "/" / "_" / "=" / "?" )
plain-component = component-start *component-rest component-start = lowercase / DIGIT lowercase = %x61-7A ; letter a-z lowercase component-rest = component-start / "+" / "-" / "_"
NOTE: This definition of newsgroup name is in reference to "News Article Format and Transmission" [SON1036]. When the document "News Article Format" [USEFOR] is established as an RFC, its definitions should be integrated into a higher protocol level of NAS.
HELP
Description
This command prints a short help text on a given command. If called without parameters, it will display a complete list of commands.
help-cmd = "HELP" [WSP commandname] CRLF
commandname = "DATA" / "DATE" / "GETP" / "GETA" /
"HELP" / "HIER" / "INFO" / "LIST" /
"LSTR" / "QUIT" / "VERS"
Possible answers
100: Command overview, command description 410: Indicates that the server is not giving any information
help-answer = "410" [answertext] CRLF
text CRLF
"." CRLF
help-answer =/ "100" [answertext] CRLF
text CRLF
"." CRLF
Examples
<-- HELP
--> 100 NAS server nas.example.org - Version 1.0
Supported commands: DATA - data for a newsgroup DATE - show time of server in UTC GETP - get package GETA - get data from an authoritative server HELP - show this help HIER - data for a hierarchy INFO - show info on current connection LIST - list newsgroups or hierarchies LSTR - recursive list newsgroups or hierarchies QUIT - close the connection VERS - show or set current protocol level
Contact address [email protected] .
<-- HELP LIST --> 100 LIST
LIST - list newsgroups or hierarchies Syntax: LIST hierarchy ... Get a list of newsgroups and sub-hierarchies directly under the parameter hierarchy .
<-- HELP NOOP --> 410
unknown command "NOOP" .
INFO
Description
Prints information about the current connection, the server, and the client.
info-cmd = "INFO" CRLF
Possible answers
101: Normal answer; prints some information about client
and server
400: Indicates that the server is not giving any information
info-answer = "400" [answertext] CRLF
text CRLF
"." CRLF
info-answer =/ "101" [answertext] CRLF
text CRLF
"." CRLF
Examples
<-- INFO --> 101 Information follows
Server: nas.example.org (192.0.2.100) Uptime: 2 weeks, 3 days, 5 hours, 9 minutes Software: NAS 1.0 Client: client.example.org (192.0.2.123) Connection: 9 minutes Highest protocol level supported: 1 Requested protocol level: 1 Protocol level used: 1
End .
<-- INFO --> 400
No information available. .
DATE
Description
Prints the current time of the server in UTC (Universal Coordinated Time) in the format YYYYMMDDhhmmss, followed by an optional comment. The DATE command is only for informational use and to check the server time. For regular transmission of time over the network, the Network Time Protocol (NTP) RFC1305 should be used.
date-cmd = "DATE" CRLF
Possible answers
300: Print the UTC time in specified format; see below 511: Error; print an error message
date-answer = "511" [answertext] CRLF
text CRLF
"." CRLF
date-answer =/ "300" [answertext] CRLF
utc-time [answertext] CRLF
"." CRLF
Examples
<-- DATE --> 300
19990427135230 UTC .
<-- DATE --> 511
Time is unknown .
VERS
Description
The VERS command is used to determine the protocol level to use between client and server. The parameter is a protocol level that the client supports and wants to use. The server will respond with the highest level accepted. This version number MUST not be higher than that requested by the client. Client and server MUST only use commands from the level that the server has confirmed. It is possible, but seldom necessary, to change the protocol level during a session by client request (VERS [protocol level]). When no option is given, the current protocol level will be printed. When no protocol level is negotiated, the protocol level 1 will be used. Commands of a higher level are not allowed without successful negotiation. The protocol level can be followed by an optional comment.
vers-cmd = "VERS" [WSP level] CRLF
level = 1*5DIGIT ; the valid range is 1 - 32767
Possible answers
202: Returns current protocol level 302: Requested level accepted 402: Requested level too high; falling back to lower level 510: Syntax error
vers-answer = "202" [answertext] CRLF
level [answertext] CRLF
"." CRLF
vers-answer =/ "302" [answertext] CRLF
level [answertext] WSP level CRLF
"." CRLF
vers-answer =/ "402" [answertext] CRLF
level [answertext] WSP level CRLF
"." CRLF
vers-answer =/ "510" [answertext] CRLF
level [answertext] CRLF
"." CRLF
Examples
<-- VERS --> 202
2 Current protocol level is 2 .
<-- VERS 2 --> 302
2 My max protocol level is 10 .
<-- VERS 11 --> 402
10 Falling back to level 10 .
<-- VERS BAL --> 510
1 Syntax error .
QUIT
Description
Terminates the connection.
quit-cmd = "QUIT" CRLF
Possible answers
201: Termination of the connection
quit-answer = "201" [answertext] CRLF
Example
<-- QUIT --> 201 Closing connection. Bye.
LIST
Description
To obtain a list of newsgroups and sub-hierarchies in the requested hierarchies, the command LIST is used. The status of the hierarchies is also given. The highest level consists of all top-level hierarchies and is labeled "*". It can be obtained this way, too.
The data consist of a newsgroup- or hierarchy-name/status indicator pair per line. Name and status indicator must be separated by at least one white space. The status indicator is a single word (see Section 6.4). The interpretation is not case sensitive.
list-cmd = "LIST" ( WSP "*" / 1*(WSP name)) CRLF
Possible answers
401: Permission denied 510: Syntax error 610: Normal response with all requested data
list-answer = "610" [answertext] CRLF
*(listdata CRLF)
"." CRLF
list-answer =/ "401" [answertext] CRLF
text CRLF
"." CRLF
list-answer =/ "510" [answertext] CRLF
text CRLF
"." CRLF
listdata = name WSP list-status
The list-status is the status of a newsgroup or hierarchy according to Section 6.4.
list-status = "Complete" /
"Incomplete" /
"Obsolete" /
"Unknown" /
"Unmoderated" /
"Readonly" /
"Moderated" /
"Removed" ; list-status is case-insensitive
Examples
<-- LIST * --> 610 data follow
alt Incomplete comp Complete de Incomplete rec Complete sub Obsolete .
<-- LIST de --> 610 data follow
de.admin Complete de.alt Incomplete de.comm Complete de.comp Complete de.etc Complete de.markt Complete de.newusers Complete de.org Complete de.rec Complete de.sci Complete de.soc Complete de.answers Moderated de.test Unmoderated .
<-- LIST foo --> 610 data follow
foo Unknown .
<-- LIST --> 510 Syntax error
missing parameter hierarchy .
<-- LIST de --> 401 Something is wrong
Permission denied .
LSTR
Description
To obtain a recursive list of newsgroups and sub-hierarchies in the named hierarchy, the command LSTR is used. The status of the hierarchies is also given. The highest level consists of all top- level hierarchies and is labeled "*". It can be obtained this way, too.
The use of "*" as a wildcard pattern following the beginning of a hierarchy name is also possible; so a "LSTR de.a*" would return a list of all newsgroups and hierarchies starting with "de.a".
lstr-cmd = "LSTR" ( WSP "*" / 1*(WSP name ["*" / ".*"]) ) CRLF
Possible answers
401: Permission denied 510: Syntax error 610: Normal answer with all requested data
lstr-answer = "610" [answertext] CRLF
*(listdata CRLF)
"." CRLF
lstr-answer =/ "401" [answertext] CRLF
text CRLF
"." CRLF
lstr-answer =/ "510" [answertext] CRLF
text CRLF
"." CRLF
listdata = name WSP list-status
The list-status is the status of a newsgroup or hierarchy according to Section 6.4.
list-status = "Complete" /
"Incomplete" /
"Obsolete" /
"Unknown" /
"Unmoderated" /
"Readonly" /
"Moderated" /
"Removed" ; list-status is case-insensitive
Example
<-- LSTR de.admin --> 610 recursive mode
de.admin Complete de.admin.infos Moderated de.admin.lists Moderated de.admin.misc Unmoderated de.admin.net-abuse Complete de.admin.net-abuse.announce Moderated de.admin.net-abuse.mail Unmoderated de.admin.net-abuse.misc Unmoderated de.admin.net-abuse.news Unmoderated de.admin.news Complete de.admin.news.announce Moderated de.admin.news.groups Unmoderated de.admin.news.misc Unmoderated de.admin.news.nocem Unmoderated de.admin.news.regeln Unmoderated .
HIER
Description
The command HIER lists all information available about the hierarchy. With the data header "Name", a new data block for each hierarchy is started. The header "Name" gives the name of the hierarchy. The data headers are described in Section 6.3.4. The default is to transmit all available information. It can be limited to a list of desired headers ("Name" and "Status" are always given). A set of comma-separated headers, as an option to the HIER command, will return the requested header fields.
hier-cmd = "HIER" 1*(WSP name) [WSP selection] CRLF
selection = *( "," header ) ; Describes the data fields
; that are requested
header = ALPHA *( ALPHA / "-" ) ; According to section 6.3.4
Example for selection
,Followup,Description : For all entries list Name, Status, Followup
and Description
Possible answers
401: Permission denied
510: Syntax error 611: Regular answer with all requested data
hier-answer = "611" [answertext] CRLF
*(hierdata CRLF)
"." CRLF
hier-answer =/ "510" [answertext] CRLF
*(text CRLF)
"." CRLF
hier-answer =/ "401" [answertext] CRLF
*(text CRLF)
"." CRLF
hierdata = "Name:" WSP text CRLF
"Status:" WSP text CRLF
*(header ":" WSP text CRLF)
[("Ctl-PGP-Key:" CRLF PGP-answer /
"Mod-PGP-Key:" CRLF PGP-answer)]
PGP-answer: The exact format is described in Section 6.7.
Examples
<-- HIER de --> 611 Data coming
Name: de Status: Complete Serial: 20020823120306 Description: Internationale deutschsprachige Newsgruppen Netiquette: http://www.kirchwitz.de.example/~amk/dni/netiquette FAQ: http://www.kirchwitz.de.example/~amk/dai/einrichtung Ctl-Send-Adr: [email protected] Ctl-Newsgroup: de.admin.news.announce Mod-Wildcard: %[email protected] Language: DE Charset: ISO-8859-1 Encoding: text/plain Newsgroup-Type: Discussion Hier-Type: Global Comp-Length: 14 Date-Create: 19920106000000
.
<-- HIER bln --> 401
Permission denied .
<-- HIER --> 510 Syntax error
missing parameter hierarchy .
DATA
Description
The DATA command corresponds to the HIER command, as explained in 6.3.3.8, but it is used for information about a newsgroup. A summary of codes can be found in Section 6.3.4.
data-cmd = "DATA" 1*(WSP name) [WSP selection] CRLF
Possible answers
401: Permission denied 510: Syntax error 612: Regular answer with all requested data
data-answer = "612" [answertext] CRLF
*(datadata CRLF)
"." CRLF
data-answer =/ "510" [answertext] CRLF
text CRLF
"." CRLF
data-answer =/ "401" [answertext] CRLF
text CRLF
"." CRLF
datadata = "Name:" WSP text CRLF
"Status:" WSP text CRLF
*(header ":" WSP text CRLF)
[("Ctl-PGP-Key:" CRLF PGP-answer /
"Mod-PGP-Key:" CRLF PGP-answer)]
Examples
<-- DATA de.comp.os.unix.linux.moderated --> 612 data follow
Name: de.comp.os.unix.linux.moderated
Status: Moderated
Serial: 20020823120312
Description: Linux und -Distributionen.
<[email protected]>
Charter: http://www.dana.de.example/mod/chartas/de.html
Netiquette: http://www.kirchwitz.de.example/~amk/dni/netiquette
Netiquette: ftp://ftp.fu-berlin.de.example/doc/usenet/german /Netiquette Mod-Sub-Adr: [email protected] Mod-Group-Info: http://wpxx02.toxi.uni-wuerzburg.de.example /~dcoulmod/ Newsgroup-Type: Discussion
.
<-- DATA de.foo --> 612 data follow
Name: de.foo Status: Unknown
.
<-- DATA de --> 401
Permission denied .
<-- DATA --> 510 Syntax error
missing parameter newsgroup .
6.3.3.10. GETP
Description
GETP is used for server-server communication. It requests the data for the hierarchy specified by the parameter "name". The format of the data is the same as for the commands "HIER" and "LIST". If "*" is given as hierarchy name, all data the server is offering will be transmitted.
The "timestamp" attached to a package consists of the date and time that the package was created. The timestamp for a package is transmitted together with the package data by the server and marks a specific revision for the package data.
When a client requests a package with GETP, it transmits the timestamp attached to the package in its database so that the server can check whether the data on the client side is still valid or if it is too old. If the data on the client side is still valid, a 213 answer is sent, so the client knows that its data is OK. If the timestamp is "0", the server is forced to transmit the data.
Timestamps set by the server must be increasing and may not be more than 12 hours in the future.
The data for a successful request are signed and sent in ASCII armor according to RFC2440, so a client can check the signature or ignore it. The actual data will be surrounded by the armor start and end sections, according to Section 6.2 of RFC2440.
getp-cmd = "GETP" WSP username WSP password WSP timestamp
WSP ( name / "*" ) CRLF
username = *1( VCHAR ) / "0" ; Length of VCHAR >= 1
password = *1( VCHAR ) / "0" ; Length of VCHAR >= 1
timestamp = utc-time / ; date and time of the last retrieval
"0" ; force the transmission of data
Possible answers
213: Current data at the client side 411: No hierarchy with that name 430: Permission denied 510: Syntax error 613: Hierarchy data
getp-answer = "613" [answertext] CRLF
pgp-ascii-armor-start ; this is according to RFC2440 *(getpdata CRLF) pgp-ascii-armor-end ; this is according to RFC2440 "." CRLF
getp-answer =/ "213" [answertext] CRLF
text CRLF
"." CRLF
getp-answer =/ "430" [answertext] CRLF
text CRLF
"." CRLF
getp-answer =/ "411" [answertext] CRLF
text CRLF
"." CRLF
getp-answer =/ "510" [answertext] CRLF
text CRLF
"." CRLF
pgp-ascii-armor-start and the pgp-ascii-armor-end are built according to RFC2440, Section 6.2., "Forming ASCII Armor".
getpdata = "Name:" WSP text CRLF
"Status:" WSP text CRLF
"Serial:" WSP timestamp CRLF
*(header ":" WSP text CRLF)
[("Ctl-PGP-Key:" CRLF PGP-answer /
"Mod-PGP-Key:" CRLF PGP-answer)]
Examples
<-- GETP 0 0 0 humanities --> 615 data follow
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Name: humanities
Status: Complete
Serial: 20020821094529
Description: Branches of learning that investigate human
constructs and concerns as opposed to natural processes.
Netiquette: ftp://rtfm.mit.edu.example/pub/usenet
/news.announce.newusers
/A_Primer_on_How_to_Work_With_the_Usenet_Community
Rules: http://www.uvv.org.example/docs/howto.txt
Ctl-Send-Adr: [email protected]
Ctl-Newsgroup: news.announce.newgroup
Language: EN
Charset: US-ASCII
Encoding: text/plain
Newsgroup-Type: Discussion
Hier-Type: Global
Comp-Length: 14
Date-Create: 19950417143009
Name: humanities.answers Status: Moderated Serial: 20020821094533 Description: Repository for periodic USENET articles. (Moderated) Mod-Sub-Adr: [email protected] Mod-Adm-Adr: [email protected] Newsgroup-Type: Announce Date-Create: 19950725182040 Name: humanities.classics [...] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (IRIX64)
iD8DBQE9Zj/Wn13IYldLZg8RAhWiAJ4y7o+3FzBpRjYJj2HWwXyG2g8FoQCfeEsH rRynPhhjveiY/XBkkrrZFho=
=muK4 -----END PGP SIGNATURE----- .
<-- GETP 0 0 19990909101000 de --> 213
You are up-to-date .
<-- GETP foo --> 510 Syntax error
Missing parameters .
<-- GETP guest test 0 de --> 430
You have no permission to retrieve the data .
6.3.3.11. GETA
Description
The GETA command is used for server-server communication; it is used to collect authoritative data and will request packages that the server is authoritative for. A package is the authoritative data either for a newsgroup or a hierarchy. Each package has a "timestamp" attached to mark the revision of the package. This timestamp is set by the server to the date of the last modification of the package data in UTC format. A timestamp of "0" indicates that the package MUST be retrieved. If the retrieving client has a recent package (i.e., no modification on the authoritative server), the server sends only a 215 response. The format of the data is the same as that for the commands "HIER" and "LIST".
geta-cmd = "GETA" WSP username WSP password WSP
timestamp WSP name CRLF
Possible answers
215: The client already has the current data 430: Permission denied 411: No hierarchy with that name 510: Syntax error 615: Regular answer with all requested data
geta-answer = "615" [answertext] CRLF
pgp-ascii-armor-start ; this is according to RFC2440 *(getadata CRLF) pgp-ascii-armor-end ; this is according to RFC2440 "." CRLF
geta-answer =/ "215" [answertext] CRLF
text CRLF
"." CRLF
geta-answer =/ "430" [answertext] CRLF
text CRLF
"." CRLF
geta-answer =/ "411" [answertext] CRLF
text CRLF
"." CRLF
geta-answer =/ "510" [answertext] CRLF
text CRLF
"." CRLF
getadata = "Name:" WSP text CRLF
"Status:" WSP text CRLF
"Serial:" WSP timestamp CRLF
*(header ":" WSP text CRLF)
[("Ctl-PGP-Key:" CRLF PGP-answer/
"Mod-PGP-Key:" CRLF PGP-answer)]
Example
<-- GETA 0 0 0 humanities --> 613 data follow
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Name: humanities
Status: Complete
Serial: 20020821094529
Description: Branches of learning that investigate human
constructs and concerns as opposed to natural processes.
Netiquette: ftp://rtfm.mit.edu.example/pub/usenet
/news.announce.newusers
/A_Primer_on_How_to_Work_With_the_Usenet_Community
Rules: http://www.uvv.org.example/docs/howto.txt
Ctl-Send-Adr: [email protected]
Ctl-Newsgroup: news.announce.newgroup
Language: EN
Charset: US-ASCII
Encoding: text/plain
Newsgroup-Type: Discussion
Hier-Type: Global
Comp-Length: 14 Date-Create: 19950417143009
Name: humanities.answers Status: Moderated Serial: 20020821094533 Description: Repository for periodic USENET articles. (Moderated) Mod-Sub-Adr: [email protected] Mod-Adm-Adr: [email protected] Newsgroup-Type: Announce Date-Create: 19950725182040
Name: humanities.classics [...] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (IRIX64)
iD8DBQE9Zj/Wn13IYldLZg8RAhWiAJ4y7o+3FzBpRjYJj2HWwXyG2g8FoQCfeEsH rRynPhhjveiY/XBkkrrZFho= =muK4 -----END PGP SIGNATURE----- .
6.3.3.12. Unknown Commands and Syntax Errors
If a command is recognized as unknown, a 519 return code (unknown command) is given. If an error occurs after the command string (e.g., a missing parameter), a 510 return code (Syntax error: Missing parameter) is given.
Data Headers
The following paragraphs describe key words and key terms that support retrieval and storing of information. Every header has a unique English name.
The content of a header is inheritable within a hierarchy, as long as
the header is marked as inheritable. The content is the default value for all downstream newsgroups and sub-hierarchies. For example, in the hierarchy "de", the language header has the value "DE" (German); therefore, this value is "DE" for all newsgroups in this hierarchy, except for those that explicitly define a language code of their own.
Hierarchies and newsgroups must have at least values for the headers "Name" and "Status". Unknown hierarchies or groups get the status "Unknown".
The header used in the NAS protocol are not case sensitive. A header may be uppercase, lowercase, or any mixture of upper- and lowercase. It is recommended that the first letter of the header and the first letter after a dash be uppercase and that all other characters be lowercase.
Name
Header: Name
Used for: hierarchy Mandatory: yes Inheritable: no Repeatable: no Description: Name of a hierarchy. Comment: Start of a new data block. Example: Name: comp
Used for: newsgroup Mandatory: yes Repeatable: no Description: Name of a newsgroup Comment: Start of a new data block. Example: Name: de.admin.news.announce
Status
Header: Status
Used for: hierarchy Mandatory: yes Inheritable: no Repeatable: no Description: Status of a hierarchy. Comment: For a detailed description, see Section 6.4. Example: Status: Hierarchy-Complete
Used for: newsgroup Mandatory: yes Repeatable: no Description: Status of a newsgroup. Comment: For a detailed description, see Section 6.4. Example: Status: Group-Moderated
Serial
Header: Serial
Used for: hierarchy Mandatory: no Inheritable: no Repeatable: no Description: Timestamp for hierarchy data. Comment: For a detailed description, see Section 6.4. Example: Serial: 20020821102413
Used for: newsgroup Mandatory: no Inheritable: no Repeatable: no Description: Timestamp for newsgroup data. Comment: For a detailed description, see Section 6.4. Example: Serial: 20020821102413
Group for followup
Header: Followup
Used for: newsgroup Mandatory: no Repeatable: no Description: Name of the newsgroup that will take the followup
postings of a moderated group.
Comment: The value can be used as default value for the
"Followup-To:" header on postings to a moderated group.
This value is only useful on groups that are moderated
(Status Group-Moderated) and have a dedicated discussion
group.
Example: Followup: bln.announce.fub.zedat.d
(for the moderated group bln.announce.fub.zedat)
Short description
Header: Description
Used for: hierarchy Mandatory: no Inheritable: no Repeatable: no Description: Short description of a hierarchy. Example: Description: Angelegenheiten, die den Grossraum Berlin
betreffen
(for the hierarchy bln)
Used for: newsgroup Mandatory: no Repeatable: no Description: Short description of a newsgroup. Comment: This information is often presented to the news reader
upon selection of the newsgroup, and it should be a
brief but meaningful description of the topic.
Example: Description: Technisches zur Newssoftware
(for de.admin.news.software)
Charter-URL
Header: Charter
Used for: hierarchy Mandatory: no Inheritable: no Repeatable: yes Description: URL that points to the charter of a hierarchy. Example: Charter: ftp://ftp.fu-berlin.de.example/doc/news/bln/bln
(for the hierarchy bln)
Used for: newsgroup Mandatory: no Repeatable: yes Description: URL that points to the charter of a newsgroup. Comment: This information should be presented to the
news reader upon selection of the newsgroup.
Example: Charter: ftp://ftp.fu-berlin.de.example/doc/news/bln
/bln.markt.arbeit
Netiquette-URL
Header: Netiquette
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: URL that points to the netiquette of a hierarchy. Comment: Since the netiquettes are often valid for
a complete hierarchy, this is inheritable.
Example: Netiquette:
http://www.kirchwitz.de.example/~amk/dni/netiquette
Used for: newsgroup Mandatory: no Repeatable: yes Description: URL for Netiquette. Comment: If a group has some special rules, this is the
pointer to these rules.
Example: Netiquette: http://go.to.example/bln.markt
(for bln.markt)
Frequently Asked Questions (FAQ)
Header: FAQ
Used for: Newsgroup Mandatory: no Repeatable: yes Description: URL for the FAQ of a newsgroup. Example: FAQ: http://www.dard.de.example/
Administration rules
Header: Rules
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: URL pointing to a document that describes the rules for
creating, deleting, or renaming newsgroups in this
hierarchy.
Comment: Normally inherited from the toplevel hierarchy.
Example: Rules: http://www.kirchwitz.de.example/~amk/dai
/einrichtung
Control Email
Header: Ctl-Send-Adr
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Email address of the sender of control messages. Comment: Multiple addresses are valid. Example: Ctl-Send-Adr: [email protected]
Control newsgroup
Header: Ctl-Newsgroup
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Name of the newsgroup that will get the postings for
checkgroups, rmgroup, and newsgroup control messages.
Example: Ctl-Newsgroup: de.admin.news.groups
Moderators
Header: Mod-Wildcard
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Moderator wildcard for this hierarchy. Comment: This information can be used for the configuration of
the news software, for example, to configure the
moderators file in INN.
Example: Mod-Wildcard: %[email protected]
(for the hierarchy de)
Submission address
Header: Mod-Sub-Adr
Used for: newsgroup Mandatory: no Repeatable: yes Description: Email address for submissions to the newsgroup. Comment: If there is no "Mod-Sub-Adr" for a moderated newsgroup,
"Mod-Wildcard" of the hierarchy is used. This is useful
only for moderated groups (Status Group-Moderated).
Example: Mod-Sub-Adr: [email protected]
(for the newsgroup news.answers)
Moderator's address (email)
Header: Mod-Adm-Adr
Used for: newsgroup Mandatory: no Repeatable: yes Description: Email address of the moderator of the newsgroup. Comment: If there is no code "Mod-Adm-Adr" for a moderated
newsgroup, "Mod-Wildcard" of the hierarchy is used.
This is useful only for moderated groups
(Status Group-Moderated).
Example: Mod-Adm-Adr: [email protected]
(for the newsgroup news.answers)
Info-URL
Header: Mod-Group-Info
Used for: newsgroup Mandatory: no Repeatable: yes Description: URL that points to a document where the moderator
presents information about the newsgroup and the
submission of articles.
Example: Mod-Group-Info: http://www.example.org/cola-submit.html
(for comp.os.linux.announce)
Language
Header: Language
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: The language that will normally be used in postings. Comment: The notation is according to the "Content-Language"
field of RFC2616. The languages not preferred are enclosed in parentheses.
Example: Language: DE
(for the hierarchy de)
Used for: newsgroup Mandatory: no Repeatable: yes Description: The language that will normally be used in postings. Comment: The notation is according to the "Content-Language"
field of RFC2616. The languages not preferred are enclosed in parentheses.
Example: Language: TR
Language: DE
Language: (EN)
(for the newsgroup bln.kultur.tuerkisch)
Charset
Header: Charset
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Charset that will normally be used in postings in this
hierarchy.
Comment: The complete set of charset names is defined by
RFC2277 and the IANA Character Set registry [IANA-CS]. The charsets that are not the preferred charsets are enclosed in parentheses.
Example: Charset: ISO-8859-1
(for the hierarchy de)
Used for: newsgroup Mandatory: no Repeatable: yes Description: Charset that will normally be used in
postings in this group.
Comment: The complete set of charset names is defined by
RFC2277 and the IANA Character Set registry [IANA-CS]. The charsets that are not the preferred charsets are enclosed in parentheses.
Example: Charset: ISO-8859-9
Charset: ISO-8859-1
(for the newsgroup bln.kultur.tuerkisch)
Encoding
Header: Encoding
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Encoding for this hierarchy according to MIME RFC2045. Comment: This is the media type used in this hierarchy; a list of
registered media types can be found at [IANA-MT]. The
encodings not preferred are enclosed in parentheses.
Example: Encoding text/plain
Used for: newsgroup Mandatory: no Repeatable: yes Description: Encoding for this newsgroup according to MIME RFC2045. Comment This is the media type used in this newsgroup; a list of
registered media types can be found at [IANA-MT]. The
encodings not preferred are enclosed in parentheses.
Example: Encoding: text/plain
Type of newsgroup
Header: Newsgroup-Type
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Default newsgroup type in this hierarchy. Comment: This header has no concrete meaning for a hierarchy but
is used for the inheritance to newsgroups in the
hierarchy.
Specification of the types can be found in Section 6.5.
Example: Newsgroup-Type: Discussion
(for the hierarchy de)
Used for: newsgroup Mandatory: no Repeatable: yes Description: Type of newsgroup. Comment: Specification of the types can be found in Section 6.5. Example: Newsgroup-Type: Announce
(for de.admin.news.announce)
Type of hierarchy
Header: Hier-Type
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Type of hierarchy. Comment: Specification of the types can be found in Section 6.6. Example: Hier-Type: Regional
(for hierarchy bln)
Regional or Organizational Area
Header: Area
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: Description of the geographical region or organization
of this hierarchy.
Comment: This code is useful when the hierarchy type
(Hier-Type) is "Regional" or "Organization".
Example: Area: Grossraum Berlin
(for the hierarchy bln)
Name length of group names
Header: Name-Length
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Maximum length of a newsgroup name. Example: Name-Length: 72
(for the hierarchy bln)
Component length of group names
Header: Comp-Length
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Maximum length of a single component in the newsgroup
name.
Example: Comp-Length: 14
(for the hierarchy de)
Article length
Header: Article-Length
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Maximum length of an article in bytes. Comment: This header has no concrete meaning for a hierarchy but
is used for the inheritance to newsgroups in the
hierarchy.
Example: Article-Length: 50000
Used for: newsgroup Mandatory: no Repeatable: no Description: Maximum length of an article in bytes. Example: Article-Length: 50000
Date of creation
Header: Date-Create
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Creation date of a hierarchy; can even be in the future. Comment: The format is the same as in the DATE command. Example: Date-Create: 19970330101514
Used for: newsgroup Mandatory: no Repeatable: no Description: Creation date of a newsgroup; can even be in the future. Comment: The format is the same as in the DATE command. Example: Date-Create: 19970330101514
Date of removal
Header: Date-Delete
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Date of removal of a hierarchy; can even be in the
future.
Comment: The format is the same as in the DATE command. Example: Date-Delete: 19970330101514
Used for: newsgroup Mandatory: no Repeatable: no Description: Date of removal of a newsgroup; can even be in the
future.
Comment: The format is the same as in the DATE command. Example: Date-Delete: 19970330101514
Successor
Header: Replacement
Used for: hierarchy Mandatory: no Inheritable: no Repeatable: yes Description: Name of the hierarchy that replaced a removed hierarchy
if status is "Hierarchy-Obsolete" or will replace a
hierarchy if the date of removal is in the future.
Example: Replacement: de
(for the hierarchy sub)
Used for: newsgroup Mandatory: no Repeatable: yes Description: Name of the newsgroup or newsgroups that will replace a
removed newsgroup if status is "Group-Removed" or will
replace the newsgroup if the date of removal is in the
future.
Example: Replacement: bln.markt.arbeit
(for bln.jobs)
Source
Header: Source
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: no Description: Pointer to an organization or person responsible
for this hierarchy. SHOULD be a URL or an email
address.
Example: Source: http://www.dana.de.example/mod/
(for the hierarchy de)
E: This is for tracking the maintainer of a hierarchy.
Control PGP key
Header: Ctl-PGP-Key
Used for: hierarchy Mandatory: no Inheritable: yes Repeatable: yes Description: PGP key (with additional information: key owner, key-id,
etc.) of the sender of control messages in this
hierarchy.
Comment: The exact format is described in Section 6.7. Example: Ctl-PGP-Key:
U de.admin.news.announce
B 1024
I D3033C99
L http://www.dana.de.example/mod/pgp/dana.asc
L ftp://ftp.isc.org.example/pub/pgpcontrol/PGPKEYS.gz
F 5B B0 52 88 BF 55 19 4F 66 7D C2 AE 16 26 28 25
V 2.6.3ia
K------BEGIN PGP PUBLIC KEY BLOCK-----
K-Version: 2.6.3ia
K-
K-mQCNEALZ+Xfm/WDCEMXM48gK1PlKG6TkV3SLbXt4CnzpGM0tOMa
K-HjlHqM1wEGUHD5hw/BL/heR5Tq+C5IEyXQQmYwkrgeVFMOz/rAQ
[...]
K-SDw+iQgAAtN6zrYOhHFBp+
K-VpvRovMz+lSOy9Zcsbs+5t8Pj9ZVAQyfxBkqD5A=
K-=Xwgc
K -----END PGP PUBLIC KEY BLOCK-----
Moderator's PGP key
Header: Mod-PGP-Key
Used for: newsgroup Mandatory: no Repeatable: yes Description: Public PGP key (with additional information: key owner,
key-id, etc.) of this newsgroup's moderator.
Comment: The exact format is described in Section 6.7 Example: See Section 6.7.
Status Indicators
The status indicator uniquely determines the status of a hierarchy or newsgroup. The indicator is case insensitive.
Indicator Type Description
--------- -------------------------------------------
Complete hierarchy Authorized, complete known hierarchy Incomplete hierarchy Not completely known hierarchy (like free.*) Obsolete hierarchy Obsolete hierarchy; should contain only
newsgroups with status "Removed"
Unknown hierarchy No information available; unknown hierarchy Unmoderated newsgroup Posting allowed; unmoderated Readonly newsgroup Posting not allowed Moderated newsgroup Moderated group; articles must be sent to
the moderator
Removed newsgroup Deleted or renamed newsgroup; no posting or
transport
Unknown newsgroup Unknown group; no information available
--------- -------------------------------------------
Newsgroup Types
A Newsgroup Type is a comprehensive overview about some characteristics of a newsgroup, being a test group, a binary group, or some other kind. The Newsgroup Type is case insensitive.
Type Meaning
------------------------------------------------------
Discussion Discussion (text postings) Binary (Encoded) binary postings Sources Source postings (e.g., comp.unix.sources) Announce Announcements, press releases, RfD/CfV Test Test postings, sometimes reflectors (e.g., de.test)
Robots Automatic postings (like the former comp.mail.maps) Experiment Experimental, other
------------------------------------------------------
Hierarchy Types
To describe a hierarchy, the following Hierarchy Types are used. These Types are used to mark some properties of a news hierarchy. They are case insensitive.
Type Meaning
---------------------------------------------------
Global International, global hierarchy
(e.g., the hierarchies comp, de, rec)
Regional Regional hierarchy
(e.g., the hierarchies ba, bln, tor)
Alt Alternative hierarchy, simpler rules for
creating a group, no formal structure
(e.g., the hierarchy alt)
Non-commercial Only for personal use; commercial use is prohibited
(e.g., the hierarchy de)
Commercial Commercial use permitted (e.g., the hierarchy biz) Organization Hierarchy bound to an organization
(e.g., the hierarchy gnu)
---------------------------------------------------
PGP Keys
PGP keys for Ctrl-PGP-Key and Mod-PGP-Key are transmitted in the following structure:
PGP-answer = "V" SP Version CRLF
"U" SP User-ID CRLF
"B" SP Bits CRLF
"I" SP Key-ID CRLF
"F" SP Finger CRLF
*("L" SP Location CRLF)
*("K-" Keyblock CRLF)
"K" SP Keyblock CRLF
Version = text User-ID = text Bits = text Key-ID = text Finger = text Location = text Keyblock = text
Key Name Mandatory Description --- --------- --------- -------------------------------------- K Keyblock yes Public key block in ASCII armor format
RFC2440
V Version yes PGP-Version U User-ID no Key user id B Bits no Number of bits I Key-ID no Key id, without leading "0x" F Finger no Fingerprint L Location no URL that points to the public key --- --------- --------- --------------------------------------
A hyphen following the code indicates that the block is continued on the next line. In the last message row, there MUST be white space after the code; this is also true for a single line code.
Example
<-- HIER de --> 611 Data coming
Name: de Status: Hierarchy [...] Ctl-PGP-Key: U de.admin.news.announce B 1024 I D3033C99 L http://www.dana.de.example/mod/pgp/dana.asc L ftp://ftp.fu-berlin.de.example/unix/news/pgpcontrol/PGPKEYS.gz F 5B B0 52 88 BF 55 19 4F 66 7D C2 AE 16 26 28 25 V 2.6.3ia K------BEGIN PGP PUBLIC KEY BLOCK----- K-Version: 2.6.3ia K- K-mQCNAzGeB/YAAAEEALZ+Xfm/WDCEMXM48gK1PlKG6TkV3SLbXt4CnzpGMtOM K-HjlHaU6Xco5ijAuqM1wEGUHD5hw/BL/heR5Tq+C5IEyXQQmYwkrgeVFMO/rA [...] K-SDw+Id0JPFO9AWOiQgAAtN6zrYOhHFBp+68h9k674Yg9IHqj3BWdRjJF6PKo K-VpvRovMz+lSOy9Zcsbs+5t8Pj9ZVAQyfxBkqD5A= K-=Xwgc K -----END PGP PUBLIC KEY BLOCK----- [...]
.
Specification of the NAS Protocol (UDP)
UDP is intended for reading programs (news readers); it is not in the scope of this document. The use of UDP for NAS will be described in a separate paper.
IANA Considerations
The IANA has registered the application/nasdata media type as defined by the following information:
Media type name: application Media subtype name: nasdata Required parameters: none Optional parameters: level
The NAS protocol level number for the enclosed
NAS data package. If not present, the
protocol level defaults to 1.
Encoding scheme: NAS data is plain text; no special encodings are needed.
Security considerations: see below
Security Considerations
Security issues are only addressed in respect to server-server communication in this protocol level. Username and password combinations in the GETA and GETP commands can be used to make sure that connections are only accepted from authorized clients. PGP keys according to RFC2440 are used to sign NAS data in server-server communication in order to validate that the data is authentic and has not been tampered with.
Every server does have the possibility (in both server-server and server-client communication) to deny some commands or the whole connection according to the client's IP number.
No mechanisms are defined in the current protocol level to allow a client to validate that it is talking to a legitimate server or that the data it receives is authentic.
A stronger authentication scheme will be provided in a higher protocol level.
10. Response Codes (Overview)
Code Description
--------------------------------------------------------------
100 Command overview, Information, command description (HELP) 101 Information about connection, client and server (INFO) 200 Greeting message (Connection Setup) 201 Termination of the connection (QUIT) 202 Returns current protocol level (VERS) 213 Valid data at the client side (GETP) 215 The client already has the current data (GETA) 300 Time in UTC (DATE) 302 Answer to a successful request (VERS) 400 Indicates that the server is not giving any information (INFO) 401 Permission denied (LIST, LSTR, HIER, DATA) 402 Requested level too high; falling back to lower level (VERS) 404 Server currently out of service (Connection Setup) 410 Indicates that the server is not giving any information (HELP) 411 No hierarchy with that name (GETP, GETA) 430 Permission denied (GETP, GETA) 434 Client has no permission to talk to server (Connection Setup) 510 Syntax error 511 Internal error (TIME) 513 Line too long 519 Unknown command 610 Regular answer with all requested data (LIST, LSTR) 611 Regular answer with all requested data (HIER) 612 Regular answer with all requested data (DATA) 613 hierarchy data (GETP) 615 Regular answer with all requested data (GETA)
--------------------------------------------------------------
11. Data Headers for DATA and HIER Commands (Overview)
Header Mandatory Use Multiple Description
------------- --------- --- -------- ---------------------
Name yes H/N no Name of a hierarchy
or newsgroup (Start
of a new data block)
Status yes H/N no Status of hierarchy
or newsgroup
Serial no H/N no Revision of hierarchy
/newsgroup data
Followup no N no Group for followup
Description no H/N no Short description of
a hierarchy/newsgroup
Charter no H/N yes Charter-URL
Netiquette no H/N yes Netiquette-URL
FAQ no N yes FAQ-URL
Rules no H yes Administration rules
URL
Ctl-Send-Adr no H yes Control email
Ctl-Newsgroup no H yes Control newsgroup
Mod-Wildcard no H no Moderator wildcard
Mod-Sub-Adr no N no Submission address
Mod-Adm-Adr no N yes Moderator's address
(email)
Mod-Group-Info no N yes Info-URL
Language no H/N yes Language
Charset no H/N yes Charset
Encoding no H/N yes Encoding
Newsgroup-Type no H/N yes Type of newsgroup
Hier-Type no H yes Type of hierarchy
Area no H yes Regional or
organizational area
Name-Length no H no Total length of group
names
Comp-Length no H no Component length of
group names
Article-Length no H no Article length
Date-Create no H/N no Date of creation
Date-Delete no H/N no Date of removal
Replacement no H/N yes Successor
Source no H yes Source of data
Ctl-PGP-Key no H yes Control PGP key
Mod-PGP-Key no N yes Moderator's PGP key
------------- --------- --- -------- ---------------------
N: Newsgroup, H: Hierarchy
12. References
12.1. Normative References
[IANA-CS] IANA: Character Sets,
<http://www.iana.org/assignments/character-sets>.
RFC2045 Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
RFC2119 Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
RFC2277 Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, January 1998.
RFC2440 Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,
"OpenPGP Message Format", RFC 2440, November 1998.
RFC2616 Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
L., Leach, P., and T. Berners-Lee, "Hypertext Transfer
Protocol -- HTTP/1.1", RFC 2616, June 1999.
RFC4234 Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
12.2. Informative References
[IANA-MT] IANA: Media Types, <http://www.iana.org/assignments/>.
[IANA-PN] IANA: Assigned Port Numbers,
<http://www.iana.org/assignments/port-numbers>.
RFC1305 Mills, D., "Network Time Protocol", RFC 1305, University of
Delaware, March 1992.
[SON1036] H. Spencer, "News Article Format and Transmission", A Draft
for an RFC 1036 Successor, <ftp://zoo.toronto.edu/pub/news.txt.Z>.
[USEFOR] USEFOR Working Group, "News Article Format", Work in
Progress.
Acknowledgement
This work has been supported by the German Academic Network Organization (DFN-Verein) with funds from the German Federal Ministry of Education and Research (Bundesministerium fuer Bildung und Forschung).
Authors' Addresses
Philipp Grau Vera Heinau Heiko Schlichting Robert Schuettler
Freie Universitaet Berlin ZEDAT Fabeckstr. 32 14195 Berlin Germany
Phone: +49 30 838-74707 Fax: +49 30 838-56721
EMail: [email protected] URL: http://nas.fu-berlin.de/
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