NNTP, Network News Transfer Protocol

Protocol suite:	TCP/IP.
Protocol type:	Application layer news protocol.
Ports:	119 (TCP). 563 (TCP) over TLS.
URI:	nntp:
MIME subtype:
SNMP MIBs:
Working groups:	nntp, Network News Transport Protocol. nntpext, NNTP Extensions.
Links:

RFC 977:

NNTP specifies a protocol for the distribution, inquiry, retrieval, and posting of news articles using a reliable stream-based transmission of news among the ARPA-Internet community. NNTP is designed so that news articles are stored in a central database allowing a subscriber to select only those items he wishes to read. Indexing, cross-referencing, and expiration of aged messages are also provided.

MAC header

IP header

TCP header

NNTP packet

NNTP commands:

Command	References
ARTICLE	RFC 977
AUTHINFO	RFC 2980
CHECK	RFC 2980
DATE	RFC 2980
GROUP	RFC 977
HELP	RFC 977
IHAVE	RFC 977
LAST	RFC 977
LIST	RFC 977, RFC 2980
LISTGROUP	RFC 2980
MODE READER	RFC 2980
MODE STREAM	RFC 2980
NEWGROUPS	RFC 977
NEWNEWS	RFC 977
NEXT	RFC 977
POST	RFC 977
QUIT	RFC 977
SLAVE	RFC 977
TAKETHIS	RFC 2980
XGTITLE	RFC 2980
XHDR	RFC 2980
XINDEX	RFC 2980
XOVER	RFC 2980
XPAT	RFC 2980
XPATH	RFC 2980
XREPLIC	RFC 2980
XROVER	RFC 2980
XTHREAD	RFC 2980

NNTP reply code categories:

Code	Description
1yz	Informative message.
2yz	Command ok.
3yz	Command ok so far, send the rest of it.
4yz	Command was correct, but couldn't be performed for some reason.
5yz	Command unimplemented, or incorrect, or a serious program error occurred.
x0z	Connection, setup, and miscellaneous messages.
x1z	Newsgroup selection.
x2z	Article selection.
x3z	Distribution functions.
x4z	Posting.
x8z	Nonstandard (private implementation) extensions.
x9z	Debugging output.

NNTP reply codes:

Code	Description
100	Help text follows.
199	Debug output.
200	Server ready - posting allowed.
201	Server ready - no posting allowed.
202	Slave status noted.
205	Closing connection - goodbye!
211	n f l s group selected.
215	List of newsgroups follows.
220	n <a> article retrieved - head and body follow 221 n <a> article retrieved - head follows.
222	n <a> article retrieved - body follows.
223	n <a> article retrieved - request text separately 230 list of new articles by message-id follows.
231	List of new newsgroups follows.
235	Article transferred ok.
240	Article posted ok.
335	Send article to be transferred. End with <CR-LF>.<CR-LF>.
340	Send article to be posted. End with <CR-LF>.<CR-LF>.
400	Service discontinued.
411	No such news group.
412	No newsgroup has been selected.
420	No current article has been selected.
421	No next article in this group.
422	No previous article in this group.
423	No such article number in this group.
430	No such article found.
435	Article not wanted - do not send it.
436	Transfer failed - try again later.
437	Article rejected - do not try again.
440	Posting not allowed.
441	Posting failed.
500	Command not recognized.
501	Command syntax error.
502	Access restriction or permission denied.
503	Program fault - command not performed.