The NNTP Protocol

Before you write your own news client, you should have some idea of how the NNTP protocol works. Like other servers, an NNTP server is bound to a port (usually port 119). It listens for incoming connections, takes the appropriate action, and returns a response to the client. When a news client connects with an NNTP server, or to the port on which the NNTP server is running, a message such as the following is produced:

Trying 0.0.0.0...
Connected to hostname.mydomain.com.
Escape character is '^]'.
200 newshost.mydomain.com InterNetNews NNRP server INN 1.5.1 17-Dec-1996 ready
(posting ok).

Many NNTP servers understand the help (or HELP) command. When a client issues a help command, many NNTP servers respond with a list of all available commands. For example:

200 news.mydomain.com InterNetNews NNRP server INN 1.5.1 17-Dec-1996 ready
(posting ok).
HELP
100 Legal commands
  authinfo user Name|pass Password|generic <prog> <args>
  article [MessageID|Number]
  body [MessageID|Number]
  date
  group newsgroup
  head [MessageID|Number]
  help
  ihave
  last
  list [active|active.times|newsgroups|distributions|distrib.pats|
overview.fmt|subscriptions]
  listgroup newsgroup
  mode reader
  newgroups yymmdd hhmmss ["GMT"] [<distributions>]
  newnews newsgroups yymmdd hhmmss ["GMT"] [<distributions>]
  next
  post
  slave
  stat [MessageID|Number]
  xgtitle [group_pattern]
  xhdr header [range|MessageID]
  xover [range] xpat header range|MessageID pat [morepat...] xpath MessageID Report problems to <usenet@news.mydomain.com> ...

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