Access to NNTP resources is governed by the file nntp_access in /usr/lib/news . Lines in the file describe the access rights granted to foreign hosts. Each line has the following format:
If a client connects to the NNTP port, nntpd attempts to obtain the host's fully qualified domain name from its IP address by reverse lookup. The client's hostname and IP address are checked against the site field of each entry in the order in which they appear in the file. Matches may be either partial or exact. If an entry matches exactly, it applies; if the match is partial, it only applies if there is no other match following which is at least as good. site may be specified in one of the following ways:
Entries with a more general site specification should be specified earlier, because any matches by these will be overridden by later, more exact matches.
The second and third field describe the access rights granted to the client. The second details the permissions to retrieve news by pulling (read), and transmit news by pushing (xfer). A value of both enables both, no denies access altogether. The third field grants the client the right to post articles, that is, deliver articles with incomplete header information which is completed by the news software. If the second field contains no, the third field is ignored.
The fourth field is optional, and contains a comma-separated list of groups the client is denied access to.
A sample nntp_access file is shown below: