For the rsh invocation to work properly, each user who posts news must have an equivalent account on the server system, i.e., one to which she can log in without being asked for a password.
Make sure that the hostname given in server literally matches the output of the hostname command on the server machine, or else C News will loop forever in an attempt to deliver the article. We discuss NFS is detail in Chapter 14, The Network File System.
Maintenance Tools and Tasks
Despite the complexity of C News, a news administrator's life can be fairly easy; C News provides you with a wide variety of maintenance tools. Some of these are intended to be run regularly from cron, like newsdaily. Using these scripts greatly reduces daily care and feeding requirements of your C News installation.
Unless stated otherwise, these commands are located in /usr/lib/news/maint. (Note that you must become user news before invoking these commands. Running them as a superuser may render critical newsfiles inaccessible to C News.):
newsdaily
The name already says it: run this once a day. It is an important script that helps you keep log files small, retaining copies of each from the last three runs. It also tries to sense anomalies, like stale batches in the incoming and outgoing directories, postings to unknown or moderated newsgroups, etc. Resulting error messages are mailed to the newsmaster.
newswatch
This script should be run regularly to look for anomalies in the news system, once an hour or so. It is intended to detect problems that will have an immediate effect on the operability of your news system, in which case it mails a trouble report to the newsmaster. Things checked include stale lock files that don't get removed, unattended input batches, and disk space shortage.
addgroup
This script adds a group to your site locally. The proper invocation is:
addgroup groupname y|n|m|=realgroup
The second argument has the same meaning as the flag in the active file, meaning that anyone may post to the group (y), that no one may post (n), that it is moderated (m), or that it is an alias for another group (=realgroup). You might also want to use addgroup when the first articles in a newly created group arrive earlier than the newgroup control message that is intended to create it.
delgroup
This script allows you to delete a group locally. Invoke it as:
delgroup groupname
You still have to delete the articles that remain in the newsgroup's spool directory. Alternatively, you might leave it to the natural course of events (i.e., expiration) to make them go away.
addmissing
This script adds missing articles to the history file. Run it when there are articles that seem to hang around forever.
newsboot
This script should be run at system boot time. It removes any lock files left over when news processes were killed at shutdown, and closes and executes any batches left over from NNTP connections that were terminated when shutting down the system.
newsrunning
This script resides in /usr/lib/news/input and may be used to disable unbatching of incoming news, for instance during work hours. You may turn off unbatching by invoking:
/usr/lib/news/input/newsrunning off
It is turned on by using on instead of off.
Chapter 22. NNTP and the nntpd Daemon
Network News Transfer Protocol (NNTP) provides for a vastly different approach to news exchange from C News and other news servers without native NNTP support. Rather than rely on a batch technology like UUCP to transfer news articles between machines, it allows articles to be exchanged via an interactive network connection. NNTP is not a particular software package, but an Internet standard described in RFC-977. It is based on a stream-oriented connection, usually over TCP, between a client anywhere in the network and a server on a host that keeps Netnews on disk storage. The stream connection allows the client and server to interactively negotiate article transfer with nearly no turnaround delay, thus keeping the number of duplicate articles low. Together with the Internet's high-transfer rates, this adds up to a news transport that surpasses the original UUCP networks by far. While some years ago it was not uncommon for an article to take two weeks or more before it arrived in the last corner of Usenet; it is now often less than two days. On the Internet itself, it is even within the range of minutes.
Various commands allow clients to retrieve, send, and post articles. The difference between sending and posting is that the latter may involve articles with incomplete header information; it generally means that the user has just written the article.[132] Article retrieval may be used by news transfer clients as well as newsreaders. This makes NNTP an excellent tool for providing news access to many clients on a local network without going through the contortions that are necessary when using NFS.
NNTP also provides for an active and a passive way to transfer news, colloquially called "pushing" and "pulling." Pushing is basically the same as the ihave/sendme protocol used by C News (described in Chapter 21, C News). The client offers an article to the server through the IHAVE msgid command, and the server returns a response code that indicates whether it already has the article or if it wants it. If the server wants the article, the client sends the article, terminated by a single dot on a separate line.
Pushing news has the single disadvantage that it places a heavy load on the server system, since the system has to search its history database for every single article.
The opposite technique is pulling news, in which the client requests a list of all (available) articles from a group that have arrived after a specified date. This query is performed by the NEWNEWS command. From the returned list of message IDs, the client selects those articles it does not yet have, using the ARTICLE command for each of them in turn.
Pulling news needs tight control by the server over which groups and distributions it allows a client to request. For example, it has to make sure that no confidential material from newsgroups local to the site is sent to unauthorized clients.
There are also a number of convenience commands for newsreaders that permit them to retrieve the article header and body separately, or even single header lines from a range of articles. This lets you keep all news on a central host, with all users on the (presumably local) network using NNTP-based client programs for reading and posting. This is an alternative to exporting the news directories via NFS, as described in Chapter 21.
An overall problem of NNTP is that it allows a knowledgeable person to insert articles into the news stream with false sender specification. This is called news faking or spoofing.[133] An extension to NNTP allows you to require user authentication for certain commands, providing some measure of protection against people abusing your news server in this way.
132
When posting an article over NNTP, the server always adds at least one header field, NNTP-Posting-Host:. The field contains the client's hostname.
133
The same problem exists with the Simple Mail Transfer Protocol (SMTP), although most mail transport agents now provide mechanisms to prevent spoofing.