News Servers: INN

The InterNetNews (INN) news server accesses Usenet newsfeeds, providing news clients on your network with the full range of newsgroups and their articles. Newsgroup articles are transferred using NNTP, and servers that support this protocol are known as NNTP servers. INN was written by Rich Salz and is currently maintained and supported by the Internet Software Consortium (ISC). You can download current versions from its Web site at www.isc.org. INN is also included with most Linux distributions. The documentation directory for INN in /usr/share/doc contains extensive samples. The primary program for INN is the innd daemon.

INN Configuration Files

Various INN configuration files can be found in /etc/news, including inn.conf, storage.conf, readers.conf, and incoming.conf (see Table 26-1). inn.conf sets options for INN, and the incoming.conf file holds the hosts from which you receive newsfeeds. Place entries for remote hosts in the readers.conf file to allow them access to your news server. Actual newsfeeds are managed in directories in the /var/spool/news directory. Here you will find directories such as article, which holds newsgroup articles; outgoing for articles being posted by your users to newsgroups; and overview, which holds summary information about articles. Correct configuration of INN can be a complex and time-consuming process, so be sure to consult references and online resources, such as the documents. When you change configurations, be sure to restart the INN server. An innd script is in the /etc/rc.d/init.d directory, which has similar arguments to the Web httpd script. You can use start, restart, and stop arguments with the innd script to start, restart, and stop the INN server.

Table 26-1: INN Configuration Files
File	Description
inn.conf	General INN configuration file.
incoming.conf	Specifies hosts from which newsfeeds are received.
cycbuff.conf	Configures buffers used in cnfs storage format.
storage.conf	Defines storage classes. These consist of a storage method and the newsgroups that use it. Storage methods are the storage formats: tradspool, timehash, timecaf, and cnfs. An additional method, trash, throws out the articles.
expire.ctl	Sets the expiration policy for articles on the news server.
readers.conf	Designates hosts whose users can access the news server with newsreaders.
ovdb.conf	Configures ovdb storage method for overviews.
newsfeeds	Defines how your news server feeds articles to other news servers.
moderated	Moderated newsgroups.
innfeed.conf	Configures newsfeed processes for innfeed.
innreport.conf	Configures innreport utility for generating log-based reports.
buffindexed.conf	Configures overview buffer for buffindexed method.

Tip

There is a man page for each configuration file in INN, providing detailed information on how to configure their features.

inn.conf

On many distributions, a basic inn.conf file is already set up for you with default settings. Several of the initial parameters you will have to set yourself, such as domain, which holds the domain name for your server; pathhost, in which you specify the name for your newsreader as you want it to appear in the Path header field for news articles you post; and server, in which you specify your newsreader's IP or fully qualified domain name address, as in mynews.mytrek.com. Different Path options have already been set up for you defining the location of different INN directories, such as patharticles set to /var/spool/news articles that holds your newsgroup articles, and pathetc set to /etc/news for your configuration files.

Storage Formats

Storage formats for the vast number of news articles that are often downloaded and accessed are a central concern for a full-scale news server like INN. INN lets you choose among four possible storage formats: tradspool, timehash, timecaf, and cnfs. tradspool is the traditional method whereby articles are arranged in a simple directory structure according to their newsgroups. This is known to be very time-consuming to access and store. timehash stores articles in directories organized by the time they were received, making it easier to remove outdated articles. timecaf is similar to timehash, but articles received at a given time are placed in the same file, making access much faster. cnfs stores articles into buffer files that have already been set up. When a buffer file becomes full, the older articles are overwritten by new ones as they come in. This is an extremely fast method, since no new files are created. There is no need to set maximum article limits, but there is also no control on how long an article is retained. In the storage.conf file, storage formats are assigned as storage methods to different newsgroups.

Overviews

INN also supports overviews. These are summaries of articles that readers can check, instead of having to download the entire article to see what it is. Overviews have their own storage methods: tradindexed, buffindexed, and ovdb. You specify the one you want to use in the ovmethod feature in inn.conf. tradindexed is fast for readers, but difficult for the server to generate. buffindexed is fast for news servers, but slow for readers. ovdb uses Berkeley DB database files and is very fast for both, but uses more disk space. If you choose ovdb, you can set configuration parameters for it in ovdb.conf.

INN Implementation

On many distributions, a news user is already created with a newsgroup for use by your INN daemon and sets up the news directories in /var/spool/news. INN software also installs cron scripts, which are used to update your news server, removing old articles and fetching new ones. These are usually placed in the /etc/cron.daily directory, though they may reside anywhere. inn-cron-expire removes old articles, and inn-cron-rnews retrieves new ones. inn-cron-nntpsend sends articles posted from your system to other news servers.

INN also includes several support programs to provide maintenance and crash recovery, and to perform statistical analysis on server performance and usage. cleanfeed implements spam protection, and innreport generates INN reports based on logs. INN also features a very strong filter system for screening unwanted articles.

Note

Leafnode is an NNTP news server designed for small networks that may have slow connections to the Internet. You can obtain the Leafnode software package along with documentation from its Web site at www.leafnode.org. Along with the Leafnode NNTP server, the software package includes several utilities such as Fetchnews, Texpire, and Newsq that send, delete, and display news articles. slrnpull is a simple single-user version of Leafnode that can be used only with the slrn newsreader.