UNIX System Administration Handbook - Evi Nemeth [414]
Since HP-UX uses /etc/logingroup instead of /etc/group, you must put a copy of the logingroup file in the ~ftp/etc directory.
Both FreeBSD and Red Hat use shared libraries, but everything you need is automatically installed in ~ftp during the OS installation process. In fact, anonymous FTP is turned on by default. Although the default configuration makes anonymous FTP setup easy, it does pose a risk to the unsuspecting system administrator who is unaware of its presence. Remove the ftp user from the passwd file if you do not wish to provide anonymous FTP service. Under FreeBSD, you must be sure to compile the passwd file to ~ftp/etc/pwd.db by running the pwd_mkdb command; see the man page for details.
22.7 USENET NEWS
Usenet news is a software system that originated in the 1970s to distribute short messages (“articles”) to sites around the world. It is not really a type of network, but rather a set of protocols, file formats, and affiliations among sites. Usenet is made up of a large number of “newsgroups,” which are similar to the message boards hosted by some web sites and on-line services. These days, Usenet has in many ways been supplanted by the World Wide Web. Many ISPs don’t even bother to offer it as a service anymore, and new users often don’t discover it.
Usenet uses a “flood fill” method of delivery. There is no central site from which content originates.5
Instead, when a user creates (“posts”) a new article, it is sent to the news server of the ISP for that user. The ISP’s server offers the article to the other sites with which it exchanges articles. Each time an article reaches a new server, that server offers it to any other servers with which it has a peer relationship. A path list in the article helps to prevent servers from offering articles to a sites through which they have already passed.
At the time of this writing, a full Usenet feed with no filtering (spam or article size) contains new articles in excess of 100 GB/day. The daily volume has increased fivefold in just the past year and a half, but the article count has only increased by 50% over the same period.
The bulk of Usenet traffic consists of music and video files in MPEG format and pirated software (often referred to as “warez”). In the past, most of the volume consisted of pornographic pictures. Whether or not this is progress is subject to debate, but either way, Usenet has earned the well-deserved moniker “gigabytes of copyright violations.”
With article sizes limited to 1MB and with spam and misspelled group name6
filtering, the daily traffic volume goes down to a more manageable 35 GB/day. This is still a staggering amount of data and, in general, only large ISPs have the resources (bandwidth and disk storage) or desire to handle it.7
Several alternate schemes have been devised to deliver news to sites that lack the resources to handle a full feed.
Usenet news feeds
The simplest way to obtain a news feed is to retain the services of a company, such as www.supernews.com or www.giganews.com, that specializes in hosting Usenet. In general, you just point your users’ browsers to the outsourcing provider’s news server. This option takes news administration completely off your plate.
Another option, if your upstream service provider offers it, is to get a “pull” feed. With a pull feed, your server fetches articles from another server only on demand. It also caches articles locally so that popular articles do not have to be refetched.
The advantages of using a pull feed over outsourcing news to a third party are that articles are transmitted from the remote server only once (saving bandwidth) and that since the server is local to your organization, access may feel “faster” to your users. The chief disadvantage of a demand-based pull feed is the delay between the time at which the remote server gets an article and the time at which your local server