Running Servers Locally

Accessing certain servers on the Internet at large is common, but running equivalents on your local network, or even on a workstation, can improve performance in some cases. Examples of servers you might want to run locally include:

Web Proxy Servers A proxy server is a stand-in for another server; it accepts requests for data transfers, processes them partially, and passes them on to other systems. Proxy servers exist for many reasons, including security, filtering unwanted content, and improving speed. Speed improvements in web proxy servers derive from two factors. First, proxy servers can cache access requests, speeding up second and subsequent requests for a document. The Squid proxy server (http://www.squid-cache.org) exists largely for this reason. Second, a proxy that filters content can remove large images that can take a long time to download. Proxies designed to remove ads, such as Privoxy (http://www.privoxy.org), have this effect.

DNS Servers Running your own DNS server can speed up DNS accesses for much the same reason that running a caching web proxy server can speed accesses. Chapter 27 covers DNS server configuration.

Mail Servers If you receive lots of e-mail from an ISP's mail server, you may wait for it to download into your mail reader. You can use a local mail server in conjunction with Fetchmail (http://catb.org/~esr/fetchmail/) to speed up local mail accesses. Fetchmail can periodically retrieve mail and store it locally, so that you don't need to wait so long when you load up your mail reader. The downside is that you won't see any mail that's arrived at your ISP between Fetchmail's last run and the time you launch your mail reader. Chapter 25, "Delivering E-Mail," covers both mail server and Fetchmail configuration.

News Servers If you read Usenet news, you can run a local news server that does for news what the combination of Fetchmail and a local mail server does for e-mail. An example of such a program is Leafnode (http://www.leafnode.org). News servers designed for this purpose are much smaller than full-blown news servers. In some configurations, the local news server may download much more data than you'll ever read, but it will do so quickly, so the total time you're connected to the news server can be much shorter than it might otherwise be. This approach is most appealing if you're charged by the minute for your Internet connect time.

Warning As described in Chapter 18, "System Security," running servers unnecessarily is a security risk. You should balance the benefits gained from running servers locally against the potential damage they might do. In some cases, the risk is very low. For instance, a server run behind a Network

Address Translation (NAT) firewall is unlikely to be found and abused by an outside miscreant. If the system on which you run a server is directly exposed to the Internet, though, the risk of running such a server is much greater.

Team LiB

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