The web proxy/cache server is actually a part of the Web Server, but it acts like a separate entity, so you can configure it separately.
A proxy server is a program that accepts connections on one port, and immediately forwards them to another server on another port. Proxy servers are frequently used to forward specific services through firewalls, or to allow access to services using special protocols that your client software doesn't understand.
A cache server is a special kind of proxy server that sometimes decides not to forward the request on to the target server. If it has recently fulfilled the same request, the result is cached on the proxy server's local hard drive so it can be retrieved more quickly in the future.
Your NetWinder can act as a simple proxy server, or as a proxy/cache server, depending on its configuration options. To use the NetWinder as a proxy or cache server, you need to configure your web browser (usually Netscape or Internet Explorer) to point at your NetWinder, port 80. You can usually do this in your browser's Options or Preferences window, under the keyword Proxy or Security.
When you click the Configure button next to Web Proxy/Cache on the NetWinder's Services screen, you will see this page:
It contains the following options. In most cases, you are safe to leave the default settings for these options.
Allow connect on ports. Allow browsers to connect on ports other than 80 (HTTP). Usually you will want to include 443 (HTTPS), 563 (SNEWS), and 8080 (alternative HTTP).
Cache default expiration. This is the default amount of time to keep a document in the cache if the document's owner hasn't specified this value. If a document is requested again within this time limit, it will be retrieved from the cache instead of from the original server This value is in hours.
Cache directory length. This is the number of characters in cache storage directory names, usually 2.
Cache directory levels. This is the number of 'levels' in the cache storage directories, usually 4.
Force completion to cache. If a web browser cancels a request in progress, the NetWinder can attempt to finish retrieving the document from the original server to be stored in the cache. For example, if Cache force completion is 90, then the NetWinder will finish retrieving the document if it has already retrieved 90% or more of the file.
Cache garbage collection interval. Your NetWinder will delete entries from the cache periodically to keep the cache directory at a reasonable size. This takes place every GC interval hours, usually 1 hour.
Cache last modified factor. If a retrieved document doesn't specify an expiry time, but does include a last-modified time (which is the most common situation), the NetWinder will set the expiry time to Last-modified-factor * time-since-last-modification.
Cache maximum expiration. This is the longest possible time, in hours, that your NetWinder will keep a document in its cache without double-checking that it hasn't been changed on the original server.
Cache root. This is the directory in which to store files for the web cache. It is almost always /var/cache.
Cache size (KB). This is the maximum size, in megabytes, of the web cache. If the cache grows larger than this, your NetWinder will start throwing out old entries, so they will need to be retrieved from their original server if they are requested again.
No cache. This is a list of keywords or hosts that will not be cached by the server. If you have web servers on your local network, you should enter their names here, because it doesn't gain you anything to cache them. You gain the most benefit from caching files from the internet, so that you don't have to download them over and over again.
Proxy default domain.If a user requests a file from a hostname without a domain qualifier (e.g. server1 instead of server1.rebel.com), then the NetWinder will append Proxy domain to the name to make it complete. In this case, for example, Proxy domain should be set to rebel.com.
Proxy receive buffer size. This changes the block size for communicating with remote servers. Usually it is set to 2048.
Allow proxy requests. If this is set to Off, your NetWinder will not act as a cache or a proxy server.
Proxy via. If this is set to On, your NetWinder will include a Via: header with each request to a remote server, mentioning that the request has passed through a proxy server. For increased privacy, you can choose Off here.
Click the Save button when you've finished filling in the above values.