NCSA httpd

NCSA httpd is a HTTP/1.0 compatible server for making hypertext and other
documents available to Web browsers. Please read this copyright notice. 

This code is in the public domain. Specifically, we give to the public domain all
rights for future licensing of the source code, all resale rights, and all publishing
rights. 

We ask, but do not require, that the following message be included in all derived
works: 

Portions developed at the National Center for Supercomputing Applications at the
University of Illinois at Urbana-Champaign. 

The current version is 1.3. If you are using an earlier version, the upgrade notes will
be helpful. We also have an FAQ on NCSA httpd.



Why NCSA httpd?

Here is a list of the server's features. Follow the links to read about them and see
demonstrations of their use. 

   Low Impact

      Designed to be a small, fast server. 

      Has a low impact on system resources, allowing it to serve documents
      to a large number of users simultaneously with little slowdown. With
      the amount of traffic www.ncsa.uiuc.edu gets, this was
      required. 

      Runs standalone, for faster performance, or under inetd. 

   Compatibility

   NCSA httpd speaks both the HTTP/1.0 and HTTP/0.9 protocols, and will
   serve documents to World Wide Web browsers speaking either dialect. In
   addition, NCSA httpd allows easy serving of multimedia documents through
   both protocols. 

   Unified Directory Structure

   NCSA httpd allows you to serve your documents from a single directory,
   which can be any physical directory. The World Wide Web browsers never
   see the name of this physical directory, allowing you to move your documents
   into different directories (or to a larger disk) without rewriting your HTML
   documents and telling everyone who may be using your server about the
   move. 

   In addition, if heavily publicized documents move from your server to a
   different one, NCSA httpd allows you to easily point the users to the new
   location of the documents. With some browsers, the user will not even notice
   the change. 

   Directory Indexing

   NCSA httpd allows you to create HTML catalogs of your directories, in order
   to tell users what's in them. 

   For instance, on hoohoo, I have a directory containing some neat pictures, and
   I've written a small index for it.

   I have another directory whose contents are constantly changing. I don't really
   want to write and maintain an index. In this case, httpd will generate an index
   of the directory for me when a user requests the directory. I can configure
   httpd to ignore certain files, to give a certain icon for certain files, to place a
   short description after file names, and include either an HTML or plaintext
   README which tells people what is in the directory.

   User Supported Directories

   NCSA httpd allows you to let users make their own directories available for
   HTTP access, without your having to create links to them. Of course, you can
   limit what the users can do from their directories for security reasons. 

   Server Scripts

   NCSA httpd allows you to write server scripts, which are executable
   programs which the server runs to generate documents on the fly. They are
   easy to write and can be written in your favorite language, whether it be C,
   PERL, or even the Bourne shell. 

   These scripts can be used for a number of purposes. 

      HTML forms 

      If you are using a browser which supports HTML forms, like Mosaic
      2.0 for X, you can create scripts to handle form requests. 

      For example, let's order a sub. 

      If you are familiar with the PH system, you can look a person up in the
      phone book. Try looking up Rob McCool by name. 

      Simple HTML indexes 

      Most browsers support the HTML <ISINDEX> flag. You can use
      server scripts to respond to them. 

      For example, what is hoohoo's load average right now? 

      Let's try a simple finger gateway. Try looking for robm@void, you
      may find a link.

      How about looking something up in archie? 

      Image mapping 

      If you are using a browser which supports it, you've probably noticed
      that image mapping is a fun feature. NCSA httpd lets you create your
      own maps. 

   Security

   NCSA httpd allows you to control who can access different document trees on
   your server. It also allows you to define which server functions are carried out
   in different document trees. 

   Note that the following methods of access limitation can work independently,
   or be combined. 

      Host Filtering 

      Host filtering is used to limit document trees to certain machines,
      most likely local machines or those directly involved in a project. 

      For example, I have some documents which are NCSA only. If you are
      not from a machine in ncsa.uiuc.edu, you can't access them. 

      I have another directory that I don't want NCSA people to read, since
      they can access it elsewhere. 

      User Authentication 

      If your browsers are using a browser that supports user authentication,
      like Mosaic 2.0 for X, you can have browsers authenticate themselves
      with a user name and a password before they are able to access
      protected documents. 

      For an example, let's create three users. 
         robm password pinhead 
         marca password conehead 
         ebina password bonehead 

      I have protected this directory so that only robm can access it. 

      I have protected this directory so that only people in the Mosaic X
      developers group can access it. That means ebina and marca. 

      I have protected this directory so that only robm can access it, and
      only from void.ncsa.uiuc.edu. 

   Server Side Includes

   NCSA httpd allows you to include the output of commands or other files in
   your HTML documents. 

   For instance, the current date is . 

   At the end of each document, I'd like to include my signature but don't want
   to have to change every document I wrote when my home document moves.
   So, I can use a server include tag to include it, like this: 



