JPL's Wireless Communication Reference Website Help


Instructions for Multiple-User Set-up

A special welcome file for on-line access is available. It directs local users to the material and informs external visitors about where to see a demo. version.

System administrators are welcome to edit this page to their own needs, for instance to change the hyperlinks for local user to the URL location of the CD Rom contents, or include a link returning to the home page of their organization.

Experiences at Berkeley

One of the first institutions to provide Wireless Communications on-line was the EECS Department at U.C. Berkeley. They choose to have the files stored on hard disk, instead of having a CD ROM player stand by continuously. Thanks to Jenni Snider and Kevin Mullally, the Wireless Communications home page is working as described below. Here is a report of their set-up

"... There is nothing special about the technique we used to restrict access. Any WWW sys admin could do it, but each site will require some time for testing within their own environment."

Anyone can access the first page as: 

	http://www-inst.eecs.berkeley.edu/~wireless
That is, any file in the ~wireless/public_html directory can be read by the world. The WWW server automatically converts the above request into 
	http://www-inst.eecs.berkeley.edu/~wireless/public_html/welcome.htm
From this welcome page, the EECS user can access pages in the subdirectory ~wireless/public_html/eecs_only. Here files can be read only from computers on EECS and CS subnets.

In all cases, the files and directories must be world-readble for the httpd server to display them at all. To made files and directories world-readable, use the commands: 

for a file:		chmod ugo+r filen ame
for a directory:	chmod ugo+rx directoryn ame
The "ugo" part means "user, group, other". These permissions have been set on all the files under ~wireless/public_html.

Note: The URL is in fact http://www-inst.eecs.berkeley.edu/~ee290i instead of . http://www-inst.eecs.berkeley.edu/~wireless. EE290i is the catalogue number of the wireless course.

HTTP server

The berkeley http server has an access configuration file, in which an entire directory can be restricted for access by specific subnets only. Since you'd like the top level wireless home page to be world readable, they have created a subdirectory called ~wireless/public_html/eecs_only. The eecs_only directory will be entered into the access config file for access from the "cs" and "eecs" nets only. To test he set-up they copied just one file to eecs_only; when restricted access appeared to work, all files except the index.html file wre copied into the directory. They have changed the permissions of 
	~wireless/public_html
	~wireless/public_html/index.htm
	~wireless/public_html/eecs_only
	~wireless/public_html/eecs_only/welcome.htm
to be world-readble. Everything else is NOT world readable so nobody can access those files via the WWW.

They found that in order for changes to our server configuration to take effect immediately on our HP system, they had to kill ALL processes that the server had started and then restart the server, rather than just restarting the single server process. That was the only caveat.

Berkeley uses the public domain http server from NCSA, available via anonymous ftp (no password required) from ftp.ncsa.uiuc.edu and also through http://hoohoo.ncsa.uiuc.edu.

To restrict access for certain directories within the file space that the httpd server can read, the file conf/access.conf is modified. Here is an excerpt from that file, showing the lines that limit access to the ~wireless/public_html/eecs_only directory to EECS and CS subnets only: 

  #=====================================================================
  # NCSA HTTPd (comments, questions to httpd@ncsa.uiuc.edu)
  #=====================================================================
  # This is the gloabal access configuration file.
  # Documentation for NCSA HTTPd is available from
  # http://hoohoo.ncsa.uiuc.edu/
  # Documentation specific to this file is at
  # http://hoohoo.ncsa.uiuc.edu/docs/setup/access/Overview.html
  # http://hoohoo.ncsa.uiuc.edu/docs/tutorials/user.html
  #
  # NCSA takes no responsibilty for any problems that result from the use
  # of this server.  See the COPYRIGHT statement that came with this
  # distribution.
  #=====================================================================
  
  ### .... some data omitted for brevity ...
  
  <Directory /home/n/wireless/public_html/eecs_only>
  Options Indexes FollowSymLinks
  AllowOverride All
  <Limit GET>
  order deny,allow
  deny from all
  allow from cs eecs
  </Limit>
  </Directory>
Other sys admins will need to be sure this correct for whatever httpd they might be using. Older servers may not support this feature.

Thanks to Kevin Mullally
Manager, EECS Instructional Support


JPL's Wireless Communication Reference Website © Jean-Paul M.G. Linnartz, 1993, 1995.