SOCKS access for MS-Windows Mosaic

Background

Thus, this can be used to provide proxied Internet access to Win-Mosaic clients that cannot themselves connect directly to Internet resources, because they are inside an Internet Firewall.

This can be got working in two ways:

1. You may run a proxying daemon (such as CERN's httpd 2.17beta) on a system which does have direct Internet access -- such as your Internet Firewall bastion system itself -- and point your Win-Mosaic clients at this. The disadvantage of this is that you have to run another, large piece of software (the httpd) on your bastion; I was not happy to do this, or
2. You may build a SOCKS-compliant version of this proxy httpd, which can then run on an _internal_ host, and can still access Internet resources on behalf of its Win-Mosaic clients, thus:

           Win Mosaic -> SOCKSified httpd -> sockd -> Internet
                                          or
                                          -> direct -> local 
   

   The advantage of this to SOCKS users is that Internet access remains governed by the configuration of the sockd on your Firewall bastion.

   (Note that this is a scheme already pioneered by Dick St Peters for use with Mac-Mosaic, using an earlier version of WWW redirection mechanism. However, the new WWW Library mechanism makes implementation considerably simpler.)

The Socksized Httpd

The distribution of the CERN httpd (2.17beta) has all the required changes made to it for SOCKS. After unpacking the distribution:

1. cd ./WWW
2. Edit the file `BUILD', to set values for the two variables at the top:

           SOCKSLIB        set this to point to the location of
                           your ready-built SOCKS library; this
                           must be Version 4.2 (or later) built
                           with the -DSHORTENED_RBIND option.
   
           SOCKS_FLAGS     set this to "-DSOCKS" to enable the
                           SOCKS code
   

3. Type `./BUILD'
4. Everything should now build for you. To use your SOCKSized httpd you also need a configuration file, typically /etc/httpd.conf. A simple yet adequate version of this file is this:

           pass http:*
           pass ftp:*
           pass wais:*
           pass gopher:*
           fail news:*
           fail *
   

   (An aside to explain this file, if you care:

   The `pass' lines allow access to remote resources of each specified type. The `fail' line at the end blocks access to any local resources (ie, on the system where the httpd is running).

   For more details on the syntax available in httpd configuration files, including the the very useful use of CACHES, and for how to control which local client systems nay use your proxy, see the URL:

               http://www.w3.org/hypertext/WWW/Daemon/User/Guide.html
   

5. You can now start your proxy server. To run it, listenin on port 80, and logging to a logfile, as root use a command like:

           httpd -p 80 -l logfile
   

   There's also a -v command for verbose output of what its doing, if you hit problems and want to try to work out why.
6. Next you must configure your SOCKS server sockd to allow connections outwards from the httpd daemon. By default, the daemon will change uid to `nobody' and gid to `nogroup' when retrieving a request (though you can change the values using the configuration options `UserId' and `GroupId' in your /etc/httpd.conf file). Thus, this is the `user' who the SOCKS request will appear to have come from. Make sure that your sockd allows it.
7. Now you must point your Win-Mosaic clients at this proxy. Remember that you MUST have Win-Mosaic 2.0alpha2. To define your proxy server, edit lines of this form in your MOSAIC.INI file:

         [proxy information]
         http_proxy=http://proxyhost.your.dom:80/
         ftp_proxy=http://proxyhost.your.dom:80/
         wais_proxy=http://proxyhost.your.dom:80/
         gopher_proxy=http://proxyhost.your.dom:80/