Since February, 1994, firewalls have been "safely permeable" for World Wide
Web (WWW) clients via an application level proxy. Proxy support is built
into popular Web clients such as Lynx and Mosaic and works across all
operating systems, not just Unix. The hypertext server developed at CERN,
cern_httpd, provides seamless external access to HTTP, Gopher, WAIS, and
FTP. Thanks to standard proxy support in the clients, and the wide
availability of the cern_httpd proxy server, anyone behind a firewall can
now have full Web access through the firewall host with minimum effort and
without compromising security. The cern_httpd also supports caching so it
is of interest to users that aren't behind firewalls as well. A paper on
WWW Proxies will be presented at the first WWW conference in Geneva at the
end of May. An electronic version is available at
This is an open standard and as such we hope to publish an RFC and
standardize a proxy port number through the Internet authority.
Clients supporting the proxy: Lynx, X Mosaic, Win Mosaic, Mac Mosaic
(unreleased), Emacs WWW browser, CERN line mode browser. If you are a
client writer, and your program isn't on this list, but you support the
proxy, please let us know along with a URL to your client documentation.
You can also contact me for information on adding proxy support, it is
really easy. A full list of clients supporting the proxy is on the
Reference page of the Proxy paper.
This message was not intended as an ad, but I am soliciting direct feedback
from you so that I can find out which clients support the proxy which I may
have missed. I also want to find out which vendors are shipping proxies
that are based on the application level proxy mechanism. These may be based
on the cern_httpd, work as Common Gateway Interface (CGI) scripts, or
something else entirely. At one time, I had gotten email from some of the
firewall vendors indicating their support, but I haven't heard from any of
them in a while. Finally, if you or your organization, corporation, etc. is
using the application level proxy I would like to hear from you. Please
email me directly and I'll summarize for the list in a few weeks.
If you have concerns about application level proxies in general or our
solution specifically, then please raise them on this list rather than
emailing me directly so that we can all participate in the discussion.