Ari Luotonen, CERN, 1994

Setting Up Clients To Use a Proxy

Clients (currently Mosaic 2.2 and Lynx 2.3, and newer) can be set up to connect to the outside world through proxies by setting the following environment variables:

http_proxy
ftp_proxy
gopher_proxy
wais_proxy

to URLs of a cern_httpd running as a proxy.

Example of a Script Starting Up a Client

    #!/bin/sh
    http_proxy="http://www.cern.ch:911/";   export http_proxy
    ftp_proxy="http://www.cern.ch:911/";    export ftp_proxy
    gopher_proxy="http://www.cern.ch:911/"; export gopher_proxy
    wais_proxy="http://www.cern.ch:911/";   export wais_proxy
    exec Mosaic

These environment variables affect also CERN httpd itself when it's running as a proxy, that is, the proxy will use another proxy to access remote servers instead of connecting to them directly. This is the intended behaviour since there are times when a connection to the outside world has to be made through two proxies. However, it can sometimes be also a source of confusion, if e.g. proxy environment variables are set in one's .cshrc (or such) file, and one then starts proxy by hand.

no_proxy

Some clients support the no_proxy environment variable that specifies a set of domains for which the proxy should not be consulted; the contents is a comma-separated list of domain names, with an optional :port part:

        no_proxy="cern.ch,ncsa.uiuc.edu,some.host:8080"
	export no_proxy

httpd@info.cern.ch