On Monday 16th December 2013 we’ll be changing the content of the proxy auto configuration (PAC) script that web browsers and other applications use to automatically configure use of a web proxy.  The web proxies have been unnecessary for web access since the introduction of NAT at our network border and this change will reduce the number of active clients using them.

The current PAC script provides this configuration (simplified for clarity):

function FindProxyForURL(url, host)
{ 
  return "PROXY 128.240.229.4:8080";
}

This configures web clients to proxy their requests through our load-balanced proxy address at 128.240.229.4. The new PAC config will be:

function FindProxyForURL(url, host)
{
  return "DIRECT";
}

This will configure clients to not use a proxy and just fetch content directly.

We’ve scheduled this change purposely to occur during a quiet time on campus to avoid major inconvenience should any problems arise, however internal testing in ISS over the past few months has shown that this change should be transparent to users.

If you’re aware of any applications or systems that currently have manually set proxy addresses (eg, “wwwcache.ncl.ac.uk”) these can now be removed prior to the eventual full retirement of the web proxies late in 2014.