as an act of digital hygiene, I installed abloprox on a raspi and added this PAC file to save some keystrokes when configuring:
function FindProxyForURL(url, host) {
if (shExpMatch(host,"*.fritz.box")) return "DIRECT";
if (shExpMatch(host,"*.local")) return "DIRECT";
if (shExpMatch(host,"*.akamaistream.net")) return "DIRECT";
if (shExpMatch(host,"*.m945.mwn.de")) return "DIRECT";
// auto config:
// 1. ensure there's a host 'wpad' in the current network, see
// - https://en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol#Context
// - http://fritz.box/net/network_user_devices.lua
// 2. have a http webserver running on that host
// 3. ensure http://wpad/wpad.dat or http://wpad.fritz.box/wpad.dat contains a PAC file like in http://blog.mro.name/2014/06/ad-blocking-proxy-abloprox/
// return "PROXY wpad:3126"; // Default return condition is the proxy on host 'wpad'.
return "PROXY <hostname_of_the_raspi>:3126"; // Default return condition is the proxy.
}
Update: I pushed this one step further recently and use the automatic proxy-configuration itself to filter — see http://purl.mro.name/wpad.
Update: hu – it took Android until version 5.0 (lollipop) to support PAC.