POP Through HTTP Proxy

You can use openvpn http://www.openvpn.net/. On client side use protocol TCP and proxy. On server side use protocol TCP and port share with apache server not work on Windows.

There are at least two ways of doing this:

1. Proxy auto-configuration URL via DHCP
2. Transparent proxy redirection with iptables

The first option uses WPAD mechanism:

In your DHCP server config, you must include option 252 (e.g. for dhcpd):

option local-proxy-config code 252 = text;
...
subnet 192.168.0.0 netmask 255.255.255.0 {
  range 192.168.0.20 192.168.0.30;
  ...
  option local-proxy-config "http://your_http_server/proxy.pac";
}

Your proxy.pac is just a bit of JS which tells the browser what to proxy (e.g.):

function FindProxyForURL(url, host) {
    var proxy = "PROXY your_proxy_server:3128; DIRECT";
    var direct = "DIRECT";

    // no proxy for local hosts without domain:
    if(isPlainHostName(host)) return direct;

    // proxy everything else:
    return proxy;
}

The second option is to use iptables to redirect http traffic transparently (e.g.):

iptables -t nat -A PREROUTING -i eth0 -s ! your_proxy_server -p tcp --dport 80 -j DNAT --to your_proxy_server:3128
iptables -t nat -A POSTROUTING -o eth0 -s local-network -d your_proxy_server -j SNAT --to iptables-box
iptables -A FORWARD -s local-network -d your_proxy_server -i eth0 -o eth0 -p tcp --dport 3128 -j ACCEPT