PAC file example

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This example PAC file is used as proxy selector. It can bypass based several factors, or forward to different proxies servers.

function FindProxyForURL(url, host) {
	var privateIP = /^(0|10|127|192\.168|172\.1[6789]|172\.2[0-9]|172\.3[01]|169\.254|192\.88\.99)\.[0-9.]+$/;
	var resolved_ip = dnsResolve(host);
	var myIp = myIpAddress();

	/* Don't send non-FQDN or private IP auths to us */
	// note this will defeat host file entries for external systems
	if (isPlainHostName(host) || privateIP.test(host)) {
		return "DIRECT";
	}

	if (dnsDomainIs(host, "www.acme.com") ||
		dnsDomainIs(host, "webmail.acme.com"))
		return "PROXY proxy.acme.com:3128; DIRECT";

	/*If the host is an internal IP range (RFC1918), send direct */
	if (isInNet(resolved_ip, "10.0.0.0", "255.0.0.0") ||
		isInNet(resolved_ip, "172.16.0.0", "255.240.0.0") ||
		isInNet(resolved_ip, "192.168.0.0", "255.255.0.0") ||
		isInNet(resolved_ip, "127.0.0.0", "255.255.255.0"))
		return "DIRECT";
		
	/* FTP goes directly */
	if (url.substring(0,4) == "ftp:") {
		return "DIRECT";
	}

	// Domains to bypass
	if ((host == "webmail.acme.com") ||
		(host == "www.acme.com") ||
		(dnsDomainIs(host, "sso.acme.com")))
		return "DIRECT";

	if (shExpMatch(host, "*.microsoft.com") ||
		shExpMatch(host, "*windowsupdate*"))
		return "PROXY proxy.acme.com:3128; DIRECT";

	// Balancing based on source
	if (isInNet(myIp, "10.1.0.0", 255.255.255.0") ||
            isInNet(myIp, "10.2.0.0", 255.255.255.0"))
    	    return "PROXY proxy2:8080; PROXY proxy1:8080; DIRECT";


	// Load balancing
	var ipBits = myIp.split(".");
	var mySeg = parseInt(ipBits[3]);

	// Modulus % 2
	if((mySeg % 2) == 0) // Even
		return "PROXY proxy1:8080; PROXY proxy2:8080;";
	else
		return "PROXY proxy2:8080; PROXY proxy1:8080;";

	
	/* Default Traffic Forwarding  */
	return "PROXY proxy1.acme.com:8080; PROXY proxy2.acme.com:8080; DIRECT";
}