SharePoint Ports, Proxies and Protocols .... An overview of farm communications

http://blogs.msdn.com/b/uksharepoint/archive/2009/01/05/sharepoint-ports-proxies-and-protocols-an-overview-of-farm-communications.aspx

http://blogs.technet.com/b/wbaer/archive/2011/09/02/sharepoint-2010-and-windows-firewall-with-advanced-security.aspx

http://msmvps.com/blogs/laflour/archive/2009/11/04/sharepoint-2007-farm-ports-configuring-firewall.aspx

http://www.topsharepoint.com/enable-port-access-for-sharepoint-sites