SkipPort is a position-independent directive that normally appears toward the top of config.txt/ezproxy.cfg.
SkipPort only applies when using EZproxy in proxy by port. SkipPort is used to identify ports on which EZproxy should never attempt to create virtual web servers, such as ports that are used to provide other services on the same server. SkipPort should be followed by a port number that EZproxy should not use. An EZproxy configuration can contain any number of SkipPort directives.
In this example, EZproxy will never assign ports 2300 or 2500 or use by any virtual web servers.