When you define mappings in Surrogate Socket on a Proxy Server with Packet Filtering enabled, you must also define a custom packet filter for the Proxy Server's external IP's in order for Surrogate Socket to accept (for inbound) or establish (for outbound) connections. Below is a list of common protocols and the custom packet filters which must be added:

NOTE: More restrictive custom filters may be used for your mappings to increase security. For example, you could select a specific local proxy server IP address rather than specifying "Default proxy server external IP addresses," or you could select a specific direction rather than both. This document was designed to work with most systems and therefore lists less restrictive custom packet filters which will work with inbound or outbound mappings regardless of the Listen Address.