Use IP filtering to control the flow of network traffic. An IP security policy can define filters that deny or allow a packet access to a z/OS® Communications Server system. Enterprise Extender (EE) IP filters use information in the IP and UDP packet headers to either permit or deny traffic coming into the z/OS CS enterprise. You can write an EE filter rule to allow inbound UDP data from a set of IP addresses to use the defined EE ports. You can write a second rule to allow outbound EE data access to a set of predefined IP addresses. You can also set up the policy to deny any traffic that does not match the previous rules. IP filtering rules can be written to log messages if a packet is denied because the packet did not match the rule. See z/OS Communications Server: IP Configuration Guide for more information about IP filtering.