What is the primary function of an ingress filter in a network?

The primary function of an ingress filter in a network is to block undesired traffic from entering a network. Ingress filtering is a security measure applied at the entry point of a network, where it examines incoming packets and determines whether they should be allowed through based on predefined rules. This helps in mitigating threats such as malicious attacks, unauthorized access, and denial-of-service attacks by preventing harmful traffic from affecting the internal network.

By implementing ingress filters, network administrators can ensure that only legitimate and intended traffic reaches the network, enhancing overall security and integrity. This filtering can be based on various criteria such as IP addresses, protocols, or port numbers, thereby providing an essential layer of protection against external threats.