I have been working with IPTables for some time when I am working with Linux servers. I have been trying to ease into using FreeBSD servers and have done some reading on the OpenBSD Packet Filter firewall. IPTables have the -m --state options in order to check for connections that are invalid, already established and those that are related to an existing one, etc. I want to know if PF has a stateful checking feature like that. How do I make it check for connections with characteristics similar to what IPTables checks for. The conditions of the connection are "ESTABLISHED", "RELATED", "INVALID", "NEW".