If you are manually tweaking the configuration or want to know how much memory to have available in your firewall system, it would be useful to know how much memory each connection takes. The memory requirements for various types of connections are outlined in Table E.1.
Assuming the worst-case scenario (NAT), you would need to allocate at least 57.7MB to handle 100,000 connections.
Simple (e.g., accept, no NAT)
NAT (e.g., a standard connection with NAT)
Resources (authentication, content security, and so on)
General overhead (not per-connection)