Sure, this is what firewalls are built for primarily. By default, traffic from an interface with a higher security level (inside with 100) is permitted to interface with lower security level (outside with 0). Only return traffic is allowed.
Sorry for my ignorance but I'm trying to understand this :)
Of course, you're right. Still, I'm having trouble returning the traffic.
I'm pinging from a machine behind inside interface (100) to a maching behind outside (0). I'm sniffing the traffic on the outside and I see the ping request being received and the ping reply being sent. Still, the ASA is denying the ping reply to come back:
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...