The best way to filter traffic over a VPN, in my opinion, is:
1) build the Encryption domain based on subnets for all IP.
2) add entries to the inbound ACL on the outside interface (assuming that's where the VPN terminates) to filter traffic as desired.
3) enter "no sysopt connection permit-ipsec" to force ALL vpn traffic through this ACL.
"sysopt connection permit-ipsec" is enabled by default and "Implicitly permits any packet that comes from an IPSec tunnel, and bypasses the checking of an associated access-list, conduit, or access-group command statement for IPSec connections". Remember that this affects all VPNs so you must have the necessary rules in the ACL beforehand.
It might be a good idea to set up syslog on your firewall so you can capture any messages from the time of it freezing up.
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...