If you often have to block such hosts it might be good to use object groups. Like that you can easy add and remove hosts in the object group instead add and remove them in the access-list. This helps also to keep short your access-list.
Blacklist on outside interface example:
object-group network Blacklist
network-object host x.x.x.2
network-object host b.c.y.x
access-list outside deny ip object-group Blacklist any
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...