I may not be understanding your question correctly, but if you simply want to disable the firewall on the 1841, it will depend what version of IOS firewall you are using.
For CBAC, you'll have to remove the 'ip inspect name out' command from your interface, and most likely the ACL on that interface as well to allow traffic to flow normally.
For zone-based firewall, you can simply remove the 'zone-member' commands from each of your interfaces. This will leave the rest of your firewall configuration in tact, should you choose to go back and re-add the zone memberships at some point to re-enable the firewall.
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...