All of a sudden our ASA 5520 stops responding to IPSEC clients trying to connect (both tcp/10000 and udp/4500). We don't even get any attempts in our logs. It works one day and stops working another. All other communication inbound/outbound works fine. WebVPN works fine for example.
The problem could be because of DPD's. Try to turn off the DPDs on the problematic client and also on the ASA. Go into the pcf on the problematic computer and set this equal to 1 and then on the ASA under the tunnel-group disable the isakmp keepalive (isakmp keepalive disable).
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...