Re: TCP connect doesn't establish through IPSEC tunnel
most common reasons is if a router, PIX Firewall, ASA or VPN Concentrator loses dead peer detection (DPD) keepalives on the path.
DPDs are used in order to verify if the remote peer still answers, because it is unsafe to keep a connection active if the remote device is dead. To a device that loses these packets, it means that the peer no longer responds to ACK for DPD, and therefore, is not reachable.
The Internet Key Exchange (IKE) keepalive packets are sent every 10 seconds, by default. Once three packets are missed, an IPsec termination point concludes that it has lost connectivity with its peer.
In order to resolve this issue, issue the crypto isakmp keepalive command on the Router. This allows the gateway to send DPD messages to the peer.
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...