NAT-Traversal (NAT-T) capable IPSec endpoints detect the presence of an intermediate NAT device during IKE phase 1 and switch to UDP port 4500 for all subsequent IKE and ESP traffic (encapsulating ESP in UDP). Without NAT-T support on the peer IPSec endpoints, IPSec protected ESP traffic is transmitted without any UDP encapsulation.

ike 1:YARD_0:965: send IPsec SA delete, spi 95d5b0d1 About NAT Traversal: The Network Address Translation (NAT) is a way to convert private IP addresses to publicly routable internet addresses and vise versa. When an IP packet passes through a NAT device, the source or destination address in the IP header is modified. L2TP over IPSec and NAT -- NAT Traversal L2TP over IPSec and NAT -- NAT Traversal. One of the issues with IPSec and hence VPNs using L2TP over IPSec is the inability to use them in natted environments. In a typical scenario, a VPN tunnel IPsec | pfSense Documentation IKE¶ IKE stands for Internet Key Exchange, and comes in two different varieties: IKEv1 and IKEv2. …

May 03, 2017

Testing a config with an ER-X on the inside of an ER-L, creating an IPsec VPN to another (remote) ER-L. If I try to set this up using Port Forwarding (with auto firewall) I get only TCP and UDP options in the 1.8.5 GUI and no luck in the CLI either:[edit port-forward] admin@gateway# set rule 3 Setting Up IPsec To Use NAT Traversal on Both Sides of the WAN Overview: Setting up IPsec to use NAT traversal on both sides of the WAN. When you are using IPsec to secure WAN traffic, you can set up an IPsec tunnel with NAT traversal (NAT-T) to get around a firewall or other NAT device. This implementation describes how to set up the IPsec tunnel when you have a NAT device on both sides of the tunnel. IPSec VPN Connectivity between Cisco IOS Router GNS3 and

Multiple L2TP/IPsec VPN clients behind a NAT device

What is NAT-Traversal (Network Address Translation