What is IPsec NAT traversal?

What is IPsec NAT traversal?

NAT-T (NAT traversal or UDP encapsulation) makes sure that IPsec VPN connections stay open when traffic goes through gateways or devices that use NAT. When an IP packet passes through a network address translator device, it is changed in a way that is not compatible with IPsec.

Is IPsec compatible with NAT?

Unfortunately, conventional NAT does not work on IPSec packets because when the packet goes through a NAT device, the source address in the packet changes, thereby invalidating the packet. When this happens, the receiving end of the VPN connection discards the packet and the VPN connection negotiations fail.

How NAT is detected in IPsec?

Devices exchange two NAT-D packets, one with source IP and port, and another with destination IP and port. The receiving device recalculates the hash and compares it with the hash it received; if they don’t match a NAT device exists.

Why do we use NAT traversal?

Nat Traversal, also known as UDP encapsulation, allows traffic to get to the specified destination when a device does not have a public IP address. This is usually the case if your ISP is doing NAT, or the external interface of your firewall is connected to a device that has NAT enabled.

Where is NAT traversal used?

Network Address Translation-Traversal (NAT-T) is a method used for managing IP address translation-related issues encountered when the data protected by IPsec passes through a device configured with NAT for address translation.

Why is IPsec incompatible with NAT?

The nature of IPsec is to detect and prevent the malicious manipulation of packets between a given source and destination. Therein lies the origin of IPsec/NAT incompatibilities—the nature of NAT is to manipulate a packet, while the nature of IPsec is to preserve the packet’s integrity.

Why is NAT Traversal required?

They do not allow packets from outside the network to come inside, without any of the internal systems requesting for the same. But the very idea of IP telephony is to allow anyone from outside to call anyone inside the network. So, in such cases NAT/Firewall traversal is required selectively.

How do I fix NAT Traversal?

If you are stuck with a NAT type D or C and there are no ways around it, one solution that might allow you to bypass the Switch Error Code 2618-0516 (NAT Traversal Process Has Failed) error is to modify the current DNS settings in order to allow P2P games to function without issues.

Is NAT traversal safe?

Microsoft recently revealed that the way IPSec and NAT-T work can cause a security threat wherein IPSec traffic intended for one computer may be routed to the wrong computer, if certain criteria exist.