User's Manual

Reference Manual for the NETGEAR ProSafe VPN Client
9-6 Troubleshooting
202-10015-01
Network Address Translation (NAT)
Network Address Translation (NAT) devices are widely deployed to enable local area networks
(LANs) to use a single set of external IP addresses for an entire network.
Remote users commonly encounter NAT devices in home networks, broadband modems (cable
and DSL), and hotels. Although an IPSec VPN connection can coexist with NAT devices,
IPSec-NAT incompatibilities may occur. To prevent these incompatibilities, the client employs the
latest of the emerging standards for NAT-Traversal (NAT-T).
When connecting to a peer (remote) device that implements the same NAT-T standard (there are
several), the client automatically detects the presence of the NAT device; you don't have to
configure anything. Then, the client and the peer device encapsulate the IPSec packets inside UDP
packets; this allows the VPN connection to traverse the NAT device without requiring any changes
in the NAT device.
When the client connects to a peer device and detects a NAT device, Log Viewer messages
indicate this detection. Here is a sample of these logged messages: