Avaya 3.7 User Manual

Network Address Translation (NAT) is an Internet standard that allows private (nonroutable) 
networks to connect to public (routable) networks. To connect private networks and public 
networks, address mapping is performed on a security gateway that is located between the 
private network and the public network.

Note:

Beginning with the VPNmanager 3.2 and the VPNos 4.2 releases, the 
VPNremote Client 4.1 is supported behind a NAT device (DSL or Broadband 
Router).

Beginning with VPNos 4.31, you can set the following three types of NAT mapping on the 
security gateway:

●

Static NAT. With Static NAT, addresses from one network are permanently mapped to 
addresses on another network. One private IP address can be translated to one public IP 
address. Static NAT is bidirectional, that is, for outgoing packets, Static NAT translates the 
source IP address of the packets. For incoming packets, Static NAT translates the 
destination address of the packets. You must specify both the original address and the 
translated address to configure Static NAT.

●

Port NAT. With Port NAT, addresses from internal, nonroutable networks are translated to 
one routable address in Port NAT. Port numbers, in the case of TCP/UDP packets and 
sequence numbers and IDs in the case of ICMP packets, are used to create unique 
channels. Port NAT is unidirectional. That is, Port NAT translates only outgoing packets 
and not incoming, but it does translate the replies. On the way out, the source address of 
the packet is translated. For the replies, the destination address is translated back. You 
can choose from predefined network objects or user-defined network objects, or you can 
specify the IP address and the Mask for the original address. You must specify the IP 
address and the port ranges for the translated address. The port ranges must be in a 
range from 5000 to 65535.

Note:

When using Port NAT, the ESP trailer must be configured in the VPN IPSec 
parameters.

●

Port Redirection. With port redirection, addresses from a specific address and a specific 
port are redirected to another address and port. Port redirection translates the destination 
address of an incoming packet and the source address of the reply. You must specify the 
from address, the to address, and the port number.

By default, NAT is enabled, and the Share public address to reach the internet feature is 
selected. NAT affects only clear traffic.