Nat Server - HPE FlexNetwork HSR6800 Configuration Manual

Figure 51 PAT operation
As shown in
public address and translates their port numbers to different port numbers. Upon receiving a
response, PAT translates the destination address and port number of the response, and forwards it
to the target host.
PAT supports the following mappings:
•
Endpoint-Independent Mapping (EIM)—Uses the same IP and port mapping (EIM entry) for
packets from the same source IP and port to any destinations. EIM allows external hosts to
initiate connections to the translated IP addresses and ports of internal hosts. It allows internal
hosts behind different NAT gateways to access each other.
•
Address and Port-Dependent Mapping (ADPM)—Uses different IP and port mappings for
packets from the same source IP and port to different destination IP addresses and ports.
APDM allows an external host to initiate connections to an internal host only under the condition
that the internal host has previously accessed the external host. It is secure, but it does not
allow internal hosts behind different NAT gateways to access each other.

NAT Server

The NAT Server feature maps a public address and port number to the private IP address and port
number of an internal server. This feature allows servers in the private network to provide services
for external users.
Figure 52 NAT Server operation
Server
192.168.1.3
Figure 52 displays how NAT Server works:
Figure 51, PAT translates the source IP addresses of the three packets to the same
Direction Before NAT
Inbound 20.1.1.1:8080
Dst : 192.168.1.3:8080
NAT
192.168.1.1
Intranet
Src : 192.168.1.3:8080
After NAT
192.168.1.3:8080
Dst : 20.1.1.1:8080
20.1.1.1
Internet
Src : 20.1.1.1:8080
114
Host
20.1.1.2