Draytek Vigor IPPBX 2820n, User Manual

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VigorIPPBX 2820 Series User’s Guide 227
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Enhance security of the internal network by obscuring the IP address. There are
many attacks aiming victims based on the IP address. Since the attacker cannot be
aware of any private IP addresses, the NAT function can protect the internal network.
On NAT page, you will see the private IP address defined in RFC-1918. Usually we use
the 192.168.1.0/24 subnet for the router. As stated before, the NAT facility can map one
or more IP addresses and/or service ports into different specified services. In other words,
the NAT function can be achieved by using port mapping methods.
Below shows the menu items for NAT.
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Port Redirection is usually set up for server related service inside the local network (LAN),
such as web servers, FTP servers, E-mail servers etc. Most of the case, you need a public IP
address for each server and this public IP address/domain name are recognized by all users.
Since the server is actually located inside the LAN, the network well protected by NAT of
the router, and identified by its private IP address/port, the goal of Port Redirection function
is to forward all access request with public IP address from external users to the mapping
private IP address/port of the server.
The port redirection can only apply to incoming traffic.
To use this function, please go to NAT page and choose Port Redirection web page. The
Port Redirection Table provides 20 port-mapping entries for the internal hosts.