Siemens SE105 - Manual (Page 74)

73
Configuration with Advanced Setup
Gigaset Router / de / A31008-E105-B100-2-19 / configure_router.fm / 05.06.2003
NAT Configuration
Your Gigaset Router comes supplied with the NAT function (Network Address
Translation). The NAT function acts as a firewall against unauthorised access from the
Internet.
◆ All the local IP addresses of the PCs in the local network are mapped to the router's
Public IP address . This means that each PC on the local network communicates with
the Internet via the router's IP address. One advantage of this is that only one
Internet access has to be bought from the Internet Service Provider even if you use
several PCs. A further advantage is that the PCs' local IP addresses remain
anonymous thus preventing any direct external access to the PCs on the local
network. The router knows which PC has launched which Internet application and
ensures that each local user receives the right data.
◆ No data from the Internet is allowed into your local network unless it has been
explicitly requested by one of the PCs on that network.
◆ The router opens only one Port for each Internet application, e. g. for email, FTP or
HTTP.
You can use the router's NAT settings to
◆ configure address mapping.
If you have several public IP addresses, your PCs can use them as well as the router's
IP address to connect to the Internet. This can be done by configuring the address
mapping appropriately (see page 74).
◆ set up the router as a virtual server.
If you want to offer files or Web services that are on a PC in your local network to
other Internet users, you will have set the router up as a virtual server (see page 75).
◆ configure Special Applications
Some applications, such as games, network conferences and voice over Internet,
will not work if Network Address Translation (NAT) has been activated. If you want
to use such applications nevertheless, then you will have to configure them as
"Special Applications" (see page 76).