Multitech PROXYSERVER MTPSR1-120, User Manual

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40 MTPSR1-120
Dual Ethernet ProxyServer User Guide
Adding Virtual Servers
The virtual server feature of the ProxyServer enables you to have multiple servers on your local area
network (LAN) with one static IP address (from your ISP or Multi-Tech’s Global Dynamic WAN
Addressing) assigned to the WAN port (if used). A normal Internet connection requires a static IP
address for each server on your LAN. A dual-LAN setup with its Internet connection through a router
with its IP address assigned by an ISP is shown in the following illustration.
Firewall
IP Address
192.168.0.101
Internet
LAN 1
Private
LAN 2
Public
HUB
Router
IP address
204.26.12.10
Internet LAN
IP Address
204.26.12.9
Mail Server
IP Address
192.168.0.40
POP-3 (110)
SMTP (25)
Web Server
IP Address
192.168.0.20
WWW (80)
FTP Server
IP Address
192.168.0.30
FTP (20,21)
HUB
Connecting through a router to the Internet, you ordinarily need a static IP address for each function
(server) you want to perform on the Internet. For example, to browse the Internet with a Web server,
you need an IP address so the router knows where the traffic is coming from and where to send the
reply. In our Internet connection (shown above) we have assigned an IP address of 192.168.0.20 to
the Web server, address 192.168.0.30 to the FTP server, address 192.168.0.40 to the Mail (or E-
Mail) server, and address 192.168.0.101 to the Firewall.
To reduce the number of static IP addresses, a virtual server feature in the Firewall enables you to
map multiple local servers to a single static IP address or to a Global Dynamic WAN port address.
The virtual server feature enables the Firewall to take requests from different servers (functions) and
interact with the Internet based on the functionality of the request. In the normal Internet connection,
this was a physical linkage to a specific IP address. However, the virtual server feature is a functional
connection. Functionality is defined by how an individual server is used; i.e., the Web server uses a
www-http protocol, the FTP server obviously uses FTP, and the Mail server uses the POP3 and
SMTP protocols. Therefore, multiple requests can be sent to the Internet over a single physical
connection and the Firewall will interpret which server is requesting service and forward all packets to
the correct destination.