Accton Technology RG211-2.3G, User Manual

Page: 47 / 84

C
HAPTER
7
| NAT Settings
Virtual Server
– 47 –
is widely deployed by service providers to support both voice and video
services over IP networks.
◆
PPTP ALG — Point-to-Point Tunneling Protocol is a method for
implementing virtual private networks.
◆
IPSec ALG — Internet Protocol Security is a protocol suite for securing
Internet Protocol (IP) communications by authenticating and
encrypting each IP packet of a data stream.
V
IRTUAL
S
ERVER
If you configure the CPE as a virtual server, remote users accessing
services such as web sites or FTP servers on your local network through
public IP addresses can be automatically redirected to local servers
configured with private IP addresses. In other words, depending on the
requested service (designated by the TCP/UDP port number), the CPE
redirects the external service request to the appropriate server (located at
an internal IP address). This secures your network from direct attack by
hackers, and provides more flexible management by allowing you to
change internal IP addresses without affecting outside access to local
network services.
For example, if you set Type/Public Port to TCP/80 (HTTP or web) and the
Private IP/Port to 192.168.2.2/80, then all HTTP requests from outside
users will be transferred to 192.168.2.2 on port 80. Therefore, by just
entering the IP address provided by the ISP, Internet users can access the
service they need at the local address to which you redirect them.
The more common TCP service port numbers include: HTTP: 80, FTP: 21,
Telnet: 23, and POP3: 110.
Figure 24: Virtual Server