Asus SL1200 - Manual (Page 81)

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Chapter 9 - Configuring Firewall/NAT Settings
ASUS SL1200
9.2.4 Reverse Static NAT
Reverse static NAT maps a globally valid IP address to an internal host
address for the inbound traffic. All packets coming to that globally valid IP
address are relayed to the Internal address. This is useful when hosting
services in an internal machine. Figure 9.5 shows that four globally valid IP
addresses are mapped to four hosts on the internal network and each can
be used to host some services for inbound traffic such as an FTP server.
9.2.5 Reverse NAPT / Virtual Server
Reverse NAPT is also called inbound mapping, port mapping, or virtual
server. Any packet coming to the router can be relayed to the internal host
based on the protocol, the port number or the IP address specified in the
ACL rule. This is useful when multiple services are hosted on different
internal machines. Figure 9.6 shows that web server (TCP/80) is hosted on
PC A, telnet server (TCP/23) on PC B, DNS server (UDP/53) on PC C and
FTP server (TCP/21) on PC D. This means that the inbound traffic of these
four services will be directed to respective host hosting these services.
9.3 Configuring Inbound ACL Rules
By creating ACL rules in Inbound ACL configuration page as shown in
Figure 9.7, you can control (allow or deny) incoming access to computers
on your LAN.
Options in this configuration page allow you to:
• Add a rule, and set parameters for it
• Modify an existing rule
• Delete an existing rule
• View configured ACL rules