3Com Router 3031, Command Reference Manual

Page: 465 / 838

NAT Configuration Commands 465
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global-addr: An IP address provided for the outside to access (a legal IP
address).
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global-port: A service port number provided for the outside to access. If
ignored, its value shall be the same with the host-port’s value.
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host-addr: IP address of the server in internal LAN.
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host-port: Service port number provided for a server in the range of 0 to
65535, and the common used port numbers are replaced by key words. For
example, www service port number is 80, which can also be represented by
www. ftp service port number is 21, and ftp can also stands for it. If the
inside-port is 0, it indicates that all the types of services can be provided and
the key word any can be used to stand for it in this situation. If the parameter is
not configured, it is considered as the case of any, which is the same as that
there is a static connection between global-addr and host-addr. When the
host-port is configured as any, the global-port also should be any, otherwise
the configuration is illegal.
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global-port1, global-port2: Specifies a port range through two port numbers,
forming a corresponding relation with the internal host address range.
global-port2 must be larger than global-port1.
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host-addr1, host-addr2: Defines a group of consecutive address ranges, which
respectively one-to-one matches the port ranges defined above. host-addr2
must be bigger than host-addr1. The number of the address ranges should be
the same as the number of ports defined by global-port1 and global-port2.
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pro-type: The protocol type carried by IP, possibly being a protocol ID, or a key
word as a substitution. For example: icmp (its protocol ID is 1), tcp (its protocol
ID is 6), udp (its protocol ID is 7).
Description
Using the nat server command, you can define the mapping table of an internal
server. Users can access the internal server with the address and port as host-addr
and host-port respectively through the address port defined by global-addr and
global-port. Using the undo nat server command, you can remove the mapping
table.
Through this command, you can configure some internal network servers for
outside use. The internal server can locate in the ordinary private network or in
MPLS VPN. For example, www, ftp, telnet, kpop3, dns and so on.
Up to 256 internal server conversion commands can be configured on one
interface and at most 4096 internal servers can be configured on one interface.
Up to 1024 internal server conversion commands can be configured in one
system. If the nat servers are configured in the form of port range (i.e., specify a
port range through configuring global-port1 and global-port2, forming a
corresponding relation with the address range of the internal hosts), then the
number of internal servers will be the same as that of the ports configured, and
the max number of them are also 4096.
The interface on which this command is configured is interconnected with ISP and
serves as the gateway of the internal network.
Example
Specify the IP address of the interior www server of the LAN as 10.110.10.10, the
IP address of the interior ftp server as 10.110.10.11. It is expected that the outside