Nortel BCM 3.7, Manual

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Programming Operations Guide
Chapter 37
Configuring NAT (Network Address Translation)
Business Communications Manager provides security and firewall features to protect your private
data resources from outsiders.
This section includes information about the different types of NAT, as well as:
• “Enabling and disabling NAT” on page 738
• “Configuring an Interface with NAT” on page 739
The Network Address Translation feature is a network security feature. NAT translates the IP
addresses used within your private network to different IP addresses known to Internet users
outside your private network. NAT helps ensure network security because each outgoing or
incoming request must go through a translation process that also provides the opportunity to
qualify or authenticate the request or match it to a previous request. NAT also translates port
numbers.
NAT is defined by creating a set of rules and then defining the order in which these rules are
evaluated.
Business Communications Manager supports both static and dynamic NAT for a number of packet
types and protocols:
Static NAT
Static NAT is the one-to-one mapping of an IP address on your private network to an IP address
from outside your network. Inbound rules must have external IP addresses mapped to specific
internal IP addresses.
Dynamic NAT
Dynamic NAT is the mapping between a private network and the outside network, of one address
to a pool of addresses, a pool of addresses to one address or a pool of addresses to another. The
mappings are made in a translation table and remain there until the table is cleared or until an entry
times out.
NAT Support for: Type
Packets (static and
dynamic) TCP, UDP, IP
Protocols H.323, FTP, HTTP, POP3, Telnet, SMTP, DNS, TFTP, GOPHER, FINGER, NNTP, RPC,
SUNNFS and SNMP
Note: When using an inbound translation, be sure that all private addresses belong to the
existing systems.