BinTec X3200, User Manual

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282 BinTec Communications AG
Security Mechanisms
7
7.2.7 NAT (Network Address Translation)
➤➤
NAT is a simple-to-operate procedure that can be used for three purpos-
es:
■
Hiding the internal host addresses of a LAN by remapping to one or more
external addresses.
■
Controlling external to internal access. In the external direction, the router
forwards all
➤➤
data packets (forward NAT) and connections from exter-
nal callers are only allowed if explicitly enabled.
■
Permanent monitoring of the connections via the router with indication of
the source and destination addresses and
➤➤
ports . See your syslog
messages for this purpose!
The following figure illustrates the function of forward NAT:
Figure 7-2: Forward NAT
NAT always refers to an interface. X3200 ’s LAN side is always referred to as
"internal", the WAN partner as "external".
B
IA
N
C
A /B
R
IC
K
-X
M
ISDN
192.168.1.1
192.168.1.2
192.168.1.3
ISDN IP
16.0.0.30
LAN IP
192.168.1.254
Forward NAT
?
16.0.0.30
Your Local Area Network
Network of your
WAN Partner
internal
external
access only
after explicit
permission
X3200