ZyXEL 2WG Guía Del Usuario
Chapter 18 Network Address Translation (NAT) Screens
ZyWALL 2WG User’s Guide
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Figure 248 NAT Application With IP Alias
Port Restricted Cone NAT
ZyWALL ZyNOS version 4.00 and later uses port restricted cone NAT. Port restricted cone
NAT maps all outgoing packets from an internal IP address and port to a single IP address and
port on the external network. In the following example, the ZyWALL maps the source address
of all packets sent from internal IP address 1 and port A to IP address 2 and port B on the
external network. A host on the external network (IP address 3 and Port C for example) can
only send packets to the internal host if the internal host has already sent a packet to the
external host’s IP address and port.
A server with IP address 1 and port A sends packets to IP address 3, port C and IP address 4,
port D. The ZyWALL changes the server’s IP address to 2 and port to B.
Since 1, A has already sent packets to 3, C and 4, D, they can send packets back to 2, B and the
ZyWALL will perform NAT on them and send them to the server at IP address 1, port A.
Packets have not been sent from 1, A to 4, E or 5, so they cannot send packets to 1, A.
NAT maps all outgoing packets from an internal IP address and port to a single IP address and
port on the external network. In the following example, the ZyWALL maps the source address
of all packets sent from internal IP address 1 and port A to IP address 2 and port B on the
external network. A host on the external network (IP address 3 and Port C for example) can
only send packets to the internal host if the internal host has already sent a packet to the
external host’s IP address and port.
A server with IP address 1 and port A sends packets to IP address 3, port C and IP address 4,
port D. The ZyWALL changes the server’s IP address to 2 and port to B.
Since 1, A has already sent packets to 3, C and 4, D, they can send packets back to 2, B and the
ZyWALL will perform NAT on them and send them to the server at IP address 1, port A.
Packets have not been sent from 1, A to 4, E or 5, so they cannot send packets to 1, A.