Nat - Siemens SIMATIC NET SCALANCE SC-600 Configuration Manual

Service
IPsec VPN
SSH
DHCP
Ping
System time
VRRP
3.8.4

NAT

NAT (Network Address Translation) is a method of translating IP addresses in data
packets. With this, two different networks (internal and external) can be connected
together.
A distinction is made between source NAT in which the source IP address is translated
and destination NAT in which the destination IP address is translated.
You will find information on NAT scenarios that are implemented with the device at the
following address: (https://support.industry.siemens.com/cs/en/view/109744660)
IP masquerading
IP masquerading is a simplified source NAT. With each outgoing data packet sent via
this interface, the source IP address is replaced by the IP address of the interface. The
adapted data packet is sent to the destination IP address. For the destination host it
appears as if the queries always came from the same sender. The internal nodes cannot
be reached directly from the external network. By using NAPT, the services of the
internal nodes can be made reachable via the external IP address of the device.
IP masquerading can be used if the internal IP addresses cannot or should not be
forwarded externally, for example because the internal network structure should remain
hidden.
You configure masquerading in "Layer 3" > "NAT" > "IP Masquerading (Page 264)".
NAPT
NAPT (Network Address and Port Translation) is a form of destination NAT and is often
called port forwarding. This allows the services of the internal nodes to be reached from
external that are hidden by IP masquerading or source NAT.
Incoming data packets are translated that come from the external network and are
intended for an external IP address of the device (destination IP address). The
destination IP address is replaced by the IP address of the internal node. In addition to
address translation, port translation is also possible.
SCALANCE SC-600 Web Based Management (WBM)
Configuration Manual, 10/2021, C79000-G8976-C475-03
Access
No
yes
yes
yes
yes
No
Technical basics
3.8 Security functions
yes
No
yes (for the DHCP client
function)
No
No
No
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