ETIC IPL-3G, User Manual

Page: 58 / 100

SET UP
Page 58
User guide ref 9019409-01 UMTS GPRS EDGE router ref. IPL-3G
14.2 Advanced network address and port translation
14.2.1 Principle
This function is available in IPL-3G-1400B, IPL-3G-1201B, IPL-3G-1220B, IPL-3G-1230B routers
only.
That function consists in replacing the source port and IP address or the destination port and IP
address of particular frames received by the router on its interfaces according to configured rules.
It applies to all the frames received by the router on any of its two interfaces except to the IP packets
contained in a remote user PPTP or TLS connection.
It applies as well to frames the destination address of which is the IPL-3G router itself or to frames
the destination IP address is a device belonging to the LAN subnet, or to the WAN subnet or to
another network.
One brings out
the DNAT function which consists in replacing the destination port and IP address.
the SNAT function which consists in replacing the source IP address.
Because the DNAT and SNAT functions modify the IP addresses of the IP packets processed by the
IPL-3G router, and because the firewall filters that frames, it is very important to understand in which
order that different functions are carried out.
Direction
WAN to LAN
LAN to WAN
DNAT FIREWALL SNAT
WAN LAN
Router
LAN
SNAT
DNAT WAN
FIREWALL
Router