Vanguard 3000 Multicarrier Cellular Data Modem & IP Router PN 134732-VG3000 Rev. D| Page 88
192.168.1.250. The Vanguard then modifies the destination IP address and port number before forwarding the packet
onto the local area network.
Figure 60: Port Forwarding Example
Port forwarding is useful for field applications that use polling that is initiated by a polling master. The port forwarding
function allows the polling master to establish a data connection through the Internet. The incoming polling message is
forwarded by the Vanguard to the appropriate PLC or RTU on the Vanguard’s local area network.
4.5
DMZ
Alternately, DMZ can be enabled on the Vanguard router. When DMZ is enabled, all traffic destined to the Vanguard’s
cellular IP address that is received from the Internet is forwarded to the DMZ host. The IP address of the DMZ host is
specified by the user. Using DMZ can eliminate the need to specify many individual port forwarding rules. However, by
exposing all the ports on the local device, the local device may become more susceptible to attacks.
If specific Port Forwarding rules exist in the IP Mapping Table, they will take precedence over the DMZ host.
4.6
FRIENDLY IP ADDRESS
Friendly IP addresses can be used with either port forwarding or DMZ to provide an additional layer of security. When
Friendly IP addresses are used, the Vanguard will only forward packets to the LAN if the source IP address of the
received packet matches either the specific IP address or range of IP addresses specified in the Friendly IP address field.
This feature can be disabled by entering 0.0.0.0 in the friendly IP address field. In this case, packets from any host on
the Internet can be forwarded to the LAN when either DMZ or Port Forwarding is enabled.
