The modem is placed into GRE mode by configuring the first proxy line to use 1723 as
listenport
and
remoteport
and by setting the second and third proxy lines for type 3 and 4
and port 0.
* See the examples below for more information and practical application.
In GRE mode, the proxy first sets up a TCP connection to
remoteaddress
and then lays a
GRE tunnel over the TCP pipe. This type of connection is very useful in that it will allow
all ports to pass through to and from the remote IP as long as the remote system supports
GRE.
The third argument <
count
> is used to tell the modem how many concurrent sessions to
allow for that particular proxy connection.
The fourth argument <
listenport
> is the port on which the modem listens for incoming
connections for all transport methods (TCP/UDP/GRE). This port receives all data before
it is processed by the proxy. Regardless of the direction of the data traffic flow (either
inbound or outbound), the modem always monitors
listenport
for any data to be routed. If
the modem encounters traffic on the specified
listenport
, the proxy is activated and
begins to route the data as specified in the proxy command line.
The fifth argument <
remoteport
> is the forwarding port, that is, after data has been
processed by the proxy, it is routed from
listenport
to
remoteport
. All data intercepted on
listenport
is forwarded out of the modem on
remoteport
. Even if the data is sent out over
the ethernet connection to a local non-routable IP address, it is considered remote because
that IP address is external to the modem. The only IP considered local to the modem is
the IP of the modem’s ethernet jack (Please refer to the AT+LCETHI command).
The last argument <
remoteaddress
> is the remote host to send data to. During an
outbound request where data is sent from the modem to a remote system on the internet,
remoteaddress
is the destination point. Any data entering the modem’s ethernet jack on
listenport
will be forwarded to
remoteaddress
on
remoteport
.
The same is true for incoming data: If traffic is seen inbound from the cellular side on
listenport
, the proxy will route it from the ethernet jack to
remoteaddress
on
remoteport
.
Keep in mind that the IP is remote only as far as the modem is concerned. A private non-
routable IP is still considered remote as long as it is physically outside the modem. It is
for this reason that you can set
remoteport
as a local address such as 192.168.1.35 and the
modem will accept incoming data from the cellular side and forward it through the
ethernet jack to
remoteport
.
Default:
No Saved Proxies
Storage:
N/A
Command Values:
AT+LCPROX=
<parameters listed below>
=<id>,<type>,<count>,<listenport>,<remoteport>,<remoteaddress>
Defines a proxy as per the settings below.
AT+LCPROX?
Queries all currently saved proxies.
Where:
<id>
Number 1-8 (You can define up to 8 proxy configurations).
