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Titan – Plugin “No-Nat”
Plugins are small, independent utilities that are included in the Titan routers. If we require a peculiar characteristic that cannot be found in the current characteristics, let us know at firstname.lastname@example.org. Depending on the size of the project, this could be included as a plugin for free.
Given that the plugins are independent utilities, when a copy of the Titan configuration is created, it is not necessary for the plugin section to be replicated.
The “No-Nat” plugin is specifically designed for IP/Serial gateway situations that have NAT problems; for example, if we have a series of MTX-65i + MTX-Tunnel modems to create a GPRS-RS232 transparent gateway but we have NAT problems (for example, our telephone operator provides SIM cards with private, not public IP address), and we have a PC that uses third party software that only allows we to input IP addresses and ports of the remote devices to create the connection.
A typical representation would be as follows:
However, our GSM operator does not allow this as it blocks all incoming connections to modems. What we can do with the Titan router is the following:
In other words, the MTX-Tunnel modems connect in client mode, meaning that they do not affect the NATs nor the majority of Firewalls. The connection is not made directly with with PC, yet using an intermediary, i.e. using the Titan router’s No-NAT plugin.
On the other hand, our control software will also connect to the Titan’s No-NAT plugin, meaning the Titan router will act as an intermediary between the PC and the different modems.
We will illustrate this with an example:
In this case, we must configure the GPRS modems (MTX-Tunnel) to work in client mode (MTX_mode: client) and so that an identificative chain is sent so that the Titan knows which MTX-Tunnel each connection corresponds to. For example, we can make MTX-Tunnel 1 send “A-000001” (MTX_IDClient: A-000001) as the identificative chain and MTX-Tunnel devices 2 and 3 will send “A-000002” and “A-000003” respectively. Each of them must connect to the TCP port 40000 in the Titan router.
On the other hand, the PC must connect to the Titan’s IP address (for example the local Ethernet address 192.168.1.2) when it wishes to connect to the MTX-Tunnel 1 modem, as well as the corresponding TCP port. For example, to connect to the MTX-Tunnel 1 device, the Titan port 30001 will be used.
Once connected to a socket, the data sent by the PC will be received by the Titan an then reset by the corresponding socket to the MTX-Tunnel to which we wish to connect. Once this data reaches the MTXTunnel device, it will be resent by the serial port.