1. Introduction

The repeater application that comes with D-RATS is poorly named and is the source of constant confusion for users.  Some call it the repeater, some call it the ratflector, and others call it the network proxy.  Regardless of what you call it, this document is aimed at explaining what it does, what you can do with it, and how to do some of those things.

2. What it Does

The repeater application works like an ethernet switch, for those that understand that analogy.  If not, imagine it like a Y-adapter or a USB hub.  It allows multiple connections to talk to each other.  Sort of a concentrator of D-RATS traffic that can bridge multiple modes.  If you hook to radios to it, it will behave somewhat like a repeater: any data traffic that comes in on one radio will go out on the other radio.  This could be useful for a cross-band digital data repeater.

If you enable network access, then a user from a networked computer could connect to the repeater and see the RF traffic, as well as communicate with other RF users.  This means you can locate your main D-RATS PC away from the radio (connected by a LAN) or allow multiple stations to share a single radio.  It also allows you to let people come in from across the globe to communicate with RF stations in your area.

If you establish a link between your repeater and another repeater over a network or the internet, then you can bridge your local RF users to remote RF users.

3. Topology

The repeater behaves somewhat like an ethernet switch.  If a packet comes in via one path and has an explicit destination, the repeater will do one of two things:

• If the destination station is known to exist on one of the other attached paths, it will send the packet directly there and anyone else will not see it
• If the destination station is not known (or was last heard more than ten minutes ago) then it will broadcast the packet to all connected paths

Any packet addressed to CQCQCQ (such as a chat packet or a broadcast ping) will always be sent to every port.  The repeater determines which station(s) it has heard on a given path by noting that the station has sent a packet from that path.  This means that if you simply connect to a path of the repeater, the repeater doesn't know where you are until you send something to it (such as a chat message, a ping to another station, etc.

3.1. Scenario 1: An internet reflector

Simply add the single serial port that corresponds to your attached radio and the appropriate baud rate to the list.  Then make sure that "Allow incoming network connections" is still checked and hit the "On" button.  Your proxy screen should look something like this:

In order for you to see the local traffic, you will want to run D-RATS on the repeater machine itself.  To do this, start D-RATS and go to Preferences -> Radio.  Disable the previous serial port path, if one exists and create a new Network path.  The hostname should be localhost and the port will be 9000 if you haven't changed it on the repeater.  Your D-RATS preferences screen should look something like this:

Users can connect to this proxy by connecting to your system via an IP address or DNS name.  If you're behind a firewall, you'll need to forward ports (9000 in this case) through to your internal machine so people from the outside can connect.

NOTE: Please take into consideration the RF network you're providing access to.  If you're linked to a repeater, make sure the owner approves of the additional data load.  If that repeater is linked to a reflector, it's probably not appropriate to provide access to external users that don't realize this unless the reflector owner has made specific provisions for data use.  If you abuse the ability to link network users to RF you will inevitably find data operation banned on the various network nodes.

To do this, you will need two radios, a UHF and a VHF unit.  You cannot use something like an IC-2820 for this because the 2820 does not have two DV chips.  Assume for the sake of this example that the two radios are connected to COM1 and COM2.  First, start the repeater application and add a path each for COM1 and COM2, selecting the proper baud rate.  Your screen should look something like this:

When you have it set, click the "On" button.  Now, anything received on one radio will be sent via the other radio and vice versa, and network users can communicate with RF users.

A recent feature in D-RATS allows the connection a KISS TNC. D-RATS does not currently support the AX.25 protocol and therefore can not be used to run a “Packet Station”. The KISS TNC simply works as a “radio modem”. This lets stations without D-STAR radios use packet radios as an RF connection between D-RATS users. In the scenario above, one radio could be a D-STAR radio and the other a KISS TNC/packet radio combination. This bridges the gap between the two groups.

3.2. Scenario 3: Bridging local RF users to the public ratflector

This scenario is almost exactly the same as most of the ones presented above, except that you need an additional path back to the ratflector.  To do that, add a port of type Network and use ref.d-rats.com for the hostname.  The port should be 9000 or 9001, depending on which ratflector you want to link to.

Once you've done that, you can click On to establish a link to the ratflector, accept incoming connections, and begin repeating out to RF.

4. Authentication

If you decide that you need a minimal level of security in the form of rejecting casual users, you can enable authentication on the proxy.  This will require people to configure D-RATS with a password in order to connect.  To do this, create a text file in the working directory of the repeater called users.txt and place lines such as the following inside:

KK7DS foobar

K7TAY girlie

The format of the file is one record per line, each line is the callsign followed by a space, followed by the password that user must supply.  On Windows this file should go in C:\Program Files\D-RATS\users.txt unless you installed D-RATS to an alternate location.  On Linux or MacOS it will go in the directory from which you spawn the repeater.