Using Rtd_echo

You can use the rtd_echo utility program to help configure real-time display transmissions on complicated networks. This program reads the RTD socket traffic on a computer and retransmits it to another address. It can change both the destination address and port number.

The configuration is available with command line options. To see the choices, run rtd_echo -?.

Only one program can read from a socket port. If you are running rtd_echo on a machine, then another rtd_echo, or the rtdisp utility cannot read from the same port.

Typical uses for rtd_echo are:

• Transmitting data to a target host which is not directly accessible from the source system (that is no network route, you cannot ping directly).

• Transmitting data through network routers and switches which do not allow broadcast addresses.

• Transmitting data once through a limited bandwidth line, then echoing with a broadcast address, or multiple distinct addresses to lots of machines.

  In this case, if you are echoing to a network address which includes the echoing machine, you must use a different port number. This is to prevent rtd_echo from reading its own output and producing an infinite loop.

  Here is an example of how to configure:

  • Radar machine: 2 outputs in setup/RVP: 127.0.0.1 Port 30730, 192.168.45.1 port 30731.
  • Echo machine (192.168.45.1): Run rtd_echo –a:192.168.45.255 –i:30731

  This gives the following features:

  • All rtdisp programs can be configured the same to read from port 30730.
  • rtdisp works on the radar machine (using the 127.0.0.1 address).
  • rtdisp works on all the 192.168.45 network including the echo machine.

Once you have rtd_echo working fine from a shell command, add it to your /etc/rc.d/rc.local file with a trailing & so it runs every time you boot.