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drcsim constellation field computer <-> OCU communication

asked 2013-06-04 06:59:07 -0500

Hello, we are trying to communicate between OCU and Field Computer over UDP, but we have a problem with getting it to work. We use IP 11.8.02 for OCU and for FC1, but what port numbers should we use?

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answered 2013-06-04 11:45:00 -0500

gerkey gravatar image

The OpenVPN tunnel on the router ( / will forward all unicast IP traffic, including unicast UDP, on all ports. Are you trying to use multicast or broadcast UDP? That won't work across the OpenVPN tunnel.

Assuming that you're using unicast UDP, it should work on any port. Here's a simple test:

On one side (e.g., on fc1), start a netcat listener:

# Listen on port 1234 for UDP traffic
netcat -u -l 1234

On the other side (e.g., on the OCU), start a netcat talker:

# Send UDP packets to a listener on port 1234
netcat -u 1234

You should then be able to type characters into either console and see them echoed on the other side (after pressing return). If that doesn't work, try TCP, which you would do by removing the -u argument to both commands (TCP is the default).

If that doesn't work, then there's probably something wrong with the routing tables. I would start with the basics:

  • from OCU, ping
  • from OCU, ping
  • from OCU, ping
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Thank you for your help. We are using unicast UDP and finally got this working on 1234 port. Netcat worked just fine.

piotrkaczmarek gravatar imagepiotrkaczmarek ( 2013-06-04 15:16:14 -0500 )edit
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Asked: 2013-06-04 06:59:07 -0500

Seen: 123 times

Last updated: Jun 04 '13