Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Mon, 4 Jul 2016 17:02:35 +0200

Hi Steve,

A CA client uses ephemeral ports as originating port numbers, correct.

Ephemeral port numbers are indeed random, and cannot be predicted reliably.

However, if your container contains an IOC (CA server), opening ports

5064&5065 (in the default setup) for both TCP and UDP should allow any

client outside the container to connect. (Not much different to a

container with a web service published at port 80.)

The CA client in the container would still use ephemeral port numbers

for outgoing connections - do you need to publish those?

Cheers,
~Ralph

On 04/07/2016 16:43, Stephen Molloy wrote:

I’m trying to build a Docker container for quick set-up and tear-down

of EPICS instances, and I’ve run into a problem. A CA client outside

the container, but on the same host, cannot see any PV’s served from

inside the container.

Looking at the network traffic with Wireshark, I can see that the

server uses ports 5064 & 5065 as expected, but the ports used by the

client seem to be relatively random. If I could predict them, or

(even better) force them to be specific ports, then I could expose

those ports in the Docker container and (hopefully) the client and

server could communicate properly.

Or perhaps this isn’t the problem, and there is some other network

issue getting in my way.

(I’ve successfully run several EPICS installations on this network and

from this computer, so I am confident that this is an issue with the

Docker set-up.)

Hopefully I’m on the right track with my thinking, and hopefully

someone can let me know how to proceed from here?

In case you’re interested, I’m documenting my work on my blog —

http://www.smolloy.com/2016/07/easy-epics-implementation-with-docker/

Thanks (again) for your time,

Steve

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System