Local Only Connection

Hi there,

I am new to OpenWRT and seem to be running into some issues with my setup and apologies in advance if this is a generic question. Basically what I want is to have a router with OpenWRT be able to communicate with 2 devices on the LAN but will not have the access to the internet at all. I am basically creating a test environment where one device has DICOM images and the other device is hosting a DICOM storage server application and transfer DICOM data. I am able to ping the 2 devices successfully but unable to send the DICOM data, am I missing something else? It is using the DICOM protocols but I have verified it can work if I plug both devices into one another without the router in the mix so I believe it is a setting I am missing.

If it's only 2 devices, and it works without the router why have the router at all? Am I missing something here?

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Yes the router is there so we can verify different connections types and authentication protocols. Was hoping to get this router configured for multiple network testing and transferring of data

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I'm not familiar with DICOM, but if it's a normal TCP service, you could try running a port scan with something like nmap to see if you can see the server from the other machine. Example would be nmap -p (dicom port) (server IP), you could try this both on the router and client machine.

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If two or more hosts are on the same network, the router itself is not involved in the traffic between them. That is because the router's core features (routing and firewall) operate at L3, which is not involved if there is only a single subnet.

The only thing the router will do in this situation is:

  • provide a DHCP server, if desired
  • perform as a switch (L2) to connect the two (or more) hosts together.

A simple unmanaged switch would have exactly the same behavior as an airgapped router in your scenario, excpet that a switch would not provide the DHCP service (you'd need static IPs for your hosts, or a DHCP server on one of them).

So what would cause it to behave differently? Maybe some IP configuration issue on the two machines?

Possibly... with no specifics, it's hard to say, though.

Have you conneccted the two machines to a standard unmanaged switch (or just simply directly together)? If so, how did you configure the network interfaces? And did things work as expected?

This helped, found out I fat fingered an ip address in the DICOM portion of our application. I feel like an idiot since it was so simple lol thanks for the help

Other user who recommended nmap made me discover I mistyped something in the DICOM section of our application. I am new to openWRT so I wasnt confident I set it up right. Thanks for the help

Glad you got it figured out!

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