Connection failed

[Chiamaka Okeke]

Hello Everyone,

I am trying to use Globus to transfer data from one endpoint to another, and below are the error messages I got.

The folders were transferred, but upon inspection, I realized that it was empty (the content of the folders was not transferred).

Message: Fatal FTP response

---

Details: 500-Command failed. : callback failed.\r\n500-globus_xio: Unable to connect to 127.0.1.1:50560\r\n500-globus_xio: System error in connect: Connection refused\r\n500-globus_xio: A system call failed: Connection refused\r\n500 End.\r\n

Any advice or feedback would be appreciated!

Best regards

[Stephen Rosen]

Hi Chiamaka,

This message means that one endpoint was not able to connect to the other over the data channel.

Note the use of that port number in the 50000-51000 range, which is the standard range for data channel connections.

Based only on this information, the best guess would be that your firewall is blocking inbound connections to the data channel ports.

You would have to contact your network admins and have them open these ports.

Network and security teams often are surprised by the use of a wide port-range. If this is a problem, please refer them to sup...@globus.org , where we can answer any questions they may have.

As a quick overview, and because today is a Thursday, here's an ASCII-art connection diagram!

                +-----------------------+
                |       Globus          |
                +-----------------------+
                       /       \
    control channel---/         \
    (TCP port 2811)  /           \----control channel
                    /             \   (TCP port 2811)
                   /               \
                  /                 \
                 /                   \
                v                     v
+-----------------+                 +---------------+
| source endpoint |<--------------->| dest endpoint |
|                 |<--------------->|               |
|                 |<--------------->|               |
|                 |<--------------->|               |
|                 |<--------------->|               |
+-----------------+        |        +---------------+
                           |
                 data channel connections
                 (TCP ports 50000-51000)

This is how most data transfers behave. It's important to note that the control channel connections come from Globus to the endpoints, but the endpoint connections are bidirectional.

There are some special cases, (UDP transfers don't use TCP, GCP to GCS connects in one direction), but the above diagram covers basically how a transfer works.

The fact that your transfer started at all means that those control channel connections to both endpoints worked.

And here we get to an interesting detail: directories were created, but never populated with data.

That's because directory creation can be done over the control channel, but the actual data transfer needs to run over the data channel connections.

I hope that puts you on track towards working data transfers. If not, please reach out to us either here or via sup...@globus.org with more details and we can work on better understanding the situation.

Best,

-Stephen

[Stephen Rosen]

One minor follow-up on this:

Our team was chatting about this issue, and we weren't sure if the advertised IP of the endpoint in that error is as-desired.

I had assumed it was, but "127.0.1.1" probably refers to localhost. That may not be -- in fact, now that my attention has been called to it, it probably isn't -- the IP you want to advertise publicly.

Unfortunately, it's a little hard to guess exactly why the IP would be incorrect. There are a bunch of possibilities depending on how it's configured.

I think we'll need to know at least what version of Globus Connect Server you're using.

Digging into such details may be more appropriate for sup...@globus.org , since it may be quite specific to your case.

-Stephen