Web Client File Upload Fails Outside of Internal Network due to Reverse Proxy

I have an interesting one here....I'm doing some testing with Cerberus 11.3. I have an IIS reverse proxy setup to forward http & https requests to my internal network/servers. I've been using the reverse proxy for several years and works fine. I have it setup to forward https requests for the Cerberus Web Client to the Cerberus FTP server on my internal network. With this setup I can login, navigate the folder structure, download files, and everything seems good except when I try to upload any file approximately larger than 19-20 mb. When I do that I get two error messages. One at the top says "Unable to communicate with the server: Your session may have timed out" and "null Unknown error". If I upload a file smaller than 19-20mb the upload works fine. I've taken screen shots of the error messages below.

I did some testing and uploads larger than 20mb work fine when I access the Cerberus web client from an internal computer. I created an additional HTTPS listener on port 449 and created a firewall port forwarding rule to forward that port directly to the Cerberus server. With this configuration I am able to upload files larger than 20mb without an issue. So this leads me to believe the issue is with the IIS reverse proxy or how I may have it configured.

I've also included snippets from the log file when using the reverse proxy and when I have direct connection on port 449.

Has anyone run across something similar or familiar with reverse proxies to recommend any settings to change?

Thanks in advance for any help/suggestions!
Josh

Log file with reverse proxy (upload not successful)

Log file with direct connection (upload successful)

Dana Anderson

December 17, 2020 14:08

Hi, Josh.

By chance does your reverse proxy have any settings for max file upload?

Ian Butteriss

December 17, 2020 14:13

Hi Josh,

Also, there are cases were buffer size, timeout, temp file write size and client max body size settings needed to be adjusted. A Google search for "upload through reverse proxy failing" revealed several blog posts on the topic.

Josh

December 17, 2020 17:21

Thank you Dana and Ian for the suggestions and direction on where to search.

I found this thread which talks about the max file sizes.

IIS had a default max file size of 240 mb, however I still had issues. I increased the max file size and all is good now. Thank you again!

For reference if anyone is having issues in the future, below are screen captures of where to set the max file size.

Web Client File Upload Fails Outside of Internal Network due to Reverse Proxy

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