Symptoms

When attempting to download the remote agent JAR using a web browser (on the same machine as the server) from http://my-server/admin/agent/addRemoteAgent.action the download hangs at 99% done and never completes.

When using wget to download from an Ubuntu machine the download hangs at the same point, then a couple of seconds later reports "Connection closed at byte 97052164. Retrying."

1. When trying to download the file using the server's public hostname (going over a public-facing router), the download hangs.
2. When trying to download using the server's internal IP, the download works.

Cause/Resolution

All the symptoms are indicators that something is blocking the file downloads. Check if there is any URL redirection, any firewall or antivirus rule that might block the download.

For example, the problem can be an ESET AntiVirus's HTTP Scanner feature causing large downloads (100MB or greater) to hang randomly. Disabling the HTTP Scanner feature fixes the problem.