THE INFORMATION IN THIS ARTICLE APPLIES TO:
When connecting to a TLS resumption-enabled server from EFT, it is common that you will encounter an SSL error shortly after attempting to establish the data socket with the remote server. The below error is typically what you’ll see in the logs in the event that the connection fails due to these reasons.
Note: TLS resumption is commonly used by Filezilla Server and is enabled by default.
227 Entering Passive Mode (13,67,183,127,113,82)
COMMAND:> REST 0
350 Rest supported. Restarting at 0
COMMAND:> STOR Log145416.txt.pgp
STATUS:> Host name 188.8.131.52 resolved: ip = 184.108.40.206.
STATUS:> Connecting FTP data socket 220.127.116.11:29010 (ip = 18.104.22.168)...
150 Opening data channel for file upload to server of "/Log145416.txt.pgp"
STATUS:> Connected. Exchanging encryption keys...
ERROR:> SSL: Error in negotiating SSL connection. The server could be rejecting your certificate.
ERROR:> Failed to establish data socket.
After my investigation of potential ways to remediate this behavior, I found that there was a registry key to enable TLS Resumption compatibility called "ReuseSSLData." After stopping the service, enabling this advanced property (registry key), and restarting the service; this should resolve your issue.
Enable Compatibility with TLS Resumption on FZ Server:
Key: HKLM\SOFTWARE\Wow6432Node\Globalscape\TED 6\Settings\SecuritySSL
Set ReuseSSLData value to "1" to enable "TLS resumption"-compatibility mode in EFT (requires service restart).
What is TLS Resumption?