Download the latest OpenSSL DLLs:
You need the latest OpenSSL dlls if
you use Windows XP or older, or want to connect to an FTP
server which uses SSL session re-use. This used to work
fine, but Microsoft broke the used function (sChannel)
with a recent security update. After the update, affected
servers will return the following error when connecting:
Download links: 32-bit | 64-bit
The page indy.fulgan.com, from which these DLLs come, is current not available.
Important note for users of Microsoft IIS FTPS server:
There is a bug in IIS with the TLS 1.2 protocol. If you cannot upload files, you either need to install this Microsoft hofix KB2888853 on the server, or use openssl 1.0.0t or older (limiting the connections to TLS 1.0).