Cannot connect via SSL to Secure FTP Server using WS_FTP 7.5

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Cannot connect via SSL to Secure FTP Server using WS_FTP 7.5


THE INFORMATION IN THIS ARTICLE APPLIES TO:

  • Secure FTP Server (All Versions)

SYMPTOMS

Unable to connect to Secure FTP Server using WS_FTP 7.5 via explict FTP over SSL (FTPS) in either Passive or Port modes.  I am able to use CuteFTP just fine.

The error received in WS_FTP is: Failed to create secure data socket

CAUSE

Some older versions of WS_FTP (tested with 7.5 & 7.6) do not adhere to the established standards for FTP over SSL connectivity when establishing SSL connections. The program authenticates properly, however it does not apply the correct PBSZ and PROT sequence necessary to protect the data channel.  Subsequently, it breaks the connection when the server replies with a clear-text directory listing.

RFC 2228 states explicitly that the data connection will be in the clear if no PROT argument is provided.

RESOLUTION

Update to WS_FTP 8 or use CuteFTP.

WORKAROUND

You can cause WS_FTP to issue the proper sequence upon connect. In the Site Options for the particular site, go to the Startup tab and enter "PBSZ 0;PROT P" (sans quotes) in the Initialize Command box. You should now be able to connect and establish a secure data channel using WS_FTP 7.x.



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Details
Last Modified:Thursday, April 12, 2012

Last Modified By: GlobalSCAPE 5

Type: PRB

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