SOLVED: FireFTP / ProFTPd Error ‘Unable to build data connection: Operation not permitted’

Posted on Thursday, September 16 2010 under , ,

After updating ProFTPd on a server running FreeBSD, certain clients (FireFTP specifically) were able to log in, but not transfer files or retrieve a directory listing. The following error was shown to the client user:

425 Unable to build data connection: Operation not permitted

It appears that a recent change in ProFTPd's default TLS handling rules requires SSL sessions to be re-used, which FireFTP does not do. Looking at the TLS log file shows these kinds of errors:

Sep 17 12:31:43 mod_tls/2.4.1[9592]: client did not reuse SSL session, rejecting data connection (see TLSOption NoSessionReuseRequired)

The fix is simple, add the following to proftpd.conf and restart ProFTPd:

TLSOptions NoSessionReuseRequired

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>