Doing a single change in the patch '700_prefer_tls.diff'
to the effect of re-adding
/* netkit-ftp-0.17/ftp/ftp.c:1675 */
SSL_copy_session_id(ssl_data_con, ssl_con);
will solve the problem completely when building against
libssl1.0-dev, i.e., linking with libss1.0.
However, when building with libssl-dev, i.e., libssl1.1,
the resulting binary is able to execute exactly ONE data
connection with success. The rest are denied as before.
The error message from Proftpd is still 'Not owner.'.
Clearly there is a bug in libss1.1. For the time being
a rebuild against libss1.0-dev, with the above code line
uncommented, is my recommendation in the role as maintainer
for this package.
