The remote host is missing an update to proftpd announced via advisory DSA 032-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20032-1

The following problems have been reported for the version of proftpd in Debian 2.2 (potato): 1. There is a configuration error in the postinst script, when the user enters 'yes', when asked if anonymous access should be enabled. The postinst script wrongly leaves the 'run as uid/gid root' configuration option in /etc/proftpd.conf, and adds a 'run as uid/gid nobody' option that has no effect. 2. There is a bug that comes up when /var is a symlink, and proftpd is restarted. When stopping proftpd, the /var symlink is removed when it's started again a file named /var is created. The above problems have been corrected in proftpd-1.2.0pre10-2.0potato1. We recommend you upgrade your proftpd package immediately.