Hiya, If you see this error message in /var/log/messages when trying a snapshot & are unable to connect to ftp servers, check your PF config file.
Taking the complete ruleset from the PF FAQ, the rule pass in quick on $int_if inet proto tcp to any port ftp rdr-to 127.0.0.1 port 8021 needs to change to pass in quick on $int_if inet proto tcp to any port ftp divert-to 127.0.0.1 port 8021 See the configuration section of ftp-proxy(8) Sevan / Venture37