i've problems connecting to an ftp-server behind a cisco asa firewall using passive mode. ftp works using active and "extended passive" mode, however: when i turn off "extended passive" (epsv in ftp console client app), it does not work anylonger -- all commands result in a timeout. however we need non-"extended passive" mode for some application we use.
UPDATE / SOLUTION
as it turns out, it was not exactly ASA's fault, or was it? i had to turn of masquerading in proftpd configuration. i had the masquerading-address in proftpd-config set to the IP address of the ftp-server domain and that resulted in unexpected things when passing traffic through the asa. now -- without address masquerading -- everything works very well.