You may receive a 550 Access is denied message to a MLSD command when accessing a FTP server published by Forefront TMG 2010
“A FileZilla FTP server was published with Forefront TMG 2010 with a non-web server publishing rule.
The FTP server was accessible with IE9 as FTP client but not with the Filezilla FTP client, which received a 550 Access is denied message; the logs on TMG do not show anything specific.
Below you can see the log from the Filezilla FTP client…”
For more information, check out:
DEBRA LITTLEJOHN SHINDER
MVP (Enterprise Security)