There are several ftp proxy types known. Each type is using a different login procedure and needs different commands to connect to the target ftp server.
In the list of supported ftp proxy types <server>,<user>,<password> are refering to the target ftp server.
The variables <p_user> and <p_passwd> are userid and password of the ftp proxy.
connect; USER <p_user>; PASS <p_passwd>;
SITE <server>; USER <user>; PASS <passwd>
connect; SITE <server>; USER <user>; PASS <passwd>
connect; USER <p_user>; PASS <p_passwd>;
OPEN <server>; USER <user>; PASS <passwd>
connect; OPEN <server>; USER <user>; PASS <passwd>
connect; USER <user>@<server>; PASS <passwd>
connect; USER <p_user>@<server>; PASS <p_passwd>;
USER <user>; PASS <passwd>
connect; USER <user>@<server> <p_user>;PASS
<p_passwd>;
ACCT <passwd>
connect; USER <user>@<server> <p_user>;PASS
<passwd>;
ACCT <p_passwd>
connect; USER <user>@<p_user>@<server>;PASS
<passwd>;
ACCT <p_passwd>
connect; USER <user>@<p_user>@<server>;PASS
<p_passwd>;
ACCT <passwd>
connect; USER <p_user>; PASS <p_passwd>;
USER <user>@<server>; PASS <passwd>
connect; USER <user>@<p_user>@<server>
PASS <passwd>@<p_passwd>
USER, PASS, SITE, and ACCT are commands sent to the ftp proxy.