I see this is an old thread, but I'm having the same problem with the BT Sync Plugin (2.0.124) on FreeNAS (9.3) and wondered if there was any new information. I have several CIFS users accessing the files on the server but not all users have access to all datasets/directories, based on group permissions. If the application is simply working according to a umask set in the plugin jail for the btsync user, can you suggest how I can modify/override that (and the syntax) to 0007 (rwx:rwx:---)? I've tried adding umask="0007" and umask=0007 to /etc/rc.conf without success, but perhaps it should be in /usr/local/etc/rc.d/btsync? ====== additional background details====== On the FreeNAS, I've setup the users, groups, and datasets, including btsync(UID817):btsync(GID817). On the BTSync plugin jail, I also created btsync (UID817):btsync(GID817), as well as all of the groups with access to the datasets using the same GIDs for each one and btsync is a member of each group. In the Jail's /etc/rc.conf, I set btsync_user="btsync" and btsync_group="btsync" . The datasets are shared with the Jail using "Add Storage". As with the OP, everything seems to work, except files added through the BT Sync application are 755 (dirs) or 644 (files) when they would be 770 or 660 if added through the CIFS interface. One thing that does seem to work is that each file and directory has the correct GID (name and numerical ID) I setup for the datasets using find . -type d -exec chmod g+s {} \; from the root of the dataset (also with -type f for files), just not the correct permissions. Thanks.