setfacl permission issue..
 

mkdir -p /opt/level1/level2/level3
useradd -d /opt/level1/level2/level3 file
setfacl -m u:file:rwx /opt/level1/level2/level3

setfacl -m u:file:--- /opt/
setfacl -m u:file:--- /opt/level1/
setfacl -m u:file:--- /opt/level1/level2/
setfacl -m u:file:rwx /opt/level1/level2/level3

chmod -R 777 /opt
chod -R 777 /level1
chmod -R 777 /level2
chmod -R 777 /level3

by filezila when ever user login with username name file can i just want the user to view and access the particular directory but its listing off all directory inside /opt

setfacl -m u:file:rwx /opt/level1/level2/level3
setfacl -m u:file:--x /

BUT It not working can someone help me how can i give permission in such a way the level3 folder must only wanted to be accessed by user file

you can do this with permissions, but the better way is to change the home folder for user to "/opt/level1/level2/level3" and chroot them into it.

I suspect the reason you are having problems with your example above, is because you are chmodding everything 777 which gives everyone access to everything.