I have a question here!!

If I add a site to the sites I host! they should have an FTP account! they have to have a way to upload their files to the web!

but what if I want to give the user the ability to use SSH! this might creat a problem!

my question is the following, how would I disallowed a user of going to a dirctory lower then his /home/sites/www.site.com .
beascuse if he is able to go blow this he can tell how many sites we are hosting on the server and can get to other sites files and upload them or at least view them!!! some of those files like PHP files has on them a password to the database!!

I know that there is a way to limit a person from going below his or her own dirctory!!

anyone can help here