I use samba3.0(red hat 9) to share files with friends.

I set one directory permission is uploadable and readable,
un-deletable.
because the directory is writable,
users can change file permissions in this directory.
after changing the permissions, users can delete the file.
how to set the right files permissions?

and i find using smb://my_ip_address cannot access samba server in
linux(red hat 8 & 9, or fedora)
but using command mount is ok
somebody can tell me the reasons?

thank you advanced.