Senín ( con n )

Permitir a todos los usuarios montar con cifs

chmod +s /sbin/mount.cifs

Permitir desmontar ( opción user en el /etc/fstab ):

//server/usersharename /mnt/username cifs user 0 0

Más info en :
cifs-linux

Ejemplo de configuración de /etc/networking/interfaces de plesk

auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 55.21.199.252
        netmask 255.255.255.0
        network 55.21.199.0
        broadcast 55.21.199.255
        gateway 55.21.199.1
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 199.202.55.10
        dns-search senin.org

iface eth0:1 inet static
        address 55.21.199.253
        netmask 255.255.255.255
auto eth0:1

iface eth0:2 inet static
        address 55.21.199.254
        netmask 255.255.255.255
auto eth0:2