cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 192.168.0.5
        netmask 255.255.0.0
        network 192.168.0.0
        broadcast 192.168.255.255
        gateway 192.168.0.254
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 192.168.0.254
        dns-search fritz.box

# Schnittstelle prüfen
pre-up ifconfig wlan0 up
pre-up ifconfig wlan0 down

# Mehrfachkonfiguration aktivieren
iface wlan0 inet manual

# Roaming aktivieren
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

iface zeitsofa inet static
        address 192.168.0.6
        netmask 255.255.0.0
        network 192.168.0.0
        broadcast 192.168.255.255
        gateway 192.168.0.254
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 192.168.0.254
        dns-search fritz.box

iface offen inet dhcp

auto wlan0