This is the after file
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# Loopback interface
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iface lo inet loopback

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# IPv4 network interfaces
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# --- External NIC ---
iface eth0 inet dhcp
        pre-up sysctl -q -e -w  net.ipv6.conf.eth0.disable_ipv6=1

# --- Internal NIC ---
iface eth1 inet static
        address 192.168.80.1
        netmask 255.255.255.0
  pre-up sysctl -q -e -w  net.ipv6.conf.eth1.disable_ipv6=1
        # DNS Settings for Internal Net
        dns-nameservers 192.168.80.1
        dns-search LinuxMCE

# ---   ---
iface  inet static
  address
        netmask
  pre-up sysctl -q -e -w  net.ipv6.conf..disable_ipv6=0
        # DNS Settings for Internal Net
        dns-nameservers
        dns-search LinuxMCE

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# Activating interfaces
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auto eth0 eth1 lo