<blockquote>In computing, the Preboot eXecution Environment (PXE, sometimes pronounced as pixie[1]) specification describes a standardized client-server environment that boots a software assembly, retrieved from a network, on PXE-enabled clients. On the client side it requires only a PXE-capable network interface controller (NIC), and uses a small set of industry-standard network protocols such as DHCP and TFTP..<cite>Wikipedia</cite></blockquote>

== Firmware of the modems ==
The firmware of the modem contain the DHCP responsive of the IP attribution, DNS server. But this DHCP server can define a image PXE. Combining with a TFTP server, the modem can boot an Operating System or a software (**include malware**).

== OLT ==
The OLTs are control and central point to do far communication like GPON used into fiber to home (FTTH). This OLT can download the firmware, edit it and re-upload the edited firmware to do the previously mentioned.

== Tips ==
  * **Disable PXE boot**
  * For the critical zone
    * Take care of your ISP
    * Disable DHCP and enable static IP