Tag: embedded devices

Falsehoods Smart-Device people believe about Home Networks

A few years ago someone posted a great article about the bad assumptions programmers make about names; here’s a similar list about assumptions about home networks and smart devices.

We all remember the excellent Falsehoods people believe about names don’t we?

Having lived with a few smart devices sharing my network for a while, I thought we need a similar one about smart devices and home networking.

Items marked with a * contributed or inspired by @davidmoss

  • The WiFi is always available
  • The WiFi is continuously connected to the internet
  • The WiFi network isn’t hidden
  • The WiFi network isn’t restricted by MAC address so they can be hidden from the user
  • The WiFi network doesn’t use strong authentication like WPA2
  • The WiFi network definitely doesn’t use authentication mentioning the word ‘Enterprise’
  • The user knows the exact authentication type is use for the WiFi, so no need to auto-detect it*
  • There is only a single WiFi network
  • The name of the WiFi network is ASCII*
  • There is only a single access point for the WiFi network
  • Any device connected to the home-network is trusted to control the smart devices on it
  • Smart devices and their controllers are on the same network
  • Devices on the network can connect directly to each other
  • The network is simple, and doesn’t use other technologies such as powerline1
  • All networks have a PC type device to install/configure/upgrade devices (and that device is running Windows)*
  • There is always a DHCP Server*
  • Devices will always get the same IP address on the internal network from the DHCP server
  • DHCP device names don’t have to be explanatory, because nobody ever sees them
  • Devices can have inbound connections from the internet 2
  • The network is reliable without packet loss
  • The connectivity is sufficient for all devices on the network
  • The performance characteristics of the network is constant and doesn’t change across time
  • The Internet connectivity isn’t metered, and there’s no problem downloading lots of data
  • Encryption of traffic is an overhead that isn’t needed on embedded devices
  • Predictable IDs like Serial-Numbers are good default security tokens
  • Unchangeable IDs like Serial-Numbers are acceptable security tokens
  • The device won’t be used as a platform for attacks, so doesn’t need hardened from threats internal and external to the network. 3
  • Devices can be shipped and abandoned. They won’t be used for years, as so any future software vulnerabilities can be ignored
  • IPv6 is for the future, and doesn’t need to be supported4

What have I missed?

  1. These should be layer 2 transparent, but they can disrupt Multicast which can break bonjour ↩
  2. aside from security implications, ISPs are moving to a carrier-grade NAT to work around IPv4 address exhaustion, so inbound ports may not be possible ↩
  3. many devices have a pretty complete Linux stack, at least complete enough for attackers to use ↩
  4. Chicken and Egg this one ↩