IPs

Technology

Why Can’t I Hold All These Devices?

Ramen Junkie 0Comment

There are 5 people in my household.  At this point, each of these people has at least a laptop and a tablet and the majority of them have a handheld smartphone style device (only one is actually a phone with data).  There are several game consoles and media devices, a couple of additional desktops, some security cameras, my Pi projects, etc etc.  A quick rundown gives me 33 Devices, though there are more that are not frequently active.

At some point, it became necessary for me to take control and actively manage my home network.  I was getting issues with double assigned IPs from DHCP, I have files on shared drives which need to have static IPs, I needed to implement security and filtering on the network for the kids to keep them from doing things they shouldn’t be doing online as well as tracking usage.

It also helps with security because I know what devices are online and if there are “outside” devices on the network.

So, a quick basic rundown of networking.  Every device, from PCs to Xboxes to iPods, get a unique IP address, most commonly on home networks this will be 192.168.1.XXX.  This is ahow data is pushed around, data has a header that says “I need to go to 192.168.1.XXX, where is that?” and routers and switches push this data around appropriately until some device says “Here I am, send it to me”.  This is really really generalized but it’s the basic idea.

These IPs can often be set up to be static (always the same) on the device, it can be assigned randomly from a pool by the Router (DHCP) or it can be assigned to be static by the Router based on the Device MAC Address.

Every device also has a MAC address.  MAC Addresses are unique to the device interface.  Think of it as a fingerprint.  I say “Device Interface” because if a machine has multiple network interfaces, say, WiFi and a Network cable jack, these will have different MAC addresses despite being one device.  In most routers, you can set up a table of MAC Addresses and tell the router “If you see this MAC, assign it the IP X”.

This is really useful for things like Laptops, Phones and Tablets.  For a machine like a desktop PC or a server that never leaves the network, it may be better to assign the IPs on the device, that is, the Device connects and says “i want to be assigned IP YYY”.  If you have a Wireless device assigned with a static IP, it can cause trouble when that device travels out of network, the static IP may not be available at say, your friend’s house or a coffee shop.  The remote location may use a different IP scheme, they may have their Router assigned to a different IP, there may be another device already using that particular IP.

So why assign IPs?

File servers really need static IPs.  If other devices are connecting to another machine to get say, photos, that other machine, the server, needs to always be in the same place.  Imagine how hard it would be to go to your friend’s home if their home was always in a different location and every building looked identical.

This also avoids IP conflicts.  This is less common since the Router is supposed to not double assign IPs but occasionally if a device disconnects and reconnects while another device is reconnecting, the IP may accidentally become double assigned, which means those data packets go nowhere.  This would be like trying to go to your friend’s address but there are two homes with the same address across the street from each other.

Assigned IPs is also great for security.  Limiting the IP range of DHCP, or limiting the number of devices that can connect keeps the network from getting over loaded by random people, though with a WiFi password this wouldn’t happen anyway.  You could also limit the capabilities of IPs connected through DHCP.  With scanning software you can also know at any time what is connected to your network.  It can also help diagnose issues.  If your unable to get your Wii to watch netflix, you can run a scan and if everything shows up but the Wii, you know the issue is probably on the Wii itself.

It’s also been good for my own experience in better learning methods for managing small networks and configuring the router.  I started off with a list of devices in a spread sheet.  I then gathered all the MAC addresses through a combination of scanning the network or checking the device itself.  Most devices will show you the MAC address in the settings somewhere and if all else fails it’s often printed on a sticker on the back side.

i then sorted out blocks of IPs based on device and sorted everything into these blocks.  This helps organize things.  The only thing that changes is the 4th octet of the IP, so everything is 192.168.1.XXX.  From here I use the following schema:

  • 01-09 = System Devices, the Router, the Wifi Access point, my NAS.
  • 10-20 = Game Consoles and media Devices
  • 21-29 = Desktops, of which there are 4.
  • 30-39 = Handheld Devices belonging to the Kids
  • 40-49 = Laptops
  • 50-59 = My Devices
  • 60-69 = Reserved for IP cameras
  • 70-79 = Reserved for Raspberry Pis and other Internet of Things style devices.
  • 100+ is used for DHCP assignments

This can be modified based on personal needs of course.  The idea is essentially that if nothing shows up under the 100+ IP range, I can know at a glance that nothing unknown is attached to the network.