Remote WiFi and GSM Switches

I have had two IT related issues of late.   Both involve devices on the house networks that have ‘locked up’ and needed a hard bounce – a complete mains power down, wait and switch on again. One of these was in our house in France and one at home.   

The one in France was a lock up of the broadband router.   Clearly once this is down all comms stop and we do have various monitoring systems in place that are important.  Searching online came up with a GSM based mains switched outlet.   This simply plugs into the a wall socket and the device to be controlled plugs into it.   You need to fit a PAYG SIM into the device and then you talk to it with your standard mobile using SMS messages from anywhere there is a mobile phone signal.   As the SMS usage will be very low, a GBP10 SIM will last for ages but it is important to remember that if a PAYG SIM is not used for 3 months it automatically gets cancelled.   Fortunately the device does acknowledge back via SMS each command received so it is possible to maintain SIM activity remotely.  The device has a number of facilities such as temperature measurement and activity scheduling.  This has now sorted the French Connection and I can bounce the router anytime it misbehaves.  Here is the Amazon reference.

https://www.amazon.co.uk/gp/product/B00PKGL7YC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

The home issue was on a device on the home wired network which was important to keep running.   Very occasionally and usually at an inconvenient moment it would lock up and the only way to reset it was a hard bounce.   The device is a pain to get at to do this and if we were away from the house even more so.  Fortunately the WiFi router at home is reliable so all I needed was a WiFi equivalent of the GSM device mentioned above to give the offending device a controlled hard bounce.   Amazon offer one such device which was easy to set up and works a treat.  For those interested it accepts speech commands via Alexa etc

https://www.amazon.co.uk/gp/product/B07KXBQKXX/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Hopefully now we will have remote control of these two weak links in our communication backbone.

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The Power of Fing

While struggling to sort out the network folder issue with PathPilot v2 I mentioned that I could ‘see’ the Tormach and ping it.  One of the readers asked how I managed to find the IP address of the Tormach when it was automatically allocated by the server under DHCP ?

OK I am far from Cisco qualified so the next bit is how I see things work.  When a new device is added to the network for the first time you can either allocate a fixed IP address manually or let the server do that for you.  If you are a bit nerdy like me you might prefer to have a nice ordered manual list of all your main devices.   There is a slight danger that with fixed addressing you can drop the ball and allocate the same IP address to two different devices.   This is not good for the network and leads to smoke coming from ears.

DHCP takes the problem away.  Simply plug the new device into the network and it will talk to the server, get a IP address allocated and off you go.

The server keeps a register of which devices are active and generally will leave the IP address it has allocated unchanged between switch on uses.  It is a simple easy way to do things particularly for the non IT user.

To find if a device is live on your network you can send a ping command to the IP address of the device you are looking for.  The device will respond back and you know all is well.

BUT … if the device has been added using DHCP you will have no idea what the precise IP address of the device is.   So how can you ping something that you don’t know ?

There are lots of geeky commands to solve this problem but there is also a wonderful little App call FING.

FING can be loaded on desktops or portable devices.   When you run it up it sniffs the network and gives a listing of all the devices on the network with their associated IP address.   It also lists devices that have been seen on the network but not currently active.  You can tag names to each device and add icons for similar device types. Here is one of its screens

But that is just the start ….. it gives you the MAC address of each device.  MAC address is a unique number embedded in a network device by the manufacturer.   It is in essence a serial number.  The MAC addresses from a manufacturer will be similar looking so you can identify a device source.

On my wifi system I use MAC address filtering as extra security.  When a friend comes round and needs to log onto my network I can immediately see the device trying to get on but being blocked.  I can see the MAC address of his device and add it to my white list.

So back to the story.   I had loaded PathPilot version 2.0.0, enabled DHCP and connected to the network.  Fing immediately saw the Tormach and it was clearly communicating within the network.   This meant the problem was not network related but something in the Tormach not advertising the shared folder properly.

I thought that was going to be a short explanation post and look how long it ended up.   Short story – FING is a great app.

(BTW I have no connection, affilation, financial involvement etc with Fing.  I just like to tell people about what I regard as really useful apps).

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