Z-Net: Preventative Maintenance Required

[SeattleDavid]

One of the things I discovered the hard way was that Z-Net devices require regular preventative maintenance or else they will catastrophically fail, leaving your system out of service.

SD Cards have a limited life, and this is shorter than you probably think. Our experience is that the SD Card in a Z-Net device will fail in the 3~4 year timeframe. We have six Z-Net devices and two of them failed before we realized it is because of a systemic design failure.

Normally, embedded systems running on a Raspberry Pi need to take steps to minimize unnecessary writing and swapping to the SD card, in order to prevent premature failure. However, it appears that these steps have not been taken in the design of the Z-Net. (Google "raspberry pi minimize writing to sd card to prevent wear" for more information on this.) Consequently, the SD card is constantly being written to and it will wear out. Since the particular brand/model that HomeSeer uses (Transcend Silver) is not an especially robust SD it will fail sooner than if an endurance SD had been used...but those cost about $3 additional.

Make an image of your working SD card before it fails. It will take about an hour to do. (Google "how to make an image of an SD card") Then, keep the image for when the day arrives.

If you are the sort that doesn't want the system to go down at an inconvenient time (such as in a snowstorm when you are on a vacation far away and you need your home to remain heated) you should consider a routine maintenance program. At a suitable interval (I would suggest about 3 years or less) simply replace the SD card.

Whether you wait for the Z-net to actually fail or you are doing a preemptive swap, it is very easy:

1. Using the image you made when the card was still working, copy the image to the new SD card.
2. If your Z-Net is still working, go into HomeSeer and to Device Configuration and for the interface, choose the option to back it up.
3. Power down the Z-Net and open the case. Swap the SD card.
4. Power the Z-Net back up and everything should be working again perfectly. Unless you are using static IP addressing on the Z-Net device itself it will just work. (And, if you are using Static IP addressing, if you make your image after setting the Static IP then it will also be as simple as swapping the SD.
5. It appears that the Z-Wave configuration information is all stored in the Z-Wave daughter-board, which is super convenient. So swapping the SD card just works.

You should also beware that SD cards have a second failure mode that isn't widely discussed. If the SD is powered down while writing then the entire SD can become corrupted. Look inside the Z-Net device and you will see an occasionally blinking green LED. That is the game of Russian Roulette underway. Power the Z-Net down at the wrong instant while the green light is on and it will fail.

Be prepared, plan ahead, image your Z-Net device before you have to buy a new one. (The Z-Net SD image is not available for download, by the way.)

[mterry63]

Good advice, also available in other threads on the board. There are also threads on how to backup the SD card. Because I keep reading it here, I did make a copy today. My Z-Net is about 14 months old. I'd recommend anyone who has a Z-Net track down the login credentials for SSH and test them out. Windows 10 has a built-in ssh client these days from the command prompt. Before maintenance login and execute

sudo halt
or
sudo poweroff (an alias)

for a clean shutdown.

[SeattleDavid]

WTF? There's an SSH back door to the Z-Net???!!!

It would have been kinda nice if they had provided a "Power Down" button on the web UI, but I no longer expect that level of accommodation from the HS UI designers.

I'm also somewhat concerned about installing security patches to the Z-Net. Seems like it is a vulnerability point.

[mterry63]

It's not a back door, and it's well documented on this forum. The Z-Net is nothing but a Raspberry Pi, and yes, there are no security patches applied regularly by HST. This has also been discussed in detail on this forum.

[DSteiNeuro]

Hmm, Bricked my Z-Net (Almost)
Ok, My Z-Net is at least 5 years old, maybe longer, so I took your advice.

I stopped HS3 from running and turned off the HS3 Computer.
I opened up my trusty Z-Net, found the microSD card and copied the contents to a folder on my PC.
I also made an image using win32diskimager (2 copies).

Ok everything going ok.
I put everything back together and plugged the Z-Net back in.
Nothing, DOA, no lights, nothing on the LAN port,

Turned out the power supply was dead,
Like we all do, I have a million micro USB power supplies lying around. Swapped it out and an back in business.
I found that my biggest failure point over the years has been power supplies.

Maybe an omen?

DSteiNeuro

[SteveW]

WTF? There's an SSH back door to the Z-Net???!!!

It would have been kinda nice if they had provided a "Power Down" button on the web UI, but I no longer expect that level of accommodation from the HS UI designers.

I'm also somewhat concerned about installing security patches to the Z-Net. Seems like it is a vulnerability point.

1) SSH is simply the UNIX / Linux "secure shell" tool used to remotely administer a machine, or locally administer a headless computer. It's encrypted, and it can be enabled or disabled via running the sudo raspi-config utility. MS Windows 10 now has a built-in SSH client; open a Windows command prompt shell, and type, for example, ssh homeseer@192.168... (IP address of the Z-Net/ Pi) and then enter the password.

2) As close as you can get to a power off button is in the HS4 web GUI: Tools-->Linux-->Shutdown system (or one of the other displayed options). Do keep in mind that this shuts down the operating system and everything running on it. but it can't physically power off a Raspberry Pi. You need to unplug the power to do that, after shutting down.

See my screenshots.

[SeattleDavid]

Sure, I know all of this.

1) I am shocked/surprised that HS leaves open this SSH back door. I realize it is "only" ssh, but it is, um, a pretty vulnerable security risk. What a juicy target for somebody that has gotten into your system. I would have expected or thought that by default this would be closed...or at a very very minimum would be well documented with the unity and not "documented" in some forum posting somewhere. This is not a safe computing design.


2) I am also quite surprised that HS didn't put a "Shutdown" button on the web page. But I do realize that it would have taken 30 minutes of somebody's time to write it *and* actually other to test that it worked.


Basic point: This is another example of how HS is rather insensitive to their customers and real-world product use.

Imagine if you purchased a device such as an Apple TV or a toaster-oven with an app and it had SSH access sitting wide open, and this wasn't clearly documented, and the manufacturer just said: it was mentioned in a posting on our forums. This would be considered to be egregiously bad product design.

Finally, The Shutdown screen you are showing is inapplicable to Z-Net. It would have been nice to have something similar on Z-Net, but it wasn't provided.

[zwolfpack]

1) I am shocked/surprised that HS leaves open this SSH back door.

I'm surprised you didn't mention the wide open administrative web interface (including the wireless LAN password). Though a fix for this is "on the todo list" ... LOL!

[SteveW]

Finally, The Shutdown screen you are showing is inapplicable to Z-Net. It would have been nice to have something similar on Z-Net, but it wasn't provided.

The Z-Net was simply a Raspberry Pi running HS3 or HS4. The menu items I posted are a screenshot of HS4 running on my Hometroller Pi, which is the current name of the product. If your menus look different, then you are probably looking at HS3.

It's always best practice to change a system's default password during or right after installation. As long as you select a complex password, SSH is not a security exposure. It uses the same password. The large majority of UNIX/Linux systems in the world are remotely managed via SSH, since they live in datacenter racks with no consoles. If it bothers you, then disable it.

RE: security (operating system) patches, this is a perfect example of a use for SSH, if you don't want to hook up a monitor and keyboard to the Pi. At the Linux command line:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get autoclean

[zwolfpack]

The Z-Net was simply a Raspberry Pi running HS3 or HS4.

Not correct. Z-Net the same hardware-wise as the HSx-Pi, but doesn't run HS3/HS4. It runs ser2net to implement the network-to-serial link, a cheezy PHP web application for administration, and a couple of miscellaneous scripts to implement things like the find.homeseer.com registration.

[SteveW]

Not correct. Z-Net the same hardware-wise as the HSx-Pi, but doesn't run HS3/HS4. It runs ser2net to implement the network-to-serial link, a cheezy PHP web application for administration, and a couple of miscellaneous scripts to implement things like the find.homeseer.com registration.

Hunh. I didn't know that. Well, I am glad their Raspberry Pi product now runs "proper HS4". Thanks.