Thin Client replacement

Hello,
we're looking to replace the expensive, virus-ridden, wall mounted "Thin
Client" Windows computers with something cheap and safe. The tasks are:
- IP address over DHCP
- some terminal windows (to telnet into an ancient mainframe)
- web browser
- no network connections accepted from the outside
After power up and afterwards, the predefined applications must come up
automatically. No login should be neccessary, and no user action should be
required to open or move any windows around. Web browser and terminal
windows should restart and connect to predefined addresses if closed by
accident.
As this device will be running 24/7 in an industrial production environment,
worst-case maintenance must be a single power cycle to bring a crashed
system up again.
I'm familiar with running a Debian/dwm desktop system.
Any suggestions on how to go about this?
**Daniel
robert
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Robert Latest
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Rasberry Pi or Beagle Bone Black should be able to do all you need. You can restrict things as much as you want in Linux. OK, power cycling crashed Linux systems is not the best for file system integrity. On the other hand, if you get rid of all unneccesary tasks, they ought to run for many months at a time.
Jon
Reply to
Jon Elson
Tick, trivial
Tick, trivial
Tick, trivial
Tick, but a little more of a firewall setup challenge
Tick, trivial
No login should be neccessary, Tick, trivial
? Not sure what you expect to move the windows if the user doesn't.
Mmm. possible but less simple. A watchdog script in a timer?
Mm. Some judicious use of read-only file systems may be indicated. OR you might run it all in a virtual machine so that 'restore from snapshot' is an option
Id personally go with Mint and probably Mate or XFCE as a staring point, after deciding what partitions to create and whether or note read only is the way to mount them
Then start to build up eh parts bit by bit.
I would imagine a startup script could be inserted into teh init.d system to, after the window manager stars up launch what apps in what window arrangements are desirable
It been a long time, but I think you can set command line options somehow top preconfigure where and what size the windows ill be.
It may be, and I am way over my pay grade here, that you dont need a window manager at all, but could just launch the apps into X-space. That way there is no window manager to resolve etc etc.
Watchdog uses `ps` to ID what apps are running and restart them if they crash
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Reply to
The Natural Philosopher
It's not clear to me if you are still wanting the Pi to be a thin client or not.
There are several pre-canned raspberry pi thin client solutions, some free, some charge a license fee.
One key issue is if you expect to play video. If so, you will need a solution like citrix which traps the mpeg stream at the server, and pipes that across for decoding in the hardware codecs on the Pi. If you can make do without video, then you have lots more options.
If you want to run directly on the Pi, terminal windows are no problem. Modern web browser is too big to run with any performance. Some of the cut-down browsers will perform better, but will not provide a modern experience, will not handle some web sites properly, and will feel old.
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Andrew Gabriel
..but easy to check: run nmap from any other host that can see the screen with the -pn option. When it sees nothing then you've got all ports blocked from accepting outside connection requests.
... ish. Would be more reliable with the filing system on a hard drive or an SSD than an SD card because both are somewhat harder to corrupt by pulling the plug than an SD card is. Search previous history on this newsgroup for threads about that. If you have a suitable 24x7 server you can connect to and keep data on, that may be the best place to put the flatscreen's filing system. You can use nfs or some other remote FS, e.g. Samba, to mount it once the flatscreen device has booted off a local read- only filing system.
Indeed, though if you want to put more than one full-screen window on the display that could be problematic no matter what OS and applications you run. Bit see my last point for more detail
Agreed, but it may combine with my next point.
Yep.
Yes, that would work, and you could use frequently executed cron jobs to detect that some application has fallen over and restart it, emailing yo an alarm if it fails more than 'n' times in a row.
If you use a systemd based system, e.g. current Raspbian versions on a RaspberryPi, then you can use a set of systemd services to (a) start everything yo need at boot time and (b) to restart anything that fails
That may be simpler that using an rc.init script plus a set of cron scripts, particularly as the old SystemVinit system is only present in systemd installations to allow daemons that haven't yet been ported to systemd to be run.
That will depend on the individual application and, to a lesser extent, on whatever window manager you're using.
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martin@   | Martin Gregorie 
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Martin Gregorie
On 2017 May 19 17:57:36, you wrote to Adrian Caspersz:
TP> Hardware aint the problem.
TP> Its the software config
especially considering that they're "thin clients" which effectively means that they are loading into VMs which apparently lack administrative maintenance and have been infested with PUPs and other unwanted nasties... sure, the hardware is clean but that software image is ganked... it shouldn't be that hard to clean them... no harder than cleaning a real machine with a real OS load...
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Reply to
mark lewis
My thought actually is, does one need a window manager at all?
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Reply to
The Natural Philosopher
....
Am I missing something here? What's wrong with each task being wrapped in a trivial shell script that loops forever, eg:
while true; do xterm -e ssh myhost; mail root -s 'ssh exited'
Reply to
Mike Scott
Hmm. You are assuming it crashes in a way that will exit back to that?
When we did watchdogs in milspec stuff it tended to be within the app, write a number that increments every time you write it, outside the app (under timer interrupt) if the number doesnt get updated for n seconds, destroy the process and recreate it. (or in many cases reboot the whole embedded system)
That takes care of 'hung' processes as well
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Reply to
The Natural Philosopher
I'm assuming the OP wants a fixed layout, eg browser window full height on the left, then two terminal windows stacked on the right.
Something like that is doable without a window manager, but the problem then becomes how to switch focus from one window to another. I don't think you can do that without a window manager.
It's probably a case of carefully selecting a window manager that allows launching of apps to particular sizes, and pinning of windows so they won't move. Or one that has a 'tile windows' function that tiles them into approximately the right layout.
Theo
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Theo
A tiling WM (such as dwm) would probably be the best bet; or you could disable moving/resizing on a normal WM, and perhaps use wmctrl to put the windows in specific places.
Reply to
Roger Bell_West
Ratpoison? (Kills all mice)
Ah, you have confirmed that I was somewhat above my pay level...yes. Keyboard focus and the like...
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Reply to
The Natural Philosopher
we run around 12 PIs since more than 2 years 24/365. First with a normal image, since last year with a ro rasbian. Have a copy of the sd card and a problem with the card / FS is no problem. Before we use EEEPCs for this task.
The PIs are cups servers for printers and do a ssh with ssh_keys and get a terminal programm for some information and for managing the print queues.
They are no thin clients.
Juergen
Reply to
Juergen Schroeder
Me scratches head. How come the existing thin client machines got viruses? They should have no direct route themselves to the internet!
Android TV boxes are also cheap, and have fast GPUs....
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Adrian C
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Adrian Caspersz
Maybe that's why the replacements are not going to.
Hardware aint the problem.
Its the software config
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Reply to
The Natural Philosopher
Many of them come rooted so you can get them to run a standard linux with a bit of Android on the side without too much trouble.
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Reply to
Ahem A Rivet's Shot
When I was involved, it was.
Thin client boxes from the likes of HP are ridiculously expensive for what they are. I pulled multiple 100's out of a nationwide office deployment, these t5145 VIA Eden 500 MHz things had 512MB of ram and a GPU that visibly couldn't move GUI drawn structures fast enough. Scrolling was a joke, even on good network bandwidth.
The t5565 replacements built on Intel Atom something had better graphics, 1GB of memory. Users complemented the better responsiveness,
But in the end we got fed up, and replaced them all with Windows 7 mini PCs. Destroyed the Citrix terminal server farm, sat the PCs all on authentication servers and migrated most of the office apps out on to the google cloud.
Based on my experience looking at rendering speeds in a web browser, I don't think the RPi (graphics/network) is fast enough to do a remote desktop service, let alone anything more fancy.
Maybe it doesn't matter for the application, if not full desktop.
...
BTW I have 40 t5145 thin clients doing nothing, thought it would make a nice linux standalone minimal feature machine with potential for marketing to hobbyists. This guy had a similar evangelicalism.
formatting link

Then someone went and launched the Raspberry Pi.....
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Adrian C
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Adrian Caspersz
was paying near that for wyse terminals back in the day..
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Reply to
The Natural Philosopher
Sure, but Wyse terminals, especially the paper-white Wy160, were a class act.
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martin@   | Martin Gregorie 
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Reply to
Martin Gregorie
All I am saying is that 150 a desktop is good value.
It is generally reckoned to keep a WinPC desktop supported and up to
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The Natural Philosopher

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