6 ms·

One thing I’ve always wondered is why it’s not common to be able to use a laptop as a generic keyboard and monitor for another computer. For doing maintenance o

One thing I’ve always wondered is why it’s not common to be able to use a laptop as a generic keyboard and monitor for another computer. For doing maintenance on a headless machine it feels silly to go buy a keyboard and monitor when my laptop already is those.

deleted 3y ago
[deleted]
leonheld 3y ago
Everyone uses ssh to do that.
- dingnuts 3y ago
  That's a completely different use-case. SSH doesn't let me control the GUI on the remote And no, X11 forwarding is not what I mean either
  - jeffbee 3y ago
    So, you'll accept any solution, except the existing ones that work? XDMCP solves this exact issue. You use one device which becomes virtually an attached terminal of another device which is actually headless and with no input devices of its own. We've had this for 30+ years.
    - pessimizer 3y ago
      No, we already use the solutions that actually work, and are speculating why there isn't one with the simple, obvious user experience. Why shouldn't we?
    - exe34 3y ago
      > XDMCP muh wayland
      - pierat 3y ago
        I'm sure we'll see functionality like that in Wayland.... In a decade or 2.
  - bee_rider 3y ago
    There is/was a tool called x2x, which somehow let you send your input (mouse/keyboard) to another machine (I think via X forwarding tricks, although I don’t know how it worked, so I could be wrong). I tried it around a decade ago and at the time it felt a bit abandoned. I vaguely remember that it might not have worked with every window manager? Anyway, I assume it hasn’t got better supported since then. But it did feel magical.
    - ssl-3 3y ago
      x2x worked fine for input devices. Later, things like x2vnc made the idea more cross-platform (X on the local unix-like box, VNC on some other platform), but only with two machines. After that, Synergy became a thing, and supported many machines, but then they eventually went to a model that tended to require payment. Later, Barrier forked from Synergy, and it allows much of the same functionality. It's still very free, and it still works, but it's kind of abandoned. Today, there's Input Leap. It is (naturally) a fork of Barrier, and it is still sees regular development. https://github.com/input-leap/input-leap https://github.com/input-leap/input-leap
- aendruk 3y ago
  …except for when they can’t. The relevant retort would be that I could instead be using hardware with a remote management interface like IPMI, and building a custom OS installation image with remote access preconfigured. But even then I’m not sure how you’d have me troubleshoot surprise network issues.
- calamari4065 3y ago
  And what do you do when your ssh server stops working, or there's a hardware fault, a network fault, a failed OS upgrade?
  - filoleg 3y ago
    Idk about all machines ever, but I remember being able to access ssh over a serial port. Though in that specific case for me, it was more of a necessity rather than just a quirky way of using ssh (due to the “machine” just being a dev board with a UART ESP32).
    - calamari4065 3y ago
      To access the serial port remotely you need to add hardware to bridge it to the network. Or you go up to the machine and plug in another computer with a keyboard and monitor to access it directly.
ThrowawayTestr 3y ago
The inability to simply connect one computer to another has always bothered me. Apparently there's a mode in USB 4 which will allow this.
- rusk 3y ago
  RS232 null modem ftw!
  - dekhn 3y ago
    At some point in college (in the mid 90s) I had a Linux box and a Sun box (pre-solaris) and had them connected up using X11 over SLIP over RS232 with a null modem and gender changer. The sun workstation could be completely controlled through RS232- you could reset the machine, do stuff to the boot system, etc. IIRC the max baud I could use was 19200, or maybe 38400.
    - rusk 3y ago
      > The sun workstation could be completely controlled through RS232 As a terminal right? the native function for RS232 was dumb terminals, and at some point that got abstracted a few thousand times to what we consider to be common terminals. You were running a proper paleo setup!
- ssl-3 3y ago
  There was a time when FireWire did that kind of thing -- not specifically with remote displays, but providing a high-bandwidth (for the time) wired network link between two PCs. At home, in the Ye Olde 10/100 Ethernet days, sometimes I plugged my laptop into my desktop with 400Mbps FireWire to transfer big files. No special cable required; any dumb FireWire cable with the right connectors on each end ("big" for the desktop, "little" for that particular laptop) worked just fine between any two FireWire devices.
  - LoganDark 3y ago
    You talking about Target Display Mode? Or did that never support FireWire?
myself248 3y ago
Seriously. A friend of mine built a cyberdeck specifically for this -- his mouse and keyboard can be switched to an external port and then cabled to another machine, and there are two HDMI ports on the side, one output and one input, with an internal switch to select either the deck's own machine, or the external input, as the source for the deck's monitor.
- WillAdams 3y ago
  Has your friend done a write-up or parts list or build? I think this would be a big hit on Hackaday or some similar site.
  - speed_spread 3y ago
    An OrangePi 5 Plus would be a good starting platform for this because of the HDMI input port.
    - myself248 3y ago
      Oooo.
    - RockRobotRock 3y ago
      what?? Can you run PiKVM on it?
      - speed_spread 3y ago
        I didn't know about PiKVM. I have no idea if it will run. Probably not as-is.
nfriedly 3y ago
The GPD Pocket 3 has a KVM module that lets you do exactly this: it has HDMI & USB-C inputs and then it acts as a display, keyboard, and mouse for whatever machine it's connected to: https://gpd.hk/gpdpocket3 https://gpd.hk/gpdpocket3 There's also the up-and-coming Minisforum V3 tablet that has a video input so that it can act as an external monitor, but I don't think it'll be able to share it's keyboard and mouse. I agree with you, though, it really would be nice if this were a more common feature.
- bodge5000 3y ago
  Not much of a hardware guy so don't know if this is at all plausible, but it'd be nice to see that as an extension port on the framework laptops. That surely is the advantage of having modular ports. This is a fairly niche application so I can see why it's not a standard option, but for those who want it it could be a real game changer.
  - pbronez 3y ago
    That’s a neat concept. Are there any products that take a video input and USB A connection, combine into USB C and act as a KVM? I can’t even think what that would be called, TBH. It’s hard to search for.
    - Zircom 3y ago
      Something like this maybe? Can use USB C or HDMI+USB A depending https://www.amazon.com/Dopesplay-Wireless-Portable-Touchscreen-12900mAh/dp/B0CMPYNQCZ/ https://www.amazon.com/Dopesplay-Wireless-Portable-Touchscre... I've had some success searching "lapdock" as well, they're marketed towards using them with smartphones it looks like but can't see why you couldn't plug it into a server or computer as well.
      - bryanrasmussen 3y ago
        I had one of those - not that exact one, it was great but I forgot it on the train one day.
molave 3y ago
My laptop's monitor went bust and now serves as a glorified CPU.
justsomehnguy 3y ago
Costs, extremely low demand, no standard interconnect and interfaces, anything non-standard wouldn't work with dead OS, costs.
- aaronblohowiak 3y ago
  Can’t it all be acccomplished in Software with usb-c?
  - justsomehnguy 3y ago
    You still need software support for it on the host device. While you can imitate Keyboard and Mouse (and they would work through boot or without OS), Video is out of question for now. And while there is still some value on it using on a healthy system, most of the time KVM device is needed when something is not working. NB there is/was Intel ATM which provides (at least on paper and on rare, extremely rare posts on Internet) KVM-like experience and power control. Theoretically it can be used as the basis for single USB port KVM interface.
    - aaronblohowiak 3y ago
      Thanks!
RunSet 3y ago
hidclient will let your laptop pretend to be bluetooth keyboard and mouse. https://web.archive.org/web/20180610141436/http://anselm.hoffmeister.be/computer/hidclient/index.html.en https://web.archive.org/web/20180610141436/http://anselm.hof... https://github.com/benizi/hidclient https://github.com/benizi/hidclient
- boneitis 3y ago
  Thanks for posting this. It is pretty much solving a major pain point for me (as is TFA, seemingly on a brief skim), even if with some usability friction. I have a Flipper Zero and have always fantasized about having some sort of VMware/VirtualBox-like application that operates in a capture mode to forward all inputs to another device (similarly as to the guest machine in the VM player) with a keyboard shortcut to release the HIDs back to the host. In the Flipper Zero's case (or any SBC/SOC/microcontroller/whatever-term-is-appropriate), it would be so lovely to be able to operate in all four combinations of: Host - BT - Flipper - BT - Second device Host - USB - Flipper - BT - Second device Host - BT - Flipper - USB - Second device Host - USB/GPIO - Flipper - USB/GPIO - Second device Unfortunately, I don't work so close to the hardware, so I've no idea where to even begin with this. A man can dream. Sigh.
deleted 3y ago
[deleted]
mrb 3y ago
As someone who often deals with headless machines, the best solution I have found for using my laptop as a monitor is this: https://www.amazon.com/dp/B0BJ2YDV7Q https://www.amazon.com/dp/B0BJ2YDV7Q It's basically a chip to capture the HDMI signal from a headless machine, and expose an emulated webcam via USB to your laptop. It's so tiny the electronic is basically built into the cable. For the keyboard I haven't found a good solution other than buying a standard wireless keyboard (with integrated trackpad, for the rare cases where a mouse is needed).
- RCitronsBroker 3y ago
  Thats genius
- btgeekboy 3y ago
  That's basically what I do as well. I combined a similar HDMI dongle with a Logitech K400 Plus wireless keyboard+trackpad combo. It's an absolutely terrible membrane keyboard for everyday use, but having the trackpad and keyboard in the same device, using the same single dongle that has a storage slot in the keyboard makes things really easy for light, occasional use.
- bryanrasmussen 3y ago
  So if you have a broken monitor on your M1 with this can you use it on your other laptop? Because my broken M1 has a working keyboard.
- rfoo 3y ago
  For the keyboard I use a CH340+CH9329 cable, the former is a USB to UART converter and the latter is a UART to USB-HID converter. Feels unnecessarily complicated but hey at least it's only $3. It's effectively a USB "keyboard" controlled by another host. Then I use a ~30 line Python script to forward key press to it. I really hope someone make a better integrated solution (or me having time to do it), though.
  - hipjiveguy 3y ago
    do you have a link to the cable you use, and what's your python script? Thanks!
guenthert 3y ago
Oh me too, but that's now quite a few years ago. These days we have IPMI, no?
- aendruk 3y ago
  You can deduce the answer by charitably interpreting that the situations in which I’m attaching a keyboard and monitor are those in which that’s a reasonable action.

deleted 3y ago

[deleted]

leonheld 3y ago

Everyone uses ssh to do that.

dingnuts 3y ago
That's a completely different use-case. SSH doesn't let me control the GUI on the remote And no, X11 forwarding is not what I mean either
- jeffbee 3y ago
  So, you'll accept any solution, except the existing ones that work? XDMCP solves this exact issue. You use one device which becomes virtually an attached terminal of another device which is actually headless and with no input devices of its own. We've had this for 30+ years.
  - pessimizer 3y ago
    No, we already use the solutions that actually work, and are speculating why there isn't one with the simple, obvious user experience. Why shouldn't we?
  - exe34 3y ago
    > XDMCP muh wayland
    - pierat 3y ago
      I'm sure we'll see functionality like that in Wayland.... In a decade or 2.
- bee_rider 3y ago
  There is/was a tool called x2x, which somehow let you send your input (mouse/keyboard) to another machine (I think via X forwarding tricks, although I don’t know how it worked, so I could be wrong). I tried it around a decade ago and at the time it felt a bit abandoned. I vaguely remember that it might not have worked with every window manager? Anyway, I assume it hasn’t got better supported since then. But it did feel magical.
  - ssl-3 3y ago
    x2x worked fine for input devices. Later, things like x2vnc made the idea more cross-platform (X on the local unix-like box, VNC on some other platform), but only with two machines. After that, Synergy became a thing, and supported many machines, but then they eventually went to a model that tended to require payment. Later, Barrier forked from Synergy, and it allows much of the same functionality. It's still very free, and it still works, but it's kind of abandoned. Today, there's Input Leap. It is (naturally) a fork of Barrier, and it is still sees regular development. https://github.com/input-leap/input-leap https://github.com/input-leap/input-leap
aendruk 3y ago
…except for when they can’t. The relevant retort would be that I could instead be using hardware with a remote management interface like IPMI, and building a custom OS installation image with remote access preconfigured. But even then I’m not sure how you’d have me troubleshoot surprise network issues.
calamari4065 3y ago
And what do you do when your ssh server stops working, or there's a hardware fault, a network fault, a failed OS upgrade?
- filoleg 3y ago
  Idk about all machines ever, but I remember being able to access ssh over a serial port. Though in that specific case for me, it was more of a necessity rather than just a quirky way of using ssh (due to the “machine” just being a dev board with a UART ESP32).
  - calamari4065 3y ago
    To access the serial port remotely you need to add hardware to bridge it to the network. Or you go up to the machine and plug in another computer with a keyboard and monitor to access it directly.

ThrowawayTestr 3y ago

The inability to simply connect one computer to another has always bothered me. Apparently there's a mode in USB 4 which will allow this.

rusk 3y ago
RS232 null modem ftw!
- dekhn 3y ago
  At some point in college (in the mid 90s) I had a Linux box and a Sun box (pre-solaris) and had them connected up using X11 over SLIP over RS232 with a null modem and gender changer. The sun workstation could be completely controlled through RS232- you could reset the machine, do stuff to the boot system, etc. IIRC the max baud I could use was 19200, or maybe 38400.
  - rusk 3y ago
    > The sun workstation could be completely controlled through RS232 As a terminal right? the native function for RS232 was dumb terminals, and at some point that got abstracted a few thousand times to what we consider to be common terminals. You were running a proper paleo setup!
ssl-3 3y ago
There was a time when FireWire did that kind of thing -- not specifically with remote displays, but providing a high-bandwidth (for the time) wired network link between two PCs. At home, in the Ye Olde 10/100 Ethernet days, sometimes I plugged my laptop into my desktop with 400Mbps FireWire to transfer big files. No special cable required; any dumb FireWire cable with the right connectors on each end ("big" for the desktop, "little" for that particular laptop) worked just fine between any two FireWire devices.
- LoganDark 3y ago
  You talking about Target Display Mode? Or did that never support FireWire?

myself248 3y ago

Seriously. A friend of mine built a cyberdeck specifically for this -- his mouse and keyboard can be switched to an external port and then cabled to another machine, and there are two HDMI ports on the side, one output and one input, with an internal switch to select either the deck's own machine, or the external input, as the source for the deck's monitor.

WillAdams 3y ago
Has your friend done a write-up or parts list or build? I think this would be a big hit on Hackaday or some similar site.
- speed_spread 3y ago
  An OrangePi 5 Plus would be a good starting platform for this because of the HDMI input port.
  - myself248 3y ago
    Oooo.
  - RockRobotRock 3y ago
    what?? Can you run PiKVM on it?
    - speed_spread 3y ago
      I didn't know about PiKVM. I have no idea if it will run. Probably not as-is.

nfriedly 3y ago

The GPD Pocket 3 has a KVM module that lets you do exactly this: it has HDMI & USB-C inputs and then it acts as a display, keyboard, and mouse for whatever machine it's connected to: https://gpd.hk/gpdpocket3 https://gpd.hk/gpdpocket3 There's also the up-and-coming Minisforum V3 tablet that has a video input so that it can act as an external monitor, but I don't think it'll be able to share it's keyboard and mouse. I agree with you, though, it really would be nice if this were a more common feature.

bodge5000 3y ago
Not much of a hardware guy so don't know if this is at all plausible, but it'd be nice to see that as an extension port on the framework laptops. That surely is the advantage of having modular ports. This is a fairly niche application so I can see why it's not a standard option, but for those who want it it could be a real game changer.
- pbronez 3y ago
  That’s a neat concept. Are there any products that take a video input and USB A connection, combine into USB C and act as a KVM? I can’t even think what that would be called, TBH. It’s hard to search for.
  - Zircom 3y ago
    Something like this maybe? Can use USB C or HDMI+USB A depending https://www.amazon.com/Dopesplay-Wireless-Portable-Touchscreen-12900mAh/dp/B0CMPYNQCZ/ https://www.amazon.com/Dopesplay-Wireless-Portable-Touchscre... I've had some success searching "lapdock" as well, they're marketed towards using them with smartphones it looks like but can't see why you couldn't plug it into a server or computer as well.
    - bryanrasmussen 3y ago
      I had one of those - not that exact one, it was great but I forgot it on the train one day.

molave 3y ago

My laptop's monitor went bust and now serves as a glorified CPU.

justsomehnguy 3y ago

Costs, extremely low demand, no standard interconnect and interfaces, anything non-standard wouldn't work with dead OS, costs.

aaronblohowiak 3y ago
Can’t it all be acccomplished in Software with usb-c?
- justsomehnguy 3y ago
  You still need software support for it on the host device. While you can imitate Keyboard and Mouse (and they would work through boot or without OS), Video is out of question for now. And while there is still some value on it using on a healthy system, most of the time KVM device is needed when something is not working. NB there is/was Intel ATM which provides (at least on paper and on rare, extremely rare posts on Internet) KVM-like experience and power control. Theoretically it can be used as the basis for single USB port KVM interface.
  - aaronblohowiak 3y ago
    Thanks!

RunSet 3y ago

hidclient will let your laptop pretend to be bluetooth keyboard and mouse. https://web.archive.org/web/20180610141436/http://anselm.hoffmeister.be/computer/hidclient/index.html.en https://web.archive.org/web/20180610141436/http://anselm.hof... https://github.com/benizi/hidclient https://github.com/benizi/hidclient

boneitis 3y ago
Thanks for posting this. It is pretty much solving a major pain point for me (as is TFA, seemingly on a brief skim), even if with some usability friction. I have a Flipper Zero and have always fantasized about having some sort of VMware/VirtualBox-like application that operates in a capture mode to forward all inputs to another device (similarly as to the guest machine in the VM player) with a keyboard shortcut to release the HIDs back to the host. In the Flipper Zero's case (or any SBC/SOC/microcontroller/whatever-term-is-appropriate), it would be so lovely to be able to operate in all four combinations of: Host - BT - Flipper - BT - Second device Host - USB - Flipper - BT - Second device Host - BT - Flipper - USB - Second device Host - USB/GPIO - Flipper - USB/GPIO - Second device Unfortunately, I don't work so close to the hardware, so I've no idea where to even begin with this. A man can dream. Sigh.

deleted 3y ago

[deleted]

mrb 3y ago

As someone who often deals with headless machines, the best solution I have found for using my laptop as a monitor is this: https://www.amazon.com/dp/B0BJ2YDV7Q https://www.amazon.com/dp/B0BJ2YDV7Q It's basically a chip to capture the HDMI signal from a headless machine, and expose an emulated webcam via USB to your laptop. It's so tiny the electronic is basically built into the cable. For the keyboard I haven't found a good solution other than buying a standard wireless keyboard (with integrated trackpad, for the rare cases where a mouse is needed).

RCitronsBroker 3y ago
Thats genius
btgeekboy 3y ago
That's basically what I do as well. I combined a similar HDMI dongle with a Logitech K400 Plus wireless keyboard+trackpad combo. It's an absolutely terrible membrane keyboard for everyday use, but having the trackpad and keyboard in the same device, using the same single dongle that has a storage slot in the keyboard makes things really easy for light, occasional use.
bryanrasmussen 3y ago
So if you have a broken monitor on your M1 with this can you use it on your other laptop? Because my broken M1 has a working keyboard.
rfoo 3y ago
For the keyboard I use a CH340+CH9329 cable, the former is a USB to UART converter and the latter is a UART to USB-HID converter. Feels unnecessarily complicated but hey at least it's only $3. It's effectively a USB "keyboard" controlled by another host. Then I use a ~30 line Python script to forward key press to it. I really hope someone make a better integrated solution (or me having time to do it), though.
- hipjiveguy 3y ago
  do you have a link to the cable you use, and what's your python script? Thanks!

guenthert 3y ago

Oh me too, but that's now quite a few years ago. These days we have IPMI, no?

aendruk 3y ago
You can deduce the answer by charitably interpreting that the situations in which I’m attaching a keyboard and monitor are those in which that’s a reasonable action.