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I have a Debian box that is currently running headless. I am still learning about Linux and I want a way to view my desktop if the machine goes into safe mode. I would prefer something like TightVNC because it's encoding over wifi networks, but as I understand it, this seems to be be flaky, depending on the desktop environment.
Hmm, "safe mode" sounds like a Windows thing. Isn't that running run level 1, i.e. as root? Personally, when my headless server has that kind of problem, I use ssh and the command line first to investigate. If you want a desktop, any variety of VNC is ok, but so is rdesktop, with xrdp on the server. If you are in ssh, you can restart the server, or the desktop as needed. Hope that helps
Not really, as far as I know the computer will not automatically reboot into a recovery mode if an error occurs and as stated it is a command line mode. If the system crashes for some unknown reason and you can't ssh as stated above then a hard reboot is required or you might be able to recover if you can connected a monitor/keyboard.
I guess "Safe Mode" isn't the right term. Maintenance mode, maybe? Either way, I once screwed up my /fstab trying to mount a share. As such, I couldn't SSH into it. I had to hook up a monitor and keyboard, which was a royal PITA given where the server is located.
A remote serial console server, remote KVM, remote access card, or hands on 24/7 support are the primary means for getting into a server in a datacenter when things go wrong.
It sounds like you want/need something built into the hardware, like IPMI. Typically you'd buy a machine with this kind of functionality built in, but there are probably add-on cards that can do it as well. Otherwise, there are IP-based KVM systems you can use, but they aren't cheap.
As others have stated, what you're specifically asking for is serial access. If a server goes down to the point that its OS is no longer loading, then you cannot, obviously, use a tool that sits on top of an OS. Serial ports send raw data; it's what people use to get into routers and embedded systems.
Outside of that, you do have some special hardware options, like DRAC on Dell and ILO on HP, but if it's not built into your computer already, it's going to cost serious money (unless there's a budget access card out there that I don't know about).
So if I may answer your question from a different angle: this is a great case for either virtualisation or for containers. Install a stable OS on your server (personally I'd go for Slackware or CentOS, but if you're learning Debian then that works too, just keep away from Sid). Inside of that, install a virtualised instance of the OS. KVM is very good, and you can use libvirt with virt-manager to manage it, and obviously there are loads of tutorials out there for Docker, as well. Whatever you choose, this instance becomes the server that you actually use; the base install hosting that virtual server is the one that you remote into when things go horribly wrong. The advantage is that you're not mucking around with the host OS, but with the virtualised one -- and since the host OS never gets touched (aside from security updates), the chance of it falling over are slim.
That's how I would do it, any way. And since server admin'ing is all about virtualisation and containers now, you get the added bonus of being exposed to that as you learn Linux.
Maybe BIOS can be set to Serial Modem... Anyway, just another 'rat-hole' to go down...
Edit: Oh : a simple&secure ssh-only 'little old' PC, wired to server's serial port!
Now, what (if any) serial port features does YOUR bios have?
Or 'assume' grub will always be ok, then just need some 'remote reset' [tbd?]
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