I tested every IP KVM in my Homelab • Hacker News Board

Re: I tested every IP KVM in my Homelab

#51

Post by JdeBP » Fri, Jun 05, 2026, 7:42 PM UTC

gregsadetsky wrote: post #14

+1000 points for the PiKVM V4 Plus. We (Revise Robotics - a YC company!) refurbish laptops with robots and AI - as part of this, we (or rather, the AI) send(s) keyboard commands in software to the computers we're refurbishing. How/why? The AI needs to navigate the BIOS among other tasks - so we need a KVM to send arrow down and enter, roughly speaking. We were a GL.iNet KVM shop until we ran into a nasty issue with a…

I'm not from GL. I write my own USB HID handlers and I'm being nosy about bad protocol that exists in the wild. Was the 0 byte in some input report? In a descriptor? Somewhere else?

Re: I tested every IP KVM in my Homelab

#52

Post by atomicnumber3 » Fri, Jun 05, 2026, 8:06 PM UTC

noncoml wrote: post #47

gregsadetsky wrote: post #14

+1000 points for the PiKVM V4 Plus. We (Revise Robotics - a YC company!) refurbish laptops with robots and AI - as part of this, we (or rather, the AI) send(s) keyboard commands in software to the computers we're refurbishing. How/why? The AI needs to navigate the BIOS among other tasks - so we need a KVM to send arrow down and enter, roughly speaking. We were a GL.iNet KVM shop until we ran into a nasty issue with a…

$400 for kvm?

It's one of those things where $400 is WAY too much for a homelabber, but most companies (even small ones) can barely count that low when speccing out hardware, ESPECIALLY these days. $400 is like one hard drive in a machine that will potentially have 8-24 of them.

......Unsettlingly that's also like 16GB of dram in a machine that might be measuring memory in TBs

Re: I tested every IP KVM in my Homelab

#53

Post by mrsilencedogood » Fri, Jun 05, 2026, 8:10 PM UTC

ryanmcbride wrote: post #22

It will never make sense to me why KVMs are such a hard problem to solve. It seems like something we should have a good answer for by now but we still really just don't without dropping hundreds of dollars, and even then it still feels like a crap shoot.

As other comments have indicated, this is basically solved for all servers. All Poweredges and supermicros have come with increasingly sophisticated integrated remote management systems for the past 20+ years. I have some R610s and their drac is old but still quite good all things considered.

Re: I tested every IP KVM in my Homelab

#54

Post by Hamuko » Fri, Jun 05, 2026, 8:36 PM UTC

atomicnumber3 wrote: post #52

noncoml wrote: post #47

Earlier quoted context omitted.

$400 for kvm?

It's one of those things where $400 is WAY too much for a homelabber, but most companies (even small ones) can barely count that low when speccing out hardware, ESPECIALLY these days. $400 is like one hard drive in a machine that will potentially have 8-24 of them. ......Unsettlingly that's also like 16GB of dram in a machine that might be measuring memory in TBs

I kinda wanted to get a KVM recently, but decided to save my money to afford RAM for my planned server build instead. Might even get a 32 GB kit for $400.

Re: I tested every IP KVM in my Homelab

#55

Post by themafia » Fri, Jun 05, 2026, 8:51 PM UTC

blipvert wrote: post #27

ryanmcbride wrote: post #22

It will never make sense to me why KVMs are such a hard problem to solve. It seems like something we should have a good answer for by now but we still really just don't without dropping hundreds of dollars, and even then it still feels like a crap shoot.

It’s bizarre that one needs to do all this via a keyboard/monitor interface. Nearly thirty years ago when I used to work on Silicon Graphics kit everything from powering on and off a server to installing the OS from scratch over the network could be done out of band via serial - and automatically, using expect(1) That’s progress, I guess.

We used to do this. Since we had so many to manage we actually got an IP based serial port multiplexer.

https://www.digi.com/products/networking/infrastructure-mana...

The downside is you now had to ask of any Cat5 cable "is this serial or is this ethernet?"

Re: I tested every IP KVM in my Homelab

#56

Post by noncoml » Fri, Jun 05, 2026, 8:55 PM UTC

atomicnumber3 wrote: post #52

noncoml wrote: post #47

Earlier quoted context omitted.

$400 for kvm?

It's one of those things where $400 is WAY too much for a homelabber, but most companies (even small ones) can barely count that low when speccing out hardware, ESPECIALLY these days. $400 is like one hard drive in a machine that will potentially have 8-24 of them. ......Unsettlingly that's also like 16GB of dram in a machine that might be measuring memory in TBs

don't these boxes already have a BMC? KVM is kind of poor man's BMC.

Re: I tested every IP KVM in my Homelab

#57

Post by gregsadetsky » Fri, Jun 05, 2026, 9:00 PM UTC

JdeBP wrote: post #51

gregsadetsky wrote: post #14

+1000 points for the PiKVM V4 Plus. We (Revise Robotics - a YC company!) refurbish laptops with robots and AI - as part of this, we (or rather, the AI) send(s) keyboard commands in software to the computers we're refurbishing. How/why? The AI needs to navigate the BIOS among other tasks - so we need a KVM to send arrow down and enter, roughly speaking. We were a GL.iNet KVM shop until we ran into a nasty issue with a…

I'm not from GL. I write my own USB HID handlers and I'm being nosy about bad protocol that exists in the wild. Was the 0 byte in some input report? In a descriptor? Somewhere else?

TLDR - GLKVM's kernel emits a trailing 0-byte DATA packet (ZLP) (which PiKVM does not)

Supposedly, this is due to the `req->zero = ((count % maxpacket) == 0)` line in the kernel's f_hid.c - which, for 8-byte HID keyboard reports, makes it append a trailer packet. Strict BIOS HID stacks treat this 0-byte packet as malformed and beep.

Re: I tested every IP KVM in my Homelab

#58

Post by mstaoru » Fri, Jun 05, 2026, 9:03 PM UTC

Surprised nobody mentioned Intel vPro AMT so far. It is basically an always-on KVM that's part of CPU firmware, powered by an always-on 5V PSU rail. There is a scary amount of options, including unattended periodic (or alarm based) phone home, user acceptance or full user override, boot media spoofing, Serial over WiFi... All built-in into consumer(-ish) CPUs.

Re: I tested every IP KVM in my Homelab

#59

Post by McGlockenshire » Fri, Jun 05, 2026, 9:25 PM UTC

mstaoru wrote: post #58

Surprised nobody mentioned Intel vPro AMT so far. It is basically an always-on KVM that's part of CPU firmware, powered by an always-on 5V PSU rail. There is a scary amount of options, including unattended periodic (or alarm based) phone home, user acceptance or full user override, boot media spoofing, Serial over WiFi... All built-in into consumer(-ish) CPUs.

I'm not surprised that nobody noticed it at all. That's because it's not a KVM that you can purchase and test, the subject to the article.

Instead, you're just talking about IMPIjr. These specific features are not in consumer grade CPUs, but in CPUs marked for workstations. Ain't no consumer buying fuckin vPro machines. These are enterprise IT management features, not user features. They're also subject to frequent insane rants by people obsessed with them as possible privacy issues.

Re: I tested every IP KVM in my Homelab

#60

Post by fc417fc802 » Fri, Jun 05, 2026, 9:30 PM UTC

toast0 wrote: post #39

blipvert wrote: post #27

Earlier quoted context omitted.

It’s bizarre that one needs to do all this via a keyboard/monitor interface. Nearly thirty years ago when I used to work on Silicon Graphics kit everything from powering on and off a server to installing the OS from scratch over the network could be done out of band via serial - and automatically, using expect(1) That’s progress, I guess.

server ipmi includes serial over lan, which can work ... it's helpful if the console settings for early boot match the console settings for OS boot, and there's no standard for sharing them, so that's a bit of a mess... and then you have some where serial over lan drops out during boot, which is kind of terrible. :( But, the devices here are geared towards people using consumer products as servers (which I do at home…

> serial console during early boot is not an option on those

But it should be. There's really no excuse for the current state of affairs. There ought to be a standardized low level API for all this stuff. One should never need to directly attach a keyboard, mouse, and monitor in order to provision a piece of hardware.