16 ms·

Making a Linux home server sleep on idle and wake on demand – the simple way

671 points by danieg 3y ago

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otterpro 3y ago
I have servers that I don't want to run 24/7 but I still need to access them from time to time. My current solution was to schedule shutdown of all the servers between 12am - 6am (usingcron) and start them up at 6am (using BIOS scheduled power-on), to save on electricity cost since no one uses them during those hours. However, this is much elegant solution.
mkopec 3y ago
Interesting. I believe with runtime (opportunistic) S0ix on x86 we'd be able to get similarly low power consumption at idle, but that would require cooperation from all devices and system firmware. It's already a thing on laptops, where if certain conditions are met, the laptop can technically be "sleeping" when the screen is displaying static content, like a document.
jacooper 3y ago
You can do this inside caddy https://github.com/dulli/caddy-wol https://github.com/dulli/caddy-wol
pmontra 3y ago
I'm using a smart plug that I can turn on via curl from a script of from its web server from my phone. However sleep to RAM has some advantage. I already entered the wake on demand rabbit hole and stopped at the first hurdles. Maybe I'll try again with the experience of this post.
heywire 3y ago
Another option, if your needs are relatively modest, is to choose a low power mini PC. The one I chose idles at around 5W under Linux before any tweaking. It is based on the Intel N5105. I have a few 2.5” external HDDs attached for backup which are configured to sleep after a short time.
- trustingtrust 3y ago
  A lot of times I want to build something on my homeserver and N5105 ain’t gonna cut it. I don’t build every day or every hour but if I want to I would have to turn it on and off every time.
- oneshtein 3y ago
  Another option is to use a smartphone with damaged screen, USB Ethernet card and an external USB drive.
  - CraigJPerry 3y ago
    This was always attractive to me, how are you running a linux host on the phone or are you just using native android hosted services?
    - oneshtein 3y ago
      I use a custom firmware with Termux. It's enough for me. https://medium.com/junior-dev/how-to-re-purpose-your-old-android-phone-by-running-linux-on-it-1310df46b3fe https://medium.com/junior-dev/how-to-re-purpose-your-old-and...
      - CraigJPerry 3y ago
        That looks good enough for me, thanks!
        oneshtein 3y ago
        Don't forget to turn on option "Don't turn screen off when charging". Use a less powerful charger to power the smartphone. 5 Watt charger is enough. 2.5 Watt may work too.
dddddaviddddd 3y ago
For the second always-on machine, a router running OpenWRT would be ideal since it would always be up anyways.
- prettyStandard 3y ago
  My thoughts exactly. This seems to be the killer app for openwrt/ddwrt.
- neilv 3y ago
  And if it's doing the routing, it can also be smarter about detecting demand for the server, and even validate that it's legitimate demand. Related discussion 14 days ago: https://news.ycombinator.com/item?id=35447094 https://news.ycombinator.com/item?id=35447094
fractalnetworks 3y ago
[flagged]
- Art9681 3y ago
  Got a link or something for me to reference? I have built a few micro itx home servers and have always wondered what a vertically integrated home solution would look like. I've been working on the custom software control plane for it for about 2 years now and gone through several permutations. I run a private cloud with these over mesh vpn and for personal use the cost cannot be beat.
- lopkeny12ko 3y ago
  Don't take advantage of someone's passion project to self-promote/advertise your product.
snthd 3y ago
I'm seeing dark text on a dark background in the diagrams (Firefox Nightly with Dark theme). Toggling dark mode to light mode to dark mode on the site's built in control "fixes" it.
NetOpWibby 3y ago
This is most excellent, just in time for my Turing Pi.
ladyanita22 3y ago
Saying Windows has had it since Windows 98 and then, acknowledging that the issue is wake-on-demand is a bit confusing to say the least. Obviously Linux can sleep easily since decades ago. The issue is wake on demand (and I don't know if Windows has that even) Edit: I don't why everyone's having issues. I run Fedora on a cheap Gigabyte G5KD and never had any problems. Never did with either of my thinkpads or my Xiaomi Mi Notebook...
- VWWHFSfQ 3y ago
  > Obviously Linux can sleep easily since decades ago. Yeah right. Suspend and resume is still buggy as hell. Power management in general in Linux is still awful after all these years.
  - mtizim 3y ago
    I have no idea how it looks on the dev/setup side, but suspend and resume is definitely a solved problem, seeing that I've never had any problems with it on my Steam Deck
    - xeyownt 3y ago
      It's very likely designed for that use case so not very relevant. Most PC are delivered with Windows, and even though Linux works on them, it's unlikely the PC were designed with suspend stability as criteria.
      - ladyanita22 3y ago
        If that's the case, who's to fault here? Linux or buggy ACPI states implemented in the motherboards?
  - xeyownt 3y ago
    I Confirm this. For years I use suspend on my laptop with latest Debian, and it's very difficult to have an uptime higher than 15 days. Every now and then, the logging in freezes to death on wake-up and requires hard power off.
throw0101a 3y ago
The concept of "ARP Stand-in" brought to mind Proxy ARP: * https://en.wikipedia.org/wiki/Proxy_ARP https://en.wikipedia.org/wiki/Proxy_ARP
- horsawlarway 3y ago
  Yup - really a nifty way to handle exposing services. I use MetalLB locally, and it does exactly this for its layer-2 mode: https://metallb.universe.tf/concepts/layer2/ https://metallb.universe.tf/concepts/layer2/ Makes for a great little load-balancer setup on bare metal k8s. I have to lose a LOT of machines all at once for anything to go down and stay down, and my router configs use a known ipv4 address for everything, without having to care at all about which machine is actually handling it.
- addingnumbers 3y ago
  Proxy ARP would have the raspberry pi provide its own MAC address as the MAC for the server IP. All the traffic from the clients to the backup server would have to pass through the Pi's network interface for the duration of the session. With this ARP stand-in, it provides the server's MAC to the client so subsequent traffic to the server doesn't need to pass through the Pi.
HankB99 3y ago
Diagrams are just visible enough that I can tell that they're present but I cannot otherwise see them. I suppose that's because I'm using a dark theme on Firefox. Not that it matters. There's enough text to figure out what's going on in the first place and it would not help me much in any case. I have a file server running of an ancient server motherboard from another age. (Supermicro X8SIL w/X3460 and 16GB ECC RAM) It uses just about 95W idle and bumps to about 150W when the drives (5 HDDs) are being scrubbed. I tried suspending the server and power dropped to about 75W - not a huge saving. Another concern is drive longevity. Starting and stopping repeatedly during the day is a lot harder on them than running continuously and could lead to premature drive failure. I could explore this if my server were SSD based but it is not.
- cmeacham98 3y ago
  I'm not using any dark theme addons or similar, just the standard prefers-color-scheme, and I have the same problem. So they just didn't account for their website's dark mode when writing the article.
  - themaninthedark 3y ago
    Windows dark theme here and I had the same problem. I clicked the light mode on the website and then back to dark mode and it was fixed. So their website is reading your theme and adjusting the background correctly but fails to adjust the test and diagrams.
  - notRobot 3y ago
    Highlighting the diagram makes it readable.
  - danieg 3y ago
    Author here, apologies for the dark mode issue and thanks for flagging it -- looks to be an open bug in theme-ui (https://github.com/system-ui/theme-ui/issues/1602 https://github.com/system-ui/theme-ui/issues/1602). I've just pushed a workaround that appears to have fixed it.
crizzlenizzle 3y ago
> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use I wish more people would care about IPv6.
- zbrozek 3y ago
  Seems unlikely. The world has made its peace with NAT, and IPv4 is simpler and therefore easier to understand. IPv6 isn't happening.
  - slashdev 3y ago
    Or is it just happening extremely slowly? I don't think we can count IPv6 out yet.
    - zbrozek 3y ago
      I hope you're right, if only so that cgNAT goes away someday. But I'm pessimistic on that front. cgNAT is too easy and works just well enough to make adopting something better too low a priority to ever happen.
  - 2bluesc 3y ago
    Roughly 40% (and rising) of Google users use IPv6. https://www.google.com/intl/en/ipv6/statistics.html https://www.google.com/intl/en/ipv6/statistics.html
    - petepete 3y ago
      Without realising and without having had to set it up themselves.
      - tzs 3y ago
        So? The vast majority of IPv4 users also do not realize and did not have to set it up themselves.
no_time 3y ago
I wonder how many sleep/wake cycles would it take a day to outweigh the TCO decrease of the power bill with the TCO increase of the increased stress/amortization of the hardware, especially HDDs.
- unnouinceput 3y ago
  Probably they use SSD's, not HDD. So no hardware stress.
- tfvlrue 3y ago
  Probably a lot. My anecdata: I have had four Seagate HDDs in my desktop PC since 2007 and despite a couple of remapped sectors, they're still working fine. I often power it on and off 1-2 times a day, and the drives are set to spin down when not in use. The SMART data for these drives shows approximately 37,000 power on hours and 17,000 start/stop cycles. That's about 4 years 3 months of actual power on time, and about 3 power cycles per year over the past 16 years. The spec sheet says these drives use 8W idle. So: 192 months - 51 months = 141 months of non-use 141 months * 0.730 kilohours / month = 102.93 kilohours 102.93 kilohours * 32 watts = 3293.76 kwh Assuming 15 cents per kwh, that comes to $494 saved by shutting the drives down over the past 16 years. And I paid $232 total for the drives back in 2007. Obviously YMMV, just thought it would be fun to calculate :)
  - usr1106 3y ago
    That might possibly be close where you live, but not where I live. I need to heat my home at least 8 months a year and I heat using electricity (which isn't the smartest thing to do, but that's the way the house was built 30 years ago). It is too hot inside less than 4 weeks a year. So saving energy is done by trying to live in cooler rooms, but not by searching for small consumers.
    - tfvlrue 3y ago
      I'm curious if you mean the 15 cents per kwh estimate is too high or too low? It's a conservative average for me in upstate NY over the past ~15 years. If you're using electric resistance heat, then I suppose a running computer is kind of like processing power plus "free" heat :)
patrickk 3y ago
Another option is to control a power-hungry NAS with a PiKVM device. It can be a cheap Pi Nano device for example. Got the idea from this youtuber[1], he has some nice ideas on setting up a home server. [1] https://www.youtube.com/watch?v=f5jNJDaztqk&t=395s https://www.youtube.com/watch?v=f5jNJDaztqk&t=395s [2] https://pikvm.org/ https://pikvm.org/
aljarry 3y ago
I had similar idea, but in the end I've gone a different path: I've got a USFF PC with 2 external HDDs as NAS, and raspberry pi to keep always on stuff. I used to keep the PC up most of the day, and get it to sleep on schedule during night with `rtcwake`, and it was pretty reliable. I've removed the scheduled sleep from the PC, as I prefer backups to be done at night, and my "minilab" of USFF PC with SSD & 2 external HDDs, rpi 4 with SSD and a 1Gb switch uses 18W idle, according to cheap power mater. USFF PC is ThinkCentre tiny m93p with 2-core 4th-gen i5, and I guess newer models should fare better with idle power use.
- fy20 3y ago
  How reliable is the external drive route? Do you run in RAID or similar?
  - aljarry 3y ago
    I've got 2 external HDDs in ZFS mirror, cheap consumer disks. One of them is perfectly fine, second one started having occasional read or write errors, which is not great. With regular weekly scrub I hadn't had any data issues over last 3 years, and I'm pretty happy with the setup. But it's a hit or miss with consumer external HDDs - before that, I used a single external HDD for backups at a time (100-200GB writes a week) and I lost data from 2 cheap external HDDs over span of 3 years.
DCKing 3y ago
This looks like one of those home server infrastructure setup rabbit holes I would've bailed out of within the first 10 minutes of Googling to research the problem. I commend the author for their perseverance and the writeup - rabbit hole writeups are their own form of entertainment. That alone was worth it. I could never run anything that looks like such a conceptual pain the butt. A pain to maintain and troubleshoot to boot. Especially since the setup requires a Raspberry Pi to run permanently. A Raspberry Pi that itself would work just as fine as the Time Machine server the author seems to need on demand?
- ttanev 3y ago
  My solution to the "10 years old PC used as a backup target" was to just donate/sell-off-as-parts the old PC, and replace with a 10 year old laptop, with an external USB enclosure. From 180-200 Watts down to 10-25, but it was not as much fun with two weeks of a rabbit whole digging :)
- louwrentius 3y ago
  I’m using A Raspberry Pi4 as a dedicated Timemachine backup server with an SSD via USB3. Works perfectly for a year or so.
- dolmen 3y ago
  However that requires the disk used for backup storage to also be always on.
  - aequitas 3y ago
    Disk have power modes and can be spun down to save energy. A Raspberry Pi can run the OS on an SD card and mount the disk for backup storage. Leaving it in low power for a long period of time.
    - nwb99 3y ago
      I'm worried about the wear on my drives spinning up and down so much? Maybe it isn't such a big deal. It is the most stressful time for spinning drives, though.
vrglvrglvrgl 3y ago
[dead]
lloydatkinson 3y ago
> Enable wake-on-LAN with unicast packets (not just magic packets) I didn't know there was more than one type of WOL packet?
- IshKebab 3y ago
  There's not really such a thing as a "WOL packet" exactly. Basically the network interface accepts any old packet, and then maybe wakes up depending on the content of the packet. You can configure it to wake up if it sees any packet (what he did). The problem is networks are rarely completely silent and your machine will just wake up randomly. Which is why they invented "MagicPacket(tm)" which is just any old packet that happens to contain a specific repeated byte pattern. The network card will wake up on any packet that happens to contain that pattern (which shouldn't happen randomly). I don't know why he didn't use MagicPacket, even though he mentioned the problem it solves.
  - 0x457 3y ago
    He explained why: he wanted the server to wake just when someone is tried to SSH to it.
    - IshKebab 3y ago
      Ah yes you are right. I definitely would have done it via some kind of gateway.
bioemerl 3y ago
So, fun story. I've got an "AI" server which has three P40s and a M40 in it. I'm doing my own version of "off while idle". I discovered that if the server gets hard shutdown by killing the power it will automatically start back up when the power turns on. As a result I just set up home assistant with a power toggle and when I want the server off or on I can start it up by restoring the power. Way more brute force than this guy's solution, but hey, it works.
- cesarb 3y ago
  > I discovered that if the server gets hard shutdown by killing the power it will automatically start back up when the power turns on. That's usually a configuration option in the BIOS setup screen, what to do on power loss: "Last state" or "Off", and your server probably has it configured as "Last state".
- counttheforks 3y ago
  https://www.home-assistant.io/integrations/wake_on_lan/ https://www.home-assistant.io/integrations/wake_on_lan/ and https://www.home-assistant.io/integrations/shell_command/ https://www.home-assistant.io/integrations/shell_command/ with `ssh server poweroff` if you want something a bit less risky measure the power draw from your smart plug when the machine is on & off, then use that to set up https://www.home-assistant.io/integrations/switch.template/ https://www.home-assistant.io/integrations/switch.template/ which combines all of this
  - bioemerl 3y ago
    Oh man, that shell command is awesome. I could set it up to run some of the services I have to manually do from my phone right now. Thanks for that information.
cesarb 3y ago
This reminds me of back when Apple sold WiFi access points (they were high-quality, but a pain to administer since they required running a Windows-only or a MacOS-only executable). I tried running arpwatch for a while on a network which had one of these, and gave up, since the MAC address for any Apple machine on the network was constantly bouncing between the real machine and the access point. Apparently, whenever an Apple desktop went to sleep, that WiFi access point proxied ARP and mDNS requests for it, much like what's described on this post (but it did that by default, with no configuration required to enable it).
- Qerub 3y ago
  For the record; you were observing the behavior of Apple's Bonjour Sleep Proxy: https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy
- deltarholamda 3y ago
  They were high-quality. I used one for years, even had a hard drive attached for a while for Time Machine backups, which worked well. I had to stop using it for some reason--it wasn't getting updates, or newer WiFi cards weren't working well with it, something--and everything I've used since has been disappointing. Even at the price point of the AirPort, they all have various issues. I wish this technology was a done thing.
adezxc 3y ago
Thank you for posting this, I saw something similar but about having a homeserver to run Jellyfin and lost it. Bookmarked this and will implement this in the future.
LaputanMachine 3y ago
Very nice, I didn't know that you could wake computers with unicast packets. For my use case, I run a Raspberry Pi that is on the same local network as my PC. When I connect to the Pi to forward my PC's RDP port to my laptop's loopback interface, the Pi sends a normal magic packet to wake my PC. All that was needed was an entry like this in my laptop's .ssh/config: Host remote-desktop HostName raspberry-pi User pi Port 1234 IdentityFile ~/.ssh/raspberry-pi-key LocalForward 3389 my-pc.local:3389 SessionType default RemoteCommand wakeonlan -i 192.168.178.255 11:22:33:44:55:66; cat Each time the RDP port is forwarded, the wakeonlan command is run on the Raspberry Pi. The 'cat' at the end keeps the command from exiting so that the RDP port keeps being forwarded. (I also configured the NOPASSWD option for wakeonlan in /etc/sudoers so that no root privileges are needed to run it.)
- t0astbread 3y ago
  There's also the "exec" keyword that lets you run a command in a "Match" block like so: Match host my-pc.local exec "wakeonlan -i 192.168.178.255 11:22:33:44:55:66" This doesn't cover the case when the connecting machine is in another network but it does avoid a hop. Perhaps you could also run another SSH command in the exec condition that connects to the Pi and has it send the WoL packet.
  - LaputanMachine 3y ago
    Thanks, this could be useful if I decide to set up a VPN in the future.
xyst 3y ago
> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use This makes me kind of sad. Even if it’s just for a private/local usage. IPv6 has the features of ARP built in via “neighborhood discovery protocol” (NDP) with the addition of various security to prevent spoofing.
- ranting-moth 3y ago
  I thought you could run IPv4 and IPv6 at the same time, or am I missing something?
  - paco3346 3y ago
    You can but the issue is that if the caller _thinks_ it can reach it over IPv6 it'll never send the IPv4 unicast packet which means the server won't wake.
  - zekica 3y ago
    Yes, and you can do the same for IPv6 using any ND proxy server.
- calcifer 3y ago
  The OP relies on ARP spoofing, so I don't think NDP would work.
moffkalast 3y ago
> You'll need: An always-on Linux device on the same network as your server, e.g. a Raspberry Pi > First, a bit about my hardware, as this solution is somewhat hardware-dependent: HP ProDesk 600 G3 SFF I seriously doubt any of this can be gotten to work on a Pi in a way that actually reduces power usage in any notable way. Hell the Pi 4 uses almost full idle current when completely powered off unless you turn off just about everything that would make it possible to wake up again without a full power cycle. And even then the draw remains significant.
- kortex 3y ago
  Many people who would do this sort of thing likely already have an always-on pi (pi-hole, dns, ssh jump box, etc). And even at full bore, pi 4 is about 6.5W, so 90% savings over the HP. https://www.pidramble.com/wiki/benchmarks/power-consumption https://www.pidramble.com/wiki/benchmarks/power-consumption
  - moffkalast 3y ago
    Ah I think I misunderstood the idea, I thought they were saying you could also use a Pi as the suspended server. That makes more sense I guess.
tzs 3y ago
> To prevent unwanted wake-ups, you'll need to ensure no device on the network is sending extraneous packets to the server Assume the home network is using 10.0.x addresses. I wonder if it would be useful to put the server on 10.1.x, add a virtual ethernet interface to the RPi that is also on 10.1.x, and configure the RPi to route between 10.0.x and 10.1.x. Configure the RPi to drop any extraneous packets directed to 10.1.x from 10.0.x. On the Mac "route add -net 10.1.0.0/16 Rpi" and add a name and the server's IP to /etc/hosts. With that approach you might also make it so the RPi runs a script whenever something tried to make a TCP connection to the server, and that script could deal with telling the server to wake. That way you can choose a wake method for the server without having to worry about whether or not other things on the network might accidentally trigger it.
- IshKebab 3y ago
  I don't know why he didn't just use magicpackets to solve that problem. That's the whole reason they exist.
graiz 3y ago
Somehow "the simple way" being a persistent Pi with a custom script seems like it's not exactly that simple. What you're trying to do is something so basic and yet I've been unable to get this setup on my NAS either. Would a static mapping of the ARP work? I'd want the server to WOL and work with timemachine without external dependancies.
unnouinceput 3y ago
If you're involving an RPi in this, in order to save power, might as well just have the RPi be the main driving force behind everything. Flip a switch to power on the server, command the backup once a custom app on server informs the RPi that server is ready, shutdown the server again by setting the above switch to OFF. This way your server will not even consume those idle watts when waiting for wake packets.
SoftTalker 3y ago
I just let my computer run all the time. Disable all sleep functionality except monitor sleep. Then it always works when I need it to. My life is way too short to fool around with stuff like this to save $5 in electricity and have to deal with the inevitiable "won't wake up" or "wakes up in a brain-damaged state" situations.
- netsharc 3y ago
  I've used Suspend-to-RAM for years on Windows, and it's always worked reliably, rarely needed fooling around with...
  - colordrops 3y ago
    Try to control it remotely with SSH and wake-on-lan. Not so reliable.
    - ttanev 3y ago
      It is not as hard, but requires a device in the middle to send the magic packets from time to time. Using my home desktop like this for years, 10 years ago it was a native feature of my tomato based router back then. Today it is with a small script that sshes into the openwrt router and sends the magic packet to the PC, but very similar in terms of UX.
- laweijfmvo 3y ago
  I'm tempted to do this as well, given the likelihood of everything working if/when my linux desktop (or laptop) actually wakes up is about 50/50 these days.
- TechBro8615 3y ago
  I do this too. I'm on a Mac and use an app called "Amphetamine" to keep the machine active (it's the successor to "Caffeine" IIRC). However, I dim the screen to black when I go to sleep, since it's the only component that can't really "idle" - it's consuming power as long as it's displaying pixels, and thus it would also be the first component to die from overuse even while "idling."
wkdneidbwf 3y ago
this is the kind of thing you spend so much time setting up and then it just stops working weeks or months later. i would never attempt to do something like this without automation. talk about a maintenance nightmare as the underlying system changes.
- IshKebab 3y ago
  I agree. WoL is not very reliable in the first place, and adding ARP spoofing into the mix just makes it even more unreliable. Would have made more sense to use the Pi as a gateway and to turn the PC on using the power button.
nikp123 3y ago
I've already made this into a all-in-one program: https://github.com/nikp123/wake-on-arp/ https://github.com/nikp123/wake-on-arp/ but i do agree with the others in this thread, it's quite a hassle to keep this setup working as intended. I'd advise against wherever possible, consider investing into an efficient PC: My current home server thing runs at only 22W while idle and costed me (including storage and networking) about 150eur. But if it's done for the fun of it, I have nothing against it.
PaulKeeble 3y ago
This feels like the sort of functionality that ought to just work now. Its a clearly useful thing for PCs all over the planet and it would be nice if they just went to sleep almost completely when idle and woke up on network or USB/PS2 input. The power savings would be enormous. Yet today I still have issues with power saving features, performance is lowered by having power saving on instead of flat out and various things don't work like Keepass looses connection to my browser for my passwords and one of the USB devices that came on the motherboard crashes the entire computer on some power transitions. Its taking an awful long time for power saving features to mature. I would love to have this for my NAS/server, it has a lot of performance for when its needed but its also idle a lot. This is not the way.
- oceanplexian 3y ago
  It's not really worth it, even though I'd commend the OP for wading through the WoL stack. I have a NAS that's running 8 drives and a modern Intel CPU and it runs around 40w from the wall under load, and idles <10W with the drive spun down and CPU not doing anything. The WoL setup made more sense 5-10 years ago when power save functionality was much more primitive and drives were way less efficient.
  - Gigachad 3y ago
    It's also a solved problem for the vast majority of the population. You pay Apple or Google a few dollars a month and they handle backups for you. Those servers aren't sitting idle 99% of the time waiting for you to backup so there is no wasted power. Self hosting is fun but not the most practical option. And now iCloud has end to end encryption, there is little reason to bother doing it yourself.
    - Aerbil313 3y ago
      > a solved problem This is only because the vast majority of the population agrees that it’s a reasonable tradeoff to not bother with all the digital privacy and security stuff beyond what the defaults are and just go on with their lives. The reason behind this is that almost no one is significantly negatively affected by not being vigilant and self-hosting everything. The downside is that things like PRISM can exist and nation-states and any sufficiently powerful or skillful interested party can and do far more easily target, surveil and harm any individual they want. Again, those individuals are not your average Joe so the public doesn’t care. As long as you don’t leave the herd and stay in line, you’re safe. Personally, I didn’t give any f… about privacy until I felt there’s a good possibility US agencies can target me, due to things I would start to talk about online. Those things were not illegal neither in US nor in my country, just different ideologies from the status quo of modernity, but I knew for a fact people have been (illegally) arrested by US agencies before due to voicing similar things.[0] [0]: https://web.archive.org/web/20221203231121/https://muslimskeptic.com/2022/03/08/how-the-us-neutralizes-muslim-leaders-the-case-of-ahmed-omar-abu-ali/ https://web.archive.org/web/20221203231121/https://muslimske...
teleforce 3y ago
What would happen if after long period of inactivity the server become a “silent” device i.e. device that does not transmit traffic for extended periods of time because can result in a loss of service binding? These periods of inactivity, thus making the device effectively unreachable (for example for a WAKE-ON-LAN packet) [1]. The diagrams in the article are just gorgeous, can you share the drawing tools being used here? [1] Shortest Path Bridging Architecture guide: https://www.al-enterprise.com/-/media/assets/internet/documents/spb-architecture-tech-brief-en.pdf https://www.al-enterprise.com/-/media/assets/internet/docume...
- matthewaveryusa 3y ago
  drawings are made with https://excalidraw.com/ https://excalidraw.com/
javajosh 3y ago
Once again I get the distinct feeling that networks talk behind our back in a phylogenic tree of patois obfuscated by deep time. (Where deep time for computers is like 30 years).
t0astbread 3y ago
I'm doing something similar but in a less fancy way: I've got a Hydra server (the NixOS CI thing) set up on a potato-grade SBC with a more powerful desktop computer acting as a builder. The desktop runs a small Go program that I've written that shuts it down after ten minutes of inactivity. Wake-on-unicast for some reason always caused the desktop to start up after just a few seconds of being shut down, so I'm using magic packets. (I'm not sure what's causing this. I suspect Tailscale but I haven't really investigated it.) Hydra connects via SSH so I've added a Match block to the potato's SSH config that sends the WoL packet first: Match host desktop.local exec /bla/bla/send-wol I'm also doing full shutdowns instead of sleeping. The difference is only about ten seconds for a CI job. If the power draw during sleep turns out to be negligible, I might switch to that at some point but first, there are bigger bottlenecks to kill (like Hydra still running expensive evaluations on the potato).
KRAKRISMOTT 3y ago
Ah, a hardware assisted "serverless" architecture :)
albert_e 3y ago
In the cloud you would just call the start_instance() API method to wake up the instance on demand. Is there a way we will have mass-produced personal cloud devices that use hypervisors with a low-power consumption control plane and use standard APIs and Terraform
bfrog 3y ago
I want something like this but on a smarter router/switch that can wake my device up on certain port/packet requests going to the sleeping device. Having to setup a pi for this sort of thing seems like yet one more thing to manage
andrewshadura 3y ago
> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use You've lost me here
RobotToaster 3y ago
> I even looked at the datasheet for my network hardware, which lists ARP Offload as a feature on the front page. >The only problem? No Linux support. Wouldn't it have been simpler to buy a network card with linux ARP offload support? Or are there none?
thesnide 3y ago
While I applaud the effort, I'm really wondering about leveraging something like a ODROID HC4 and don't worry too much about the standby power consumption. I mean, I even recently purchased an old refurbished i5 enterprise mini PC that consumes about 5W in idle mode, not even standby. It makes sense as it is leveraging laptop components inside.
saltcured 3y ago
Tangentially, I remember MythTV had support for the self-scheduled variant of this. I used to have a PC with multiple HDDs hooked to the TV and antenna which would look at its own TV recording schedule and power off when it was idle and wouldn't be recording in the next hour or less. Before powering off, it would set an RTC alarm to wake 10 minutes before the next scheduled recording. Meanwhile, if I walked into the room and wanted to watch recordings while it was off, I would just press the power button let it boot up to use the onscreen UI with IR remote control. I never bothered to figure out if I could make the IR receiver behave in some standby mode to wake the PC. The next time we moved, I couldn't be bothered to set all this up again. Now we just use an old laptop and browser for streaming and a bluetooth keyboard with pointing device for "remote" control. It idles at low enough power to run 24/7 and not care, but we can also just open/close the lid as if it is a sleep switch for the media function.
kristianpaul 3y ago
Use a rock5b board with 8 cores and 16G of ram still low power 30W
__turbobrew__ 3y ago
The simple way is paying $9.99/month for 2TB of iCloud space and put your Time Machine backups there. Home labbing can be fun and a good way to learn, but if you are just trying to back up your files you cannot beat the economies of scale and reliability of cloud providers.
michael1999 3y ago
Nice writeup. It was enjoyable watching him re-invent the Apple ARP proxy solution. The first time I tried to figure out how an ssh request could wake a Mac, I was baffled. https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy
jasoneckert 3y ago
While it is easy to criticize the approach the author took to solve this particular problem (as others have done here), I must say that I appreciate well organized posts that detail a technology problem and solution. While I may not implement a similar solution, I always manage to learn something from reading them that I'll likely use when solving another problem in the future.
xnyanta 3y ago
I stopped reading when I reached the "Disable IPv6" part.
mulle_nat 3y ago
So what is the hard way ?
jmainh 3y ago
This looks useful for the solar-powered blogs out there, like the next ones. [0] solar.lowtechmagazine.com [1] solar.leo32345.com [2] louwrentius.com
trizuz 3y ago
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otterpro 3y ago

I have servers that I don't want to run 24/7 but I still need to access them from time to time. My current solution was to schedule shutdown of all the servers between 12am - 6am (usingcron) and start them up at 6am (using BIOS scheduled power-on), to save on electricity cost since no one uses them during those hours. However, this is much elegant solution.

mkopec 3y ago

Interesting. I believe with runtime (opportunistic) S0ix on x86 we'd be able to get similarly low power consumption at idle, but that would require cooperation from all devices and system firmware. It's already a thing on laptops, where if certain conditions are met, the laptop can technically be "sleeping" when the screen is displaying static content, like a document.

jacooper 3y ago

You can do this inside caddy https://github.com/dulli/caddy-wol https://github.com/dulli/caddy-wol

pmontra 3y ago

I'm using a smart plug that I can turn on via curl from a script of from its web server from my phone. However sleep to RAM has some advantage. I already entered the wake on demand rabbit hole and stopped at the first hurdles. Maybe I'll try again with the experience of this post.

heywire 3y ago

Another option, if your needs are relatively modest, is to choose a low power mini PC. The one I chose idles at around 5W under Linux before any tweaking. It is based on the Intel N5105. I have a few 2.5” external HDDs attached for backup which are configured to sleep after a short time.

trustingtrust 3y ago
A lot of times I want to build something on my homeserver and N5105 ain’t gonna cut it. I don’t build every day or every hour but if I want to I would have to turn it on and off every time.
oneshtein 3y ago
Another option is to use a smartphone with damaged screen, USB Ethernet card and an external USB drive.
- CraigJPerry 3y ago
  This was always attractive to me, how are you running a linux host on the phone or are you just using native android hosted services?
  - oneshtein 3y ago
    I use a custom firmware with Termux. It's enough for me. https://medium.com/junior-dev/how-to-re-purpose-your-old-android-phone-by-running-linux-on-it-1310df46b3fe https://medium.com/junior-dev/how-to-re-purpose-your-old-and...
    - CraigJPerry 3y ago
      That looks good enough for me, thanks!
      - oneshtein 3y ago
        Don't forget to turn on option "Don't turn screen off when charging". Use a less powerful charger to power the smartphone. 5 Watt charger is enough. 2.5 Watt may work too.

dddddaviddddd 3y ago

For the second always-on machine, a router running OpenWRT would be ideal since it would always be up anyways.

prettyStandard 3y ago
My thoughts exactly. This seems to be the killer app for openwrt/ddwrt.
neilv 3y ago
And if it's doing the routing, it can also be smarter about detecting demand for the server, and even validate that it's legitimate demand. Related discussion 14 days ago: https://news.ycombinator.com/item?id=35447094 https://news.ycombinator.com/item?id=35447094

fractalnetworks 3y ago

[flagged]

Art9681 3y ago
Got a link or something for me to reference? I have built a few micro itx home servers and have always wondered what a vertically integrated home solution would look like. I've been working on the custom software control plane for it for about 2 years now and gone through several permutations. I run a private cloud with these over mesh vpn and for personal use the cost cannot be beat.
lopkeny12ko 3y ago
Don't take advantage of someone's passion project to self-promote/advertise your product.

snthd 3y ago

I'm seeing dark text on a dark background in the diagrams (Firefox Nightly with Dark theme). Toggling dark mode to light mode to dark mode on the site's built in control "fixes" it.

NetOpWibby 3y ago

This is most excellent, just in time for my Turing Pi.

ladyanita22 3y ago

Saying Windows has had it since Windows 98 and then, acknowledging that the issue is wake-on-demand is a bit confusing to say the least. Obviously Linux can sleep easily since decades ago. The issue is wake on demand (and I don't know if Windows has that even) Edit: I don't why everyone's having issues. I run Fedora on a cheap Gigabyte G5KD and never had any problems. Never did with either of my thinkpads or my Xiaomi Mi Notebook...

VWWHFSfQ 3y ago
> Obviously Linux can sleep easily since decades ago. Yeah right. Suspend and resume is still buggy as hell. Power management in general in Linux is still awful after all these years.
- mtizim 3y ago
  I have no idea how it looks on the dev/setup side, but suspend and resume is definitely a solved problem, seeing that I've never had any problems with it on my Steam Deck
  - xeyownt 3y ago
    It's very likely designed for that use case so not very relevant. Most PC are delivered with Windows, and even though Linux works on them, it's unlikely the PC were designed with suspend stability as criteria.
    - ladyanita22 3y ago
      If that's the case, who's to fault here? Linux or buggy ACPI states implemented in the motherboards?
- xeyownt 3y ago
  I Confirm this. For years I use suspend on my laptop with latest Debian, and it's very difficult to have an uptime higher than 15 days. Every now and then, the logging in freezes to death on wake-up and requires hard power off.

throw0101a 3y ago

The concept of "ARP Stand-in" brought to mind Proxy ARP: * https://en.wikipedia.org/wiki/Proxy_ARP https://en.wikipedia.org/wiki/Proxy_ARP

horsawlarway 3y ago
Yup - really a nifty way to handle exposing services. I use MetalLB locally, and it does exactly this for its layer-2 mode: https://metallb.universe.tf/concepts/layer2/ https://metallb.universe.tf/concepts/layer2/ Makes for a great little load-balancer setup on bare metal k8s. I have to lose a LOT of machines all at once for anything to go down and stay down, and my router configs use a known ipv4 address for everything, without having to care at all about which machine is actually handling it.
addingnumbers 3y ago
Proxy ARP would have the raspberry pi provide its own MAC address as the MAC for the server IP. All the traffic from the clients to the backup server would have to pass through the Pi's network interface for the duration of the session. With this ARP stand-in, it provides the server's MAC to the client so subsequent traffic to the server doesn't need to pass through the Pi.

HankB99 3y ago

Diagrams are just visible enough that I can tell that they're present but I cannot otherwise see them. I suppose that's because I'm using a dark theme on Firefox. Not that it matters. There's enough text to figure out what's going on in the first place and it would not help me much in any case. I have a file server running of an ancient server motherboard from another age. (Supermicro X8SIL w/X3460 and 16GB ECC RAM) It uses just about 95W idle and bumps to about 150W when the drives (5 HDDs) are being scrubbed. I tried suspending the server and power dropped to about 75W - not a huge saving. Another concern is drive longevity. Starting and stopping repeatedly during the day is a lot harder on them than running continuously and could lead to premature drive failure. I could explore this if my server were SSD based but it is not.

cmeacham98 3y ago
I'm not using any dark theme addons or similar, just the standard prefers-color-scheme, and I have the same problem. So they just didn't account for their website's dark mode when writing the article.
- themaninthedark 3y ago
  Windows dark theme here and I had the same problem. I clicked the light mode on the website and then back to dark mode and it was fixed. So their website is reading your theme and adjusting the background correctly but fails to adjust the test and diagrams.
- notRobot 3y ago
  Highlighting the diagram makes it readable.
- danieg 3y ago
  Author here, apologies for the dark mode issue and thanks for flagging it -- looks to be an open bug in theme-ui (https://github.com/system-ui/theme-ui/issues/1602 https://github.com/system-ui/theme-ui/issues/1602). I've just pushed a workaround that appears to have fixed it.

crizzlenizzle 3y ago

> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use I wish more people would care about IPv6.

zbrozek 3y ago
Seems unlikely. The world has made its peace with NAT, and IPv4 is simpler and therefore easier to understand. IPv6 isn't happening.
- slashdev 3y ago
  Or is it just happening extremely slowly? I don't think we can count IPv6 out yet.
  - zbrozek 3y ago
    I hope you're right, if only so that cgNAT goes away someday. But I'm pessimistic on that front. cgNAT is too easy and works just well enough to make adopting something better too low a priority to ever happen.
- 2bluesc 3y ago
  Roughly 40% (and rising) of Google users use IPv6. https://www.google.com/intl/en/ipv6/statistics.html https://www.google.com/intl/en/ipv6/statistics.html
  - petepete 3y ago
    Without realising and without having had to set it up themselves.
    - tzs 3y ago
      So? The vast majority of IPv4 users also do not realize and did not have to set it up themselves.

no_time 3y ago

I wonder how many sleep/wake cycles would it take a day to outweigh the TCO decrease of the power bill with the TCO increase of the increased stress/amortization of the hardware, especially HDDs.

unnouinceput 3y ago
Probably they use SSD's, not HDD. So no hardware stress.
tfvlrue 3y ago
Probably a lot. My anecdata: I have had four Seagate HDDs in my desktop PC since 2007 and despite a couple of remapped sectors, they're still working fine. I often power it on and off 1-2 times a day, and the drives are set to spin down when not in use. The SMART data for these drives shows approximately 37,000 power on hours and 17,000 start/stop cycles. That's about 4 years 3 months of actual power on time, and about 3 power cycles per year over the past 16 years. The spec sheet says these drives use 8W idle. So: 192 months - 51 months = 141 months of non-use 141 months * 0.730 kilohours / month = 102.93 kilohours 102.93 kilohours * 32 watts = 3293.76 kwh Assuming 15 cents per kwh, that comes to $494 saved by shutting the drives down over the past 16 years. And I paid $232 total for the drives back in 2007. Obviously YMMV, just thought it would be fun to calculate :)
- usr1106 3y ago
  That might possibly be close where you live, but not where I live. I need to heat my home at least 8 months a year and I heat using electricity (which isn't the smartest thing to do, but that's the way the house was built 30 years ago). It is too hot inside less than 4 weeks a year. So saving energy is done by trying to live in cooler rooms, but not by searching for small consumers.
  - tfvlrue 3y ago
    I'm curious if you mean the 15 cents per kwh estimate is too high or too low? It's a conservative average for me in upstate NY over the past ~15 years. If you're using electric resistance heat, then I suppose a running computer is kind of like processing power plus "free" heat :)

patrickk 3y ago

Another option is to control a power-hungry NAS with a PiKVM device. It can be a cheap Pi Nano device for example. Got the idea from this youtuber[1], he has some nice ideas on setting up a home server. [1] https://www.youtube.com/watch?v=f5jNJDaztqk&t=395s https://www.youtube.com/watch?v=f5jNJDaztqk&t=395s [2] https://pikvm.org/ https://pikvm.org/

aljarry 3y ago

I had similar idea, but in the end I've gone a different path: I've got a USFF PC with 2 external HDDs as NAS, and raspberry pi to keep always on stuff. I used to keep the PC up most of the day, and get it to sleep on schedule during night with `rtcwake`, and it was pretty reliable. I've removed the scheduled sleep from the PC, as I prefer backups to be done at night, and my "minilab" of USFF PC with SSD & 2 external HDDs, rpi 4 with SSD and a 1Gb switch uses 18W idle, according to cheap power mater. USFF PC is ThinkCentre tiny m93p with 2-core 4th-gen i5, and I guess newer models should fare better with idle power use.

fy20 3y ago
How reliable is the external drive route? Do you run in RAID or similar?
- aljarry 3y ago
  I've got 2 external HDDs in ZFS mirror, cheap consumer disks. One of them is perfectly fine, second one started having occasional read or write errors, which is not great. With regular weekly scrub I hadn't had any data issues over last 3 years, and I'm pretty happy with the setup. But it's a hit or miss with consumer external HDDs - before that, I used a single external HDD for backups at a time (100-200GB writes a week) and I lost data from 2 cheap external HDDs over span of 3 years.

DCKing 3y ago

This looks like one of those home server infrastructure setup rabbit holes I would've bailed out of within the first 10 minutes of Googling to research the problem. I commend the author for their perseverance and the writeup - rabbit hole writeups are their own form of entertainment. That alone was worth it. I could never run anything that looks like such a conceptual pain the butt. A pain to maintain and troubleshoot to boot. Especially since the setup requires a Raspberry Pi to run permanently. A Raspberry Pi that itself would work just as fine as the Time Machine server the author seems to need on demand?

ttanev 3y ago
My solution to the "10 years old PC used as a backup target" was to just donate/sell-off-as-parts the old PC, and replace with a 10 year old laptop, with an external USB enclosure. From 180-200 Watts down to 10-25, but it was not as much fun with two weeks of a rabbit whole digging :)
louwrentius 3y ago
I’m using A Raspberry Pi4 as a dedicated Timemachine backup server with an SSD via USB3. Works perfectly for a year or so.
dolmen 3y ago
However that requires the disk used for backup storage to also be always on.
- aequitas 3y ago
  Disk have power modes and can be spun down to save energy. A Raspberry Pi can run the OS on an SD card and mount the disk for backup storage. Leaving it in low power for a long period of time.
  - nwb99 3y ago
    I'm worried about the wear on my drives spinning up and down so much? Maybe it isn't such a big deal. It is the most stressful time for spinning drives, though.

vrglvrglvrgl 3y ago

[dead]

lloydatkinson 3y ago

> Enable wake-on-LAN with unicast packets (not just magic packets) I didn't know there was more than one type of WOL packet?

IshKebab 3y ago
There's not really such a thing as a "WOL packet" exactly. Basically the network interface accepts any old packet, and then maybe wakes up depending on the content of the packet. You can configure it to wake up if it sees any packet (what he did). The problem is networks are rarely completely silent and your machine will just wake up randomly. Which is why they invented "MagicPacket(tm)" which is just any old packet that happens to contain a specific repeated byte pattern. The network card will wake up on any packet that happens to contain that pattern (which shouldn't happen randomly). I don't know why he didn't use MagicPacket, even though he mentioned the problem it solves.
- 0x457 3y ago
  He explained why: he wanted the server to wake just when someone is tried to SSH to it.
  - IshKebab 3y ago
    Ah yes you are right. I definitely would have done it via some kind of gateway.

bioemerl 3y ago

So, fun story. I've got an "AI" server which has three P40s and a M40 in it. I'm doing my own version of "off while idle". I discovered that if the server gets hard shutdown by killing the power it will automatically start back up when the power turns on. As a result I just set up home assistant with a power toggle and when I want the server off or on I can start it up by restoring the power. Way more brute force than this guy's solution, but hey, it works.

cesarb 3y ago
> I discovered that if the server gets hard shutdown by killing the power it will automatically start back up when the power turns on. That's usually a configuration option in the BIOS setup screen, what to do on power loss: "Last state" or "Off", and your server probably has it configured as "Last state".
counttheforks 3y ago
https://www.home-assistant.io/integrations/wake_on_lan/ https://www.home-assistant.io/integrations/wake_on_lan/ and https://www.home-assistant.io/integrations/shell_command/ https://www.home-assistant.io/integrations/shell_command/ with `ssh server poweroff` if you want something a bit less risky measure the power draw from your smart plug when the machine is on & off, then use that to set up https://www.home-assistant.io/integrations/switch.template/ https://www.home-assistant.io/integrations/switch.template/ which combines all of this
- bioemerl 3y ago
  Oh man, that shell command is awesome. I could set it up to run some of the services I have to manually do from my phone right now. Thanks for that information.

cesarb 3y ago

This reminds me of back when Apple sold WiFi access points (they were high-quality, but a pain to administer since they required running a Windows-only or a MacOS-only executable). I tried running arpwatch for a while on a network which had one of these, and gave up, since the MAC address for any Apple machine on the network was constantly bouncing between the real machine and the access point. Apparently, whenever an Apple desktop went to sleep, that WiFi access point proxied ARP and mDNS requests for it, much like what's described on this post (but it did that by default, with no configuration required to enable it).

Qerub 3y ago
For the record; you were observing the behavior of Apple's Bonjour Sleep Proxy: https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy
deltarholamda 3y ago
They were high-quality. I used one for years, even had a hard drive attached for a while for Time Machine backups, which worked well. I had to stop using it for some reason--it wasn't getting updates, or newer WiFi cards weren't working well with it, something--and everything I've used since has been disappointing. Even at the price point of the AirPort, they all have various issues. I wish this technology was a done thing.

adezxc 3y ago

Thank you for posting this, I saw something similar but about having a homeserver to run Jellyfin and lost it. Bookmarked this and will implement this in the future.

LaputanMachine 3y ago

Very nice, I didn't know that you could wake computers with unicast packets. For my use case, I run a Raspberry Pi that is on the same local network as my PC. When I connect to the Pi to forward my PC's RDP port to my laptop's loopback interface, the Pi sends a normal magic packet to wake my PC. All that was needed was an entry like this in my laptop's .ssh/config: Host remote-desktop HostName raspberry-pi User pi Port 1234 IdentityFile ~/.ssh/raspberry-pi-key LocalForward 3389 my-pc.local:3389 SessionType default RemoteCommand wakeonlan -i 192.168.178.255 11:22:33:44:55:66; cat Each time the RDP port is forwarded, the wakeonlan command is run on the Raspberry Pi. The 'cat' at the end keeps the command from exiting so that the RDP port keeps being forwarded. (I also configured the NOPASSWD option for wakeonlan in /etc/sudoers so that no root privileges are needed to run it.)

t0astbread 3y ago
There's also the "exec" keyword that lets you run a command in a "Match" block like so: Match host my-pc.local exec "wakeonlan -i 192.168.178.255 11:22:33:44:55:66" This doesn't cover the case when the connecting machine is in another network but it does avoid a hop. Perhaps you could also run another SSH command in the exec condition that connects to the Pi and has it send the WoL packet.
- LaputanMachine 3y ago
  Thanks, this could be useful if I decide to set up a VPN in the future.

xyst 3y ago

> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use This makes me kind of sad. Even if it’s just for a private/local usage. IPv6 has the features of ARP built in via “neighborhood discovery protocol” (NDP) with the addition of various security to prevent spoofing.

ranting-moth 3y ago
I thought you could run IPv4 and IPv6 at the same time, or am I missing something?
- paco3346 3y ago
  You can but the issue is that if the caller _thinks_ it can reach it over IPv6 it'll never send the IPv4 unicast packet which means the server won't wake.
- zekica 3y ago
  Yes, and you can do the same for IPv6 using any ND proxy server.
calcifer 3y ago
The OP relies on ARP spoofing, so I don't think NDP would work.

moffkalast 3y ago

> You'll need: An always-on Linux device on the same network as your server, e.g. a Raspberry Pi > First, a bit about my hardware, as this solution is somewhat hardware-dependent: HP ProDesk 600 G3 SFF I seriously doubt any of this can be gotten to work on a Pi in a way that actually reduces power usage in any notable way. Hell the Pi 4 uses almost full idle current when completely powered off unless you turn off just about everything that would make it possible to wake up again without a full power cycle. And even then the draw remains significant.

kortex 3y ago
Many people who would do this sort of thing likely already have an always-on pi (pi-hole, dns, ssh jump box, etc). And even at full bore, pi 4 is about 6.5W, so 90% savings over the HP. https://www.pidramble.com/wiki/benchmarks/power-consumption https://www.pidramble.com/wiki/benchmarks/power-consumption
- moffkalast 3y ago
  Ah I think I misunderstood the idea, I thought they were saying you could also use a Pi as the suspended server. That makes more sense I guess.

tzs 3y ago

> To prevent unwanted wake-ups, you'll need to ensure no device on the network is sending extraneous packets to the server Assume the home network is using 10.0.x addresses. I wonder if it would be useful to put the server on 10.1.x, add a virtual ethernet interface to the RPi that is also on 10.1.x, and configure the RPi to route between 10.0.x and 10.1.x. Configure the RPi to drop any extraneous packets directed to 10.1.x from 10.0.x. On the Mac "route add -net 10.1.0.0/16 Rpi" and add a name and the server's IP to /etc/hosts. With that approach you might also make it so the RPi runs a script whenever something tried to make a TCP connection to the server, and that script could deal with telling the server to wake. That way you can choose a wake method for the server without having to worry about whether or not other things on the network might accidentally trigger it.

IshKebab 3y ago
I don't know why he didn't just use magicpackets to solve that problem. That's the whole reason they exist.

graiz 3y ago

Somehow "the simple way" being a persistent Pi with a custom script seems like it's not exactly that simple. What you're trying to do is something so basic and yet I've been unable to get this setup on my NAS either. Would a static mapping of the ARP work? I'd want the server to WOL and work with timemachine without external dependancies.

unnouinceput 3y ago

If you're involving an RPi in this, in order to save power, might as well just have the RPi be the main driving force behind everything. Flip a switch to power on the server, command the backup once a custom app on server informs the RPi that server is ready, shutdown the server again by setting the above switch to OFF. This way your server will not even consume those idle watts when waiting for wake packets.

SoftTalker 3y ago

I just let my computer run all the time. Disable all sleep functionality except monitor sleep. Then it always works when I need it to. My life is way too short to fool around with stuff like this to save $5 in electricity and have to deal with the inevitiable "won't wake up" or "wakes up in a brain-damaged state" situations.

netsharc 3y ago
I've used Suspend-to-RAM for years on Windows, and it's always worked reliably, rarely needed fooling around with...
- colordrops 3y ago
  Try to control it remotely with SSH and wake-on-lan. Not so reliable.
  - ttanev 3y ago
    It is not as hard, but requires a device in the middle to send the magic packets from time to time. Using my home desktop like this for years, 10 years ago it was a native feature of my tomato based router back then. Today it is with a small script that sshes into the openwrt router and sends the magic packet to the PC, but very similar in terms of UX.
laweijfmvo 3y ago
I'm tempted to do this as well, given the likelihood of everything working if/when my linux desktop (or laptop) actually wakes up is about 50/50 these days.
TechBro8615 3y ago
I do this too. I'm on a Mac and use an app called "Amphetamine" to keep the machine active (it's the successor to "Caffeine" IIRC). However, I dim the screen to black when I go to sleep, since it's the only component that can't really "idle" - it's consuming power as long as it's displaying pixels, and thus it would also be the first component to die from overuse even while "idling."

wkdneidbwf 3y ago

this is the kind of thing you spend so much time setting up and then it just stops working weeks or months later. i would never attempt to do something like this without automation. talk about a maintenance nightmare as the underlying system changes.

IshKebab 3y ago
I agree. WoL is not very reliable in the first place, and adding ARP spoofing into the mix just makes it even more unreliable. Would have made more sense to use the Pi as a gateway and to turn the PC on using the power button.

nikp123 3y ago

I've already made this into a all-in-one program: https://github.com/nikp123/wake-on-arp/ https://github.com/nikp123/wake-on-arp/ but i do agree with the others in this thread, it's quite a hassle to keep this setup working as intended. I'd advise against wherever possible, consider investing into an efficient PC: My current home server thing runs at only 22W while idle and costed me (including storage and networking) about 150eur. But if it's done for the fun of it, I have nothing against it.

PaulKeeble 3y ago

This feels like the sort of functionality that ought to just work now. Its a clearly useful thing for PCs all over the planet and it would be nice if they just went to sleep almost completely when idle and woke up on network or USB/PS2 input. The power savings would be enormous. Yet today I still have issues with power saving features, performance is lowered by having power saving on instead of flat out and various things don't work like Keepass looses connection to my browser for my passwords and one of the USB devices that came on the motherboard crashes the entire computer on some power transitions. Its taking an awful long time for power saving features to mature. I would love to have this for my NAS/server, it has a lot of performance for when its needed but its also idle a lot. This is not the way.

oceanplexian 3y ago
It's not really worth it, even though I'd commend the OP for wading through the WoL stack. I have a NAS that's running 8 drives and a modern Intel CPU and it runs around 40w from the wall under load, and idles <10W with the drive spun down and CPU not doing anything. The WoL setup made more sense 5-10 years ago when power save functionality was much more primitive and drives were way less efficient.
- Gigachad 3y ago
  It's also a solved problem for the vast majority of the population. You pay Apple or Google a few dollars a month and they handle backups for you. Those servers aren't sitting idle 99% of the time waiting for you to backup so there is no wasted power. Self hosting is fun but not the most practical option. And now iCloud has end to end encryption, there is little reason to bother doing it yourself.
  - Aerbil313 3y ago
    > a solved problem This is only because the vast majority of the population agrees that it’s a reasonable tradeoff to not bother with all the digital privacy and security stuff beyond what the defaults are and just go on with their lives. The reason behind this is that almost no one is significantly negatively affected by not being vigilant and self-hosting everything. The downside is that things like PRISM can exist and nation-states and any sufficiently powerful or skillful interested party can and do far more easily target, surveil and harm any individual they want. Again, those individuals are not your average Joe so the public doesn’t care. As long as you don’t leave the herd and stay in line, you’re safe. Personally, I didn’t give any f… about privacy until I felt there’s a good possibility US agencies can target me, due to things I would start to talk about online. Those things were not illegal neither in US nor in my country, just different ideologies from the status quo of modernity, but I knew for a fact people have been (illegally) arrested by US agencies before due to voicing similar things.[0] [0]: https://web.archive.org/web/20221203231121/https://muslimskeptic.com/2022/03/08/how-the-us-neutralizes-muslim-leaders-the-case-of-ahmed-omar-abu-ali/ https://web.archive.org/web/20221203231121/https://muslimske...

teleforce 3y ago

What would happen if after long period of inactivity the server become a “silent” device i.e. device that does not transmit traffic for extended periods of time because can result in a loss of service binding? These periods of inactivity, thus making the device effectively unreachable (for example for a WAKE-ON-LAN packet) [1]. The diagrams in the article are just gorgeous, can you share the drawing tools being used here? [1] Shortest Path Bridging Architecture guide: https://www.al-enterprise.com/-/media/assets/internet/documents/spb-architecture-tech-brief-en.pdf https://www.al-enterprise.com/-/media/assets/internet/docume...

matthewaveryusa 3y ago
drawings are made with https://excalidraw.com/ https://excalidraw.com/

javajosh 3y ago

Once again I get the distinct feeling that networks talk behind our back in a phylogenic tree of patois obfuscated by deep time. (Where deep time for computers is like 30 years).

t0astbread 3y ago

I'm doing something similar but in a less fancy way: I've got a Hydra server (the NixOS CI thing) set up on a potato-grade SBC with a more powerful desktop computer acting as a builder. The desktop runs a small Go program that I've written that shuts it down after ten minutes of inactivity. Wake-on-unicast for some reason always caused the desktop to start up after just a few seconds of being shut down, so I'm using magic packets. (I'm not sure what's causing this. I suspect Tailscale but I haven't really investigated it.) Hydra connects via SSH so I've added a Match block to the potato's SSH config that sends the WoL packet first: Match host desktop.local exec /bla/bla/send-wol I'm also doing full shutdowns instead of sleeping. The difference is only about ten seconds for a CI job. If the power draw during sleep turns out to be negligible, I might switch to that at some point but first, there are bigger bottlenecks to kill (like Hydra still running expensive evaluations on the potato).

KRAKRISMOTT 3y ago

Ah, a hardware assisted "serverless" architecture :)

albert_e 3y ago

In the cloud you would just call the start_instance() API method to wake up the instance on demand. Is there a way we will have mass-produced personal cloud devices that use hypervisors with a low-power consumption control plane and use standard APIs and Terraform

bfrog 3y ago

I want something like this but on a smarter router/switch that can wake my device up on certain port/packet requests going to the sleeping device. Having to setup a pi for this sort of thing seems like yet one more thing to manage

andrewshadura 3y ago

> Disable IPv6: this approach relies on ARP, which IPv6 doesn't use You've lost me here

RobotToaster 3y ago

> I even looked at the datasheet for my network hardware, which lists ARP Offload as a feature on the front page. >The only problem? No Linux support. Wouldn't it have been simpler to buy a network card with linux ARP offload support? Or are there none?

thesnide 3y ago

While I applaud the effort, I'm really wondering about leveraging something like a ODROID HC4 and don't worry too much about the standby power consumption. I mean, I even recently purchased an old refurbished i5 enterprise mini PC that consumes about 5W in idle mode, not even standby. It makes sense as it is leveraging laptop components inside.

saltcured 3y ago

Tangentially, I remember MythTV had support for the self-scheduled variant of this. I used to have a PC with multiple HDDs hooked to the TV and antenna which would look at its own TV recording schedule and power off when it was idle and wouldn't be recording in the next hour or less. Before powering off, it would set an RTC alarm to wake 10 minutes before the next scheduled recording. Meanwhile, if I walked into the room and wanted to watch recordings while it was off, I would just press the power button let it boot up to use the onscreen UI with IR remote control. I never bothered to figure out if I could make the IR receiver behave in some standby mode to wake the PC. The next time we moved, I couldn't be bothered to set all this up again. Now we just use an old laptop and browser for streaming and a bluetooth keyboard with pointing device for "remote" control. It idles at low enough power to run 24/7 and not care, but we can also just open/close the lid as if it is a sleep switch for the media function.

kristianpaul 3y ago

Use a rock5b board with 8 cores and 16G of ram still low power 30W

__turbobrew__ 3y ago

The simple way is paying $9.99/month for 2TB of iCloud space and put your Time Machine backups there. Home labbing can be fun and a good way to learn, but if you are just trying to back up your files you cannot beat the economies of scale and reliability of cloud providers.

michael1999 3y ago

Nice writeup. It was enjoyable watching him re-invent the Apple ARP proxy solution. The first time I tried to figure out how an ssh request could wake a Mac, I was baffled. https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy https://en.wikipedia.org/wiki/Bonjour_Sleep_Proxy

jasoneckert 3y ago

While it is easy to criticize the approach the author took to solve this particular problem (as others have done here), I must say that I appreciate well organized posts that detail a technology problem and solution. While I may not implement a similar solution, I always manage to learn something from reading them that I'll likely use when solving another problem in the future.

xnyanta 3y ago

I stopped reading when I reached the "Disable IPv6" part.

mulle_nat 3y ago

So what is the hard way ?

jmainh 3y ago

This looks useful for the solar-powered blogs out there, like the next ones. [0] solar.lowtechmagazine.com [1] solar.leo32345.com [2] louwrentius.com

trizuz 3y ago

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