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Ask Slashdot: Hardware for Headless Linux Boxes 180

Alan Hodgkinson asks: "I would like to setup a bunch of Linux boxes without keyboards and monitors. The systems must be accessable/controlable via their serial ports, including the ability to send them a hard reset. Sun Sparc hardware has this feature. You can remove the keyboard and the system will boot and send all its console output through the serial port. You can even reset the machine by sending a break to the serial port. Is there any hardware available for PCs that will provides this functionality? (And that works on a wide variety of PC hardware). ISPs must face this problem. What do they do? Tips anyone?"
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Ask slashdot: Hardware for Headless Linux Boxes

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  • by Anonymous Coward

    The problem is most likely the cable. I have a 4 port omnicube with a 21" sony screen, and I don't notice any distortion between directly connecting the monitor to my machine or having it go through the kvm. The reason is that I use ultraspec It's $35 for ONE HD15 cable (I had to get 5 of them). I've tried just about every brand, and I've never seen better quality cables. They're also the most expensive ones around, so I guess you get what you pay for. The omnicube supports up to 1600x1200 btw.
  • by Anonymous Coward on Thursday June 17, 1999 @10:07AM (#1845705)
    Ok, so we're the poor bastards who came up with this and are building it. As some of you were able to figure out, that's a PS/2 keyboard port on the back of the board meant to jumper to the PC keyboard port..

    So what started as a couple of guys needing a decent way to manage cheap fast hardware in their webservers, seems to have turned into a small tornado of interest... I don't know who told who and how it got to slashdot. We were hoping to keep a lid on this until it was finished....

    Present status is that it's basically functional but has some rough edges and needs some 'usability' help... The coding and design has been taking a back seat to 'real work' because there are bills to pay... This is sadly still the case so try not to lean on us too hard please..

    Herb. A dumb name for a dumb answer to a really dumb question.
  • Quite right... I distinctly recall (though it's not right in front of me in the moment) that the 2.2 kernel allows for a serial console.
  • Posted by Fleeno:

    All you need is a machine that doesn't care that it doesn't have a video card or keyboard. I have several machines like this, they complain a little, but boot regardless.

    You can then use the "console on serial port" option in your kernel or just connect via your network.
  • There are some newer motherboards that don't need a keyboard to boot. I've done it.

    Get your fresh, hot kernels right here []!
  • a good place to start is to look on ebay, inside the computers/terminals section.

  • If you have two linux machines next to each other, what you can do is use null modems to connect the serial ports togather. For resets, you can wire a relay to the parrell port and the reset contacts on the motherboard. When one needs a reboot log into the other and execute the commands to do so.

    Of course with as stable as linux is, you will probably forget you have that ability, spend 2 weeks trying to remember where the broken machine is, and then reboot it from the console.

  • . I'm pretty sure you can do the opposite, and telnet to the box to access it's ports. What? You mean that people use terminal servers for other then accessing consoles? We have several 64 port terminal servers in out lab, nearly all the equipment we have has a serial port on that is connected in turn to a terminal server so we can telnet to the console.

    We build our own hardware, and let me assure you that working serial port consoles are first on the agenda for those who write the prom code. We can't imangine debugging without printfs that go directly to this serial port. (Yes, we have heard of source level kernel debuggers. We have been paying $$$ for them for a few years. rumor has it that two weeks ago someone finially got it working.) Even if we did have debuggers, the serial port is the perfect place to controll things when your network hub dies (the hub is built in so that several processors can talk via ethernet internally. Or at least that is an explination I think the NDA allows me to give)

    In short, you can use a terminal server to access console ports. I didn't know they were used for anything else.

  • After talking to someone at Cybex, they said the 4XP (the modular one that will do Sun, et al) will support higher bandwidth, while the smaller Autoview (the one we own) will not. Either way, I think Cybex products are great!

  • You should compile your kernel with support for a
    serial console. Then add a getty line to your /etc/inittab to run a getty on the tty line. You should also modify your lilo.conf to enable the console on a serial line.

    I was playing with this a few days ago, but my
    old terminal blew up on me!

    Also, if you want to reset the machine by sending break, you have to do a little kernel modification in /usr/src/linux/drivers/char/serial.c. The current code will generate a SIGINT signal to the foreground process group if a break is sent. (If the BRKINT termios option is enabled, and IGNBRK is not enabled). There is also support for the break signal to act as the SAK (secure attention key). It shouldn't be too hard to force a reboot if a break is received. I don't think that you can reboot the machine from within an interrupt context, but you could wake up a ``watchdog'' process which will do the reboot. Add an ioctl() which causes the calling process to block indefinitely. When a break is received, wake up the process. Then write a userland process that opens the tty, calls the ioctl and then reboots the machine if the ioctl returns with a successful error code. This is largely trivial to write, since the code for handling break is already there.

    The ioctl could be wrapped up in a tiny tool which is then used in a shell script that runs /sbin/shutdown:

    if shutdown_watcher /dev/ttyS0 ; then
    /sbin/shutdown -r now

    Of course, if the machine is too hosed to reboot, this obviously won't work. A hardware solution is required that turns the break signal into a hard reset.
  • Can't you just connect a couple of serial port pins to the reset switch?
  • You can probably get one for free. Try universities, businesses, or government offices. They give 'em away all the time when they upgrade old hardware.
  • It's actually pretty easy to support this, if you have the right hardware. I support roughly 100 Linux/x86 servers spread across the US, and hardware makes a big difference.

    First, by and large, remote rebooting doesn't matter as much as you might expect. Over the last year, we've only had 5 or so actual lockups in remote locations. Generally, under Linux, when something dies, it's dead, with a total hardware failure. For the most part, power supplies and hard drives are to blame, although we've lost a motherboard or two. Avoid cheap drives and power supplies -- Seagate Barracudas work almost flawlessly for us. Frankly, we've had more problems with spontanous reboots that hard lockups.

    If you're paranoid (we are :-), and want to do things right, then the first thing to look at are Intel's server boards. We use the T440BX and the N440BX (single/dual P2 boards). They both support serial consoles in the BIOS, they have built in SCSI, Ethernet, and VGA, they have a on-board hardware watchdog, they have excellent hardware monitoring built-in, and they support remote reboot/power-off/power-on, if you can figure out the protocol to use. I have a driver for 2.2 that supports quite a few of the monitoring/management features of the board. Mail me for info.


  • Most BIOSes I've seen have an option to turn that off. Look for a "Keyboard Installed" option.

    The ones that don't tend to be more recent, and also tend to autodetect that the keyboard is missing and deal with it.

    I've set up several headless servers this way. Granted, it was a pain when I needed to play in the BIOS, but at other times, it worked out fine.
  • The Netwinder ( supports headless operation. If there's no keyboard detected, the Firmware (equiv. to x86 BIOS) will switch to the serial port. Of course, Netwinders are rather more expensive than low-end x86 boxes, so this may not help you.

    I don't think it's possible to do a hard reset from the serial port, but there might be some way to add this. I believe the Netwinder also has a hardware watchdog timer, which would remove some of the need for a reset line.

    (My Netwinder runs headless, but it's within arm's reach of my desk so I haven't had to worry about remote resetting).

    As others have mentioned, compile in serial-console support in the kernel, and make sure that your /dev/console has the correct device numbers (or make it a symlink to ttyS0).

  • the insight manager remote access card..

    it's actually a complete 386 on a card. It's operating system agnostic so it'll work fine with linux.

    In fact it will work better with linux than with NT as the card can only capture text mode screen's - not much use with NT.. but perfect for linux/*bsd/sco.
  • Turn on serial console, and use something like a Cisco 2511 as a terminal server. For the remote reboot stuff, you can simply use the above link and get telnet-able power control. Pretty neato.

    You can have a logging machine connect to each serial port of each server via the 2511 and use that for logging the console information. So whomever says that you cannot get all the boot info from a linux box remotely was very wrong.

    Good luck
  • Why don't you look for CabltCube (neato bleue Cubes that run linux on a R4000n processor -,) They come with serial control (then you'll just need to tweak the Kernel). They do just what you want. more info can be found @ []
    Can also take a look @ endebed systems from motorola - but linux dev on those cutties is SLOW []
  • (sorry I didn't read all the answers, may be
    someone already pointed that out).


    some guys from compaq showed us a card which
    was designed for their pc servers. it allows
    distant administration using a modem, and redirects all bios output to a comm port.
    it also saves the last page of text in case
    of reboot (useful for bsod).
    I don't know if it is NT only stuff (I mean
    the card was plugged into an NT server, could
    there be specific drivers for it, or is it just
    bypassing the OS ?) .
    Price was about 6000 French Francs (that should
    be around $1000 -- or less)
  • I recall seeing one of my older boxen boot without a keyboard.

    "Press to continue"

    I thought it was a bad joke, but in retrospect, I suppose you could send it any old key press through a serial port.

  • > the next problem is what to do with all the
    > serial cables? I hav no idea! Maybe there are
    > some type of hub...

    What you need is a terminal server - we have a bunch of (now idle) Chase IOLan ( rack boxes that take 16 serial ports each and turn them into telnet connections (we used to use them to handle dial in from individual modems for PPP before things like the Ascend Max and the Portmaster existed). I'm pretty sure you can do the opposite, and telnet to the box to access it's ports. You certainly can on some equivalent boxes (Xylogics Annexe, Equinoxe etc...). They are probably pretty cheap to pick up now. We paid about $1300 each for ours, but that was a few years ago now.

    Warning: "High-speed" (>19200bps) sucks a bit on the Chase. The older boxes in general have pretty crummy UARTs, since they were designed to handle 16 vt100/wyse terminal sessions, not 16 simultaneous 33600 downloads.
  • Umm, yes - they are (were originally) used as comms servers for terminals :-)

    Plug your 64 telesales staff into your unix ordering system from their vt100's? Wire up your college terminal room so that users have access to a generic telnet prompt to access your hosts?
  • My only problem with my Omniview Pro 8 that I use to control the 6 machines under my desk, is that after switching around, when I get back to the one win95 machine, I have to redetect the mouse to get the scroll wheel on my logitech cordless to work again. Other than that, it's alot nicer than the old 6 port AT keyboard/serial mouse only box I used before.

    Although, the PROM on the SGI Visual Workstations lets you use a serial console to change settings and such. X flys on the 320's too, even though the server isn't accelerated yet. At the last MDLUG meeting, they had one up and running Linux, with GNOME and all the eyecandy turned on, like transparency and such. Even dragging windows around didn't slow it down...
  • The ISP I run uses a Rose Electronics KVM (Keyboard, Video, Mouse) switch... It lets us control a bunch of different Linux (an one NT) boxen with one mouse, keyboard and monitor. This works better in my opinion than the serial solution cause you can get X as well as console.
  • I admin servers in New Jersey and San Francisco. I am in Ohio. We have a portmaster 2 terminal server on the net we can telnet to, then get a serial based login prompt to the machines. The suns talk to the serial from the very beginning. You can get what equates to the BIOS setup screen over the serial. No octopus monitor switch does that for you. And no monitor switch helps you if you're in Ohio and the machine is in New Jersey. New Intel Dual PII/III boards have a bios feature that puts the info out a serial, just like the suns. This may be the Phoenix Bios that others have talked about. A friend has several of these. over a serial connection, the machine boots and you can enter the bios screen. You can get a lilo prompt. That's the kind of control you need over remote machines.
  • I work for a mid-size ISP and we use switch boxes. Make sure to spend the money on a digital switch box as you will soon find yourself very unhappy with the analog ones.

    The 'console on serial port' option in the 2.2.x kernels is most likely a cheaper route. And do you really need the three-finger salute when you have /sbin/shutdown?

    And if you really need to power-cycle a machine, maybe look into the SNMP-manageable power strips.
  • you also need to get lilo to yammer on the serial port. see the lilo docs for more info.
  • I run several linux boxes headless with console output redirected to the serial port. Currently both of these boxes are using 2.0.35 with the serial console patch. Both have bioses that allow booting with no video or keyboard, but on one box Linux (the kernel) will not boot unless a keyboard is present, regardless of the bios setting.

    Searches of dejanews and the kernel archive revealed (paraphrased) "yes, this has been seen before". I recall finding reference to a patch, but I either could not get it to work, or could not find the patch.

    I am sure I tried and failed with a 2.1.xx kernel, but the box with trouble went into use long before 2.2 came out, and I have not bothered to upgrade it to test if it boots correctly without a keyboard because: It currently works fine; a trip would be required to disconnect the keyboard plugged into it.

    I did find for sale "keyboard simulators", basically terminators to plug into the keyboard socket, but they were much more expensive than an actual keyboard.

    Also, be careful with the switchbox solution. The more expensive switchboxes simulate the presence of a keyboard, mouse, monitor, etc., even when switched away from that box. However, the cheaper switchboxes do no simulation, and just have a switch with no fancy electronics. The cheap ones often work fine, though.

    The moral? It might be worthwhile to test your headless setup on a prototype box, before investing in a whole set of boxes that will have issues.

    BTW: My Psion S5 makes the best portable vt100 I have used. Palm Pilots can also work, but the keyboard on the S5 gives it a big advantage over the Pilots for actual work, as opposed to just monitoring output.

  • I would like one ... if I can get one cheap. Having used exclusively PC's I know absolutely nothing about terminals and would like to learn ...
  • by kiowa ( 5743 )
    Well, to boot a system without the keyboard
    or/and display hooked up is dependant on the
    specific BIOS the motherboard uses.

    Usually you can just find an option that says
    "ignore errors" or something like it, you'll
    know when you see it. ;)

  • It is worth noting that there is now an (unsupported) patch to get VMS 7.2 going on the once 'NT only' Multia workstation. This had been rumoured to be floating around at Digital for a long time...but DEC was so far up MS's...err, well, anyway.

    Compaq has (sorta) corrected this problem. They were kind enough to provide VMS for hobbyists for free and recently extended that to the most recent version (7.2) and to Alpha, and to most of the layered products (DEC Compilers! Yay!) Unfortunately they still want ridiculous sums if you want to use it for business.

    There are links on there to the Montagar site, and from there you should be able to find media kits and the driver patches if you're at all interested. There are also 2 or 3 commercial products from other manufacturers participating in the hobbyist licensing...I highly recommend Multinet as a TCP/IP stack. Derived from BSD/Tahoe ...very nice management tools.

  • Are you involved in the NetBSD project? Just wondering.

    Great to see a local company doing some really cool stuff. I was once a customer. Neat!
  • I have a similar box, it it old k75 o/c to k90 (mobo doesn't support 50 bus) on via pa-2011 (ami bios). I control it over network (ssh), but i guess you can go serial way if you wish. For it to boot without monitor, you have to change display option from VGA to NONE in Bios. be sure to remove the video card, it will not work with card in there. Regarding the keyboard, remove the option "HALT on keyboard error" from bios. That should get you to boot up, from there on it should be simple.
  • Speaking as someone who has worked for an ISP, I'm going to disagree with you. SSH/Telnet access is BY NO MEANS a substitute for console access (although it's obviously useful in it's own right).

    We had a couple of machines located in London, about 60 miles from our office, and having console access via a terminal server saved several trips to London - and if you've ever tried to drive in London, you'll appreciate how important that is :-)

    Of course, those machines were Sun boxes, where that sort of thing is trivial. But this new Phoenix BIOS sounds like it might the answer to a lot of prayers.
  • Are your boxes going to be plugged into any sort of network? If so, why do you need a terminal; I run headless boxes all the time with no keyboard that I control entirely from a ssh or telnet connection.

    You can even dump syslog to another box if you require.

    Also, remember a serial port is just another tty (ttyS*). Therefore, you can plug a terminal into it and not worry about the local tty's.

    And if rebooting is important, you can always ssh in and reboot. If the box crashes you'll have to yank the power regardless, so you could easily build a box that has a switch for each computer; flip the switch to kill the power.

    A little bit of hacking-but isn't that what linux is about?
  • This is not what I was pointing out. It seems that this fellow is not doing that. And besides, a box with a terminal plugged into the serial port is still not going to boot with a wanky kernel.

    I could not imagine 18 terminals for 18 servers either; I prefer to telnet to all of my shells. Especially since a lot of the boxes I look after are cities away.

    Welcome to a PC world in which every advertisment for a new computer features "It is soooo easy."

  • Correct me if I'm wrong, but aren't serial consoles handled by inittab? I've run terminals off of a serial port since 2.0.34 till now. The kernel has never had any effect, as long as I had serial support in the kernel.

    Why would you only want a serial console? Does it make that much difference to be running getty? I've never thought so. Besides, this way if the box dies you can pull it off the shelf and put a keyboard and monitor onto it and fix 'er up.
  • It is possible with the latest kernels to redirect the console to a tty at boot time. It can be made to do this manually or automatically. See "CONFIG_SERIAL_CONSOLE" in /usr/src/linux/Documentation/ for information. You will have to install and configure your boxes normally, but after that you can set them up to do what you want with this option. Also, make sure that your boxes have a BIOS that allows you to disable keyboard checking at power up.
  • Yes, it's imperative to add inline suppressors if you have a box that is prone to doing this. Some boxes send 'break like signals' when you power them off as well. (grr!)

  • The best solution we ever found was -

    1) recompile linux (2.1+) kernel to 'use serial port as console' which means if you boot sans video card you get a serial console.

    2) set mobo for 'ignore errors on boot'

    3) use an APC powerstrip with serial and telnet access to powering on/off outlets individually

    4) use a portmaster connected to all the serial ports and the APC.

    dialback only modem access into the portmaster as well as network access

    Most of the sites we set up were colo sites, or in locked secure server rooms so remote access was a boon.

    Any questions?
  • NT has nothing to do with it. The card needs a 'wake on lan' feature (ie: intel 100 managed). When it sees a 'magic packet' (a packet addressed to it's MAC with the contents being it's MAC repeated 16 times) the card triggers the ATX motherboard.
  • I own a ServSwitch (made by Black Box), and they
    can use either the normal cables or special coax
    cables. The coax ones go pretty far (up to 100
    feet, I think). I have a 20 ft cable connecting
    the machine to the switchbox, and a 10 ft cable
    that goes from the switchbox to the monitor.

    I run my system at 1280x1024 and 1600x1200, and
    I haven't had any problems with video distortion
    or anything like that.

    Black Box says that the coax reduces the noise,
    and to me it looks like that it does indeed make a


    p.s. I don't work for Black Box or anything like
    that, I just figured someone might find this
  • We (VA Research) have EMP working under Linux as I type. Full BIOS and Console redirection, full access to hardware event logs, power control, sensors, etc...but...its just not quite finished. Soon. Yes, it will be Open Source.

  • Hmm... I think I got your attention. :^) First of all, YES! Linux supports a serial console. Good. Thanks. I'm glad you got that out of your system. Now, the REAL problem is that your BIOS probably doesn't support a serial console.

    So what, you ask? Ah. Imagine that you have a box which you can't touch. You can't see it. You can only contact it through the net. What happens when it crashes? How do you turn it on or off? What happens if a device fails and it won't boot? You need the BIOS to send all messages over the serial console too. (Not to mention recieve things like reboot messages via that same console.)

    x86 BIOSs don't tend to support this feature. My company bought a 4 way Xeon from Micron ( []) and it had this ability in it's Pheonix BIOS. And Denarius Enterprises, Inc ( []) recently told me they will sell machines with this option as well. So others will probably sell you such machines -- you just have to ask.

  • Black Box [] makes several external power switch options that can be controlled by serial and/or touch tone. But they're not cheap.

    The other way to go might be to find a UPS that can cycle the power based on commands sent to its serial port. I know Best and some APCs can do this.
  • Hopefully the following (found via google) will help.

  • First thing, to be able to boot whithout a graphicsadapter you will need a PC with an Award BIOS. The Award BIOS has a seting _NO_VIDEO_INSTALLED_ .

    Second you will have to compile a 2.2 kernel with (or FreeBSD) with serialconsole option. To be able to login via your serialconsole you must also modify your inittab to run a getty on that console.

    Now comes the tricky parts. To be able to send an hard reset you will need special hardware, thats not good. An alternative solution would use some type of watchdog software. The basic function of a watchdog is to perform a softreset if the machine hangs (simplified that is).

    the next problem is what to do with all the serial cables? I hav no idea! Maybe there are some type of hub...

    Wonder when my grammar will improve?
  • i've set up a small farm of linux boxes for serving http, dns, and smtp/pop for employease []. i've been using the HP LPr machines: 2U form factor, twin cpu configuration. they have a serial/console out that you can configure linux to use. we are going to send all console interfaces to a cyclades [] console management system. i'm not sure the LPr's support remote power cycle signals via this interface, but I know the Dell Poweredge 6350's we're using do. unfortunately, these machines currently run NT since Netscape Enterprise server is not yet ported to linux. however, we have it from an insider that Enterprise server will be available in the fall. in the meantime, we are going to test out the quad-xeon-cpu 6350's as linux servers, and will find out if its console interface will actually work with linux.

    PS: Neither of these boxes care if they are headless, handless, or tailless.
  • You know, I love macs and all, but what the hell does Open Firmware have to do with remotely resetting and controlling Linux? OF will boot linuxppc on the mac, but you can't remotely start up or reboot the computer, and OF unloads itself when you start the OS anyways.
  • Of course, if the machine is too hosed to reboot, this obviously won't work. A hardware solution is required that turns the break signal into a hard reset.

    The software solution won't work any worse than Ctrl-Alt-Del (also handled in software). Also, sure, you can reboot from an interrupt context, in fact, it's often hard to *avoid* rebooting when you're in there :) (remember the good old triple fault?)
  • Yea, but how often has Linux crashed on you? .. like really gone dead.. not just an X problem that newbies whine about 'Linux crashing'.

    How 'ISPs do it' is just as this guy said (and I was going to mentiong too, seeing all this guff about serial switchboxes), by using ssh (or telnet if ya desperate)

    Okay for your *particular* purpose when you're hacking the kernel it might require a more 'thorough' solution, but IMHO for most people's uses (as I'm assuming this person's original request was, as he said about ISPs) is that ssh and telnet will work fine for controlling multiple machines.
  • I think it has to do with being a dedicated workstation or server. Even my Multa which was design to run NT still, gives me the message Keyboard not found sending all I/O to serial port 1.

    The problem is that PC hardware is designed for being a PC and not a headless server.

    But on the other hand even my 486 BIOS's allow for no keyboard/no video/no disk.
  • If you have a lot of computers that you need to do this with within the same organization, and are willing to accept a power off via a UPS in lieu of pressing the reset button, our company (Global Maintech) [] has a solution that will work over a LAN or WAN.

    It's actually designed to be a full management product that allows remote access to your consoles, along with the ability to run scripts that scan for stuff and automatically post alerts or do things in response to messages.

  • Note that there is also remote keyboard/mouse/video boxes that support very long cable lengths, and some that even bridge to a network, essentially acting as hardware remote control.

    Given that you can get a switcher pretty cheap nowdays, this might be a better solution than RS232.

  • Actualy, I thought Compaq and HP servers already had this special hardware built-in. Usually it's used over a network, but some Compaq server allow you to access "managablity" through RS232.
  • by David Huggins-Daines ( 12346 ) on Thursday June 17, 1999 @07:39AM (#1845761)
    Sounds like you want one of these []. They're not on the market yet, though, but they look super-cool.
  • The whole idea is to be able to have console access. You plain and simple cannot do this over telnet. If you are running 18 boxes like I am and are hacking networking drivers or other OS things, it is a pain to debug a crashed kernel or faulty hardware over the network when there is no networking stack (crashed kernel). You need true console access (SGIs and Sparcs do provide this). PCs don't (as of yet).

    KVMs are the only solution I have used reliably.
  • Black Box makes several external power switch options that can be controlled by serial and/or touch tone. But they're not cheap.

    The homebrew solution we had at the ISP I used to sysadmin for was all X-10 based. One password-capable phone responder with keypad for ~$85, and several of the lamp modules for under $10 each. Worked for power-cycling the terminal server and modem banks via phone or in person. [] is a good place to start.

  • When I was running an ISP I managed to get fairly close to the idea with PC hardware running NetBSD. NetBSD has had for a long time the ability for both the kernel and the bootloader to use a serial port for the console. I still had a switch box to get video and keyboard access to deal with the BIOS, but this wasn't that frequently needed, so I saved a lot of trips to the server room.

    We did have a couple of SPARCs running NetBSD as well, which of course Just Work when it comes to serial consoles.

    I understand that some Intel server motherboards have a BIOS that will also talk to the serial port. Given this, you'd be set.

    Another idea that a friend of mine was looking at was to build a little ISA card with a serial port on it that looked to the computer as if it was an MGA and keyboard. It would have to have logic to generate appropriate VT100 sequences to get the screen updated correctly for those things that assume the screen is fully addressable, but that shouldn't be a big deal. And, of course, it would have access to the reset line on the ISA bus (or it could plug into the reset button header on the motherboard itself). It would basically be a little console computer, much like the sort you used to have on minicomputers.

    Once you've got some sort of serial console working, I suggest using Paul Vixie's rtty [] program to monitor the machine. I bought a couple of eight-port BOCA serial boards and dropped them in an old 486 to make a console server.


  • The Linux kernel can handle serial consoles, but you'd probably have some issues with the BIOS. All Intel BIOSes that I've seen will go on strike if you try to boot without a keyboard.

    I suppose the next best thing to no monitor/keyboard would be one monitor/keyboard. Just get a KVM switch and some el-cheapo video cards for all your boxen.


  • The long-awaited NetWinder RM [] (the rackmount version of the NetWinder) is now shipping!
  • And they are even from my home town. Who knew Canuck's were so darn clever. :-)
  • I wish this subject had come up earlier. We recently threw away about 20 old dumb terminals of the Wyse flavor. For some reason our systems software supplier decided that instead of using a terminal to telnet to the host, we needed Windows and Visual Basic to do the same thing. We actually still have some terminals lying around though. Email me if you're interested.
  • I have four systems that I work with regularly in my office. I have a four banger Cybex switch box to control them. The basic idea is, you spend all that money for the egro keyboard, and 21" screen, you can use just one set of peripherals to control all the systems. There are monitor, mouse, and keyboard cables running from the back of each box to the Cybex. Then, the keyboard, monitor and mouse that I use run to a different set of ports on the Cybex, and BAM! There ya go, four systems, neatly running, with one set of periphs to control them.

    YMMV, of course, but I even use this solution with my home network. One more thing, you can set the Cybex to "scan." View one system for 5 seconds each, and switch to the next in line. They really are a neat trick, but a bit pricey.
  • It looked to me like there was aa ADB below the RS232, does that mean it could be eccessed from a Mac?

    "Trouble is, just because it's obvious doesn't mean it's true"

  • I didn't think that Linux supported DOC. I've got a videoless, keyboardless single board embedded system running off a DOC with ethernet, but it's running QNX.

    Has M-Systems added linux support?
  • My Psion 3a works great as a portable VT100 too. I am going to use it as the console for the box I'm putting in my car. No working TCP/IP support on the S3 series, but that's what the Linux host is for.

    I use the GPL'd "Nfsc" file-server and vt100-emulator ver 5.4. X/Y-modem don't work right in this version, but I can NFS mount the S3a's ramdisk and memory cards with a provided client!
  • Don't most PC BIOS's have the option for console redirect (I always wondered what to use it for). I think it will allow the proper OS to handle console work via COM1...
  • The point is that with a standard configuration with no keyboard and no video card does not allow
    you to re-configure the bios without plugging
    both the keyboard and a videocard in and attaching a monitor.

    The weasel seems to be an interesting work around.
    I wish them luck. :P
  • Yes,

    You can do a lot of hacking in software if that's what you like doing. If you need to get work done and can't spare the time get an Omniview Pro 8 port or 16 port ( or 4 port ) whatever you need.
    It is available out of the usual catalog places - Microwarehouse is one (

    I got an 8 port for ~400$, each set of cables costs about 12$. I am controlling a mixture of NT and Linux boxes, 6 of them under my desk, all from an onscreen control console. You can use the switch on the Omniview box to switch keyboard, mouse,monitor between machines. An LED display shows where you are in the sequence. In the onscreen display you can edit the defaults and enter your host names.
    You can daisy chain these to control some large multiple of 16 - 128 boxes or some such.

    To reboot just switch to the machine and give a three-finger salute, works like a charm. I haven't really found I need it all the time. Only to reboot. But it is *extremely* useful when you have to reboot. At other times I find am just using telnet and pseudo terminals.

    Good Luck.

    Nitin Borwankar
    ================================================ ========================================== =========
  • You can get a 2 or 4 system OmniCube KVM from Belkin for less than $100

    Yes, but don't forget to budget for better video cables, if you're going to be doing anything more than console work. Belkin's cable bundle includes a very low quality video cable whose signal, when combined with the switchbox, is not appropriate for high-resolution work. I've got an OmniCube 4-way, and bought some Belkin high-grade coax video cables. They're expensive (~$30 each), but make a noticable difference, at least at 1600x1200.

    Additionally, I'm not crazy about the Belkin's use of a double-tap of ScrollLock as the "trigger key" to get the attention of the unit, since ScrollLock actually causes action in some contexts (e.g., my FreeBSD console). A better key choice was made by Cybex with their SwitchView series, where a double-tap of Ctrl puts the unit into "command mode." That said, I'm still quite satisfied with the OmniCube (with enhanced cables, at least).

  • Most PCs have a setting in the advanced portion of the BIOS settings that disables the puase on error "feature" to allow the machine to continue booting through POST errors. This should get you through. Also a junk video card (old MCAs can be had if you'll just pick them up) might be useful.
  • Hi,

    I ran across a link in one of the user posts yesterday that led me to a web site that actually sells serial console cards for PCs.

    The setup is, this is an 8-bit ISA card that responds to the system like an MDA card. I'm guessing it intercepts writes into the text buffer of the MDA and outputs VT100 escape sequences or something. At least, that's what I'd do if I were them.

    Unfortunately, I don't have the URL handy, but I emailed the company (whose email is apparently different from the URL at which these cards reside, and I'm too friggin' lazy to go knocking about trying to root this out right now), and asked them to post in this thread so they may be roundly slashdotted.

    I'm going to pick up at least a couple of these things. Neat hack.

  • he next problem is what to do with all the serial cables? I hav no idea! Maybe there are some type of hub...

    Check around for IOLan terminal servers - up to 16 RS232 ports can be controlled from one, and they have an ethernet port - combined with a serial/ethernet accessible power switch of some kind (there are a few types available), that's perfect for sorting out network-dead servers from the comfort of my bedroom :-)
  • The point is to have a serial console, such that all kernel startup messages (and queries when fsck twitches and dies after an inoppertune reboot) go to the serial port. This is a Good Thing if you never intend to have a monitor or a keyboard connected (which is entirely possible with SCSI).

    The reason you don't want a getty running on /dev/ttyX in this situation is that /dev/ttyX doesn't exist. You've removed VGA support from the kernel, and leaving init to try to run all of those gettys will result in much spewage on one's (serial) console as they race to their death.

  • Most Award and Phoenix BIOSes allow you to set the halt on option to no errors, so that it will boot fine w/o a keyboard. Most systems will boot without a video card, our firewall here just beeps a lot and waits about 15 sec, but after that it carries on.

  • Yes, the excellent "feature" of being able to force a Sun box down to it's hardware prompt with a quick tap of the break key is really useful.

    That is, until someone power cycles a terminal server pugged into half your boxes. Opps, time to go and fix them all.. *grin*
  • Uh, well, sort of. You're not telnetting; you're attached to the box as the console. If the box is booted, you're "in Solaris." If the box is halted, you're in the ROM console.

    And since, on Sparcs, the output-to-Serial-A is handled by the ROM, it will work on S/Linux.
  • Why not put in an el cheapo useless video card?

    My server has a video card that hardly works in text mode but it keeps the machine happy to know it is there...
  • Yes they definitely do have support for linux; unfortunately (last I know) it was binary-only support.

    Use of DOC or IDE Flashdisks is often discussed on the LRP (Linux Router Project) mailing list. have a look at [].
  • i`ve got a IBM box (330-486DX4-100) at home that has the options in his bios to boot without a monitor and/or a keyboard and/or a floppy drive. just can`t remember what the bios is called.

  • by joe_90 ( 24661 ) on Thursday June 17, 1999 @09:09AM (#1845787) Homepage

    I think some people might be getting a touch confused here, so I'll try and restate the need.

    Basically with a Sun machine, you can attach a console to the back and watch the boot process, right from the point where the PROM detects no keyboard present and redirects the console to the serial line. It doesn't matter whether or not you have a video card present for the machine to boot.

    On a PC, depending on the BIOS you can or can't get away without a keyboard being present. However none (with the exception of the one I'm going to mention) will let you boot without a video card present. If the card is there then that is what will be your console.

    Now people were talking about using the SERIAL CONSOLE directive, or just running getty on the serial line, to redirect it and thats fine, provided the machine boots that far. With a Sun, if it fails to boot because of a problem with the hardware, or misconfiguration in the PROM (BIOS equivalent) you still have console access. On a PC you don't.

    Now Phoenix have just brought out a new BIOS which will let you redirect the console to a serial line in the same way as a Sun does, i.e. you can get to the BIOS from the serial line, edit parameters and force a powercycle. This is an immensely cool idea. In the ISP I worked in (one of the largest in Europe) we used vast amounts of PC based UNIX machines (OpenBSD, NetBSD and FreeBSD) none of which we could do this with.

    Check out verbios.html [] and scroll down to the bit about Serial Remote Console.



  • Don't some Ethernet Cards let you boot up remotely? this would solve a lot of problems I think... get an ATX case that can turn itself off through software, then boot of the ethernet... no need for serial cables ether :)
    Chad Okere
  • I remember booting Win98 on a Dell box. Got this little gem:
    DOS error: no keyboard detected.
    Press any key to continue.
  • I use a mouse to shutdown/reboot my headless/handless servers. Look at the man page for gpm and /etc/*gpm* for the configuration to execute a few commands with the proper mouse clicks.

    I find it useful to configure the mouse for shutdown and restart so an operator can have some control over the least to be able to cleanly shut the things off.

  • This whole switchbox thing touches lightly on a problem that I'm having... I've got an Omnicube 2way, and it switches the keyboard and video with no problem. The problem is the mouse... My linux box completely ignores it if it's run through the switch box. Plugging it in directly makes everything happy. I've swapped ports on the cube, just in case there was some badness there. The windows box plods along, the linux box ignores the mouse... Now, the other thing is that I have a logitech trackball, which is PS2.. the switchbox is PS2, the windows box is PS2.. the linux box is serial. Mayb it's a combo of the cube & the PS2 adaptor that causes the problem? Any help would be Grrrrreat!ly appreciated.

    Mail me... [mailto]
  • On our HP boxen at work we use the RemoteAssist cards to do this. The routers are configured to passthrough port connections to a serial port on the RA card allowing us to remotely take control of the boxes (from POST to GUI). GUI use requires PC/Anywhere and a compatible OS (Novell or NT I know, anyothers?)

    You can also view some management statistics and reboot or power off the box remotely using the RA card.
  • by ez8 ( 29763 )
    On my Linux PC Servers, my bios controls whether or not, it boots w/wo a keyboard. I have never changed any keyboard settings(on/off) with the OS. I do not a monitor attached to one, but it does have a cheap vga card in it. Just in case. This way I ensure one less reason for a reboot. Is there some kind of OS performance issue with removing the need for a keyboard/vga card?
    I do not know.

    Jar Jar and Obi-Wan are really good guys -- my 5yr old nephew
  • No, I'm pretty sure that is a ps/2 keyboard port. I think you connect a pass through from that to the keyboard port on the motherboard.
  • There are solutions like [] which allow you to control multiple devices (either 16 or 128) from a single console running serial cables out to all the headless machinery. They aren't the only ones out there. Also, I don't know that they would work on any Linux/xBSD or other free platforms. I do know they support Sun/Solaris and NT.

    BTW, I don't work for them. I am currently preparing to eval one of their products. They were very willing to send a demo of the hardware and software. Also, they aren't cheap but aren't outrageous.

  • I have a P133 with some sort of award BIOS, which boots without a video card without problems. It beeps three times when starting up and then continues with the boot process. of course you can't change the BIOS settings, but it's simply a case of getting them right before you take the gfx card out.
    Matthew Parslow
  • I run all my Linuxen (6 personal firewalls, 1 corporate web proxy, 1 corporate email server, 1 web-based-email server, 1 Intranet serer, 1 corporate webserver, 1 syslog server, 1 DHCP / NNTP server) keyboardless and monitorless. They all still have video cards of course. They all boot and run fine.

    I use AMI (what a horrible BIOS - I refuse to buy a board with the AMI WinBIOS on it), Award (my personal favorite) and Phoenix.

    Are you referring to Intel's own BIOS not working? Or just BIOS's on Intel platforms?
  • No kidding, I thought I had a haunting on my hands with all those ghosts... so I too exercised the demon back to the office, err, previous location :) Does anyone know of a vid switch that does it Right (shielded internally)?
  • You can possibly use a telnet application on a Palm Pilot to access the machine through the serial port. I've seen something similar done with the Pilot.
  • there are quite a few people in here who have it right when they mention that switching boxes et al cannot help you when you are 3000 miles away from the box that just crashed.

    a console server does just that....serves up consoles for multiple boxes over LAN's and WAN's.

    monitor and keyboard share boxes are fine when you have all of your boxes in the same room (and when you only have like 10 of them). but when you walk into our data center and see a hundreds of 6-foot-tall IBM and Sun boxes, you quickly realize that switch boxes are no longer an option.

  • yep - i have two ibm mail servers running linux with just two cords coming out the back...power and network. the ibm bios allows you to set it to keyboardless use, and i just run it w/o monitor and keyboard. however, since they are mail servers (and they ARE running linux) i never need to reboot them - these two have been up for six months or so. so, if for some reason you have need to reboot your headless box frequently, there might be some issues with that.
  • Try E-bay []: I've gotten a few good deals there and haven't been burned once.


  • It may be expensive, but this is the device you want. It allows remote telnet-to-serial control, plus power control (on/off/cycle), and you can also connect from any serial port to any other serial port... If your network's down, just dial up to the modem you connected. ;)

    There are a couple of companies that provide these products; Westeren Telematic [] and Baytech [].

    This works best if you are using it to manage several computers, because there is a minimum of 8 serial ports.

  • I tried to submit this URL to slashdot, but
    no one saw fit to post it: []

  • I haven't read the whole thread but here's a link to a fully configurable LCD terminal for linIx.

    LCDproc is a small program that extracts various statistics about your
    machine and displays them on an LCD display. It currently only
    supports 20x4 character displays, made by Matrix Orbital Corporation
    (a bunch of really cool people). Hit their web site at for pricing and ordering
    information. We'll be supporting more displays in future versions.

    Surgeon, ze nezherlandz
    (No prescription needed)

HELP!!!! I'm being held prisoner in /usr/games/lib!