Ken Yap - Markus Gutschke - Version 5.2.2
Copyright (C) 2001,2002,2003 Ken Yap and Markus Gutschke
2003-09-30
Revision History
This User Manual explains how to install, configure and compile the Etherboot package. The instructions here apply to version 5.2 of Etherboot.
This document and related documents are also kept online at the Etherboot Home Page. This will in general have the latest source distributions and documentation.
Comments on and corrections for this User Manual may be directed to the primary author.
This manual may be reproduced in whole or in part, without fee, subject to the following restrictions:
Thanks to Markus Gutschke who wrote the first version of this document, and to all the people who have contributed information and corrections to this document.
For a list of people who have contributed substantially to the code, please see the Acknowledgements section.
Etherboot is a software package for creating ROM images that can download code over an Ethernet network to be executed on a computer. Many network adapters have a socket where a ROM chip can be installed. Etherboot is code that can be put in such a ROM. Etherboot can also be booted from floppies (mainly for testing purposes but some people have been known to use this all the time) and hard disk, as a LILO/SYSLINUX compatible image, or from a hard disk partition, or via PXE.
Etherboot works on the x86, Itanium and Hammer architectures. It has not been ported to other platforms yet. Typically the computer is diskless and the code is Linux or FreeBSD, but these are not the only possibilities. The code uses the DHCP, tftp and NFS Internet Protocols, amongst others.
For a rather out of date but short talk/tutorial type introduction to what Etherboot does, see my SLUG talk.
Etherboot is Open Source under the GNU General Public License Version 2 (GPL2). The license conditions can be obtained from the file COPYING in the top directory of the distribution or viewed at www.gnu.org. In particular note that if you are distributing binaries generated from Etherboot, such as ROMs or ROM images, you must provide or promise to provide the user with the source. If you have not made private changes to the code, you can do this by pointing the user to the Etherboot home page, noting the release version of course. If you have made private changes to the code, then you must distribute those changes too with binary distributions.
The following is not legal advice and you should seek your own legal advice but it is a reasonable interpretation of the GPL with respect to Etherboot and BIOS code. Installing Etherboot, either as an extension BIOS or combined in the BIOS chip is mere aggregation. The GPL does not extend to other works that a GPLed binary is aggregated with on a storage medium. The rationale is this: The BIOS does not need an Etherboot ROM to function and the Etherboot ROM can work equally well with another BIOS implementation. Therefore putting Etherboot either on a ROM chip or in the same chip as the BIOS does not cause the two to become a combined work. Under this interpretation, there is no fear that you have to GPL your BIOS if you ship Etherboot with your BIOS.
The GPL applies to the whole package but a few files may be used under other licenses for historical reasons. See the Source copyrights section for details. Please support Open Source by joining the community and sharing. See the Etherboot home page (or Contributing) for some ways you can help Etherboot.
No Warranty or Support: Etherboot comes with NO warranties of any kind. It is hoped that it will be useful to you, but NO responsibility is accepted for any outcome of using it. Etherboot also comes with NO support, although you may get helpful advice from the mailing lists listed on the Etherboot home page.
See Appendix for a list of supported NICs. All Etherboot drivers are autoprobing, which means they attempt to detect the hardware addresses at which the card is installed. It's fairly easy to write a driver if you know C and are familiar with Ethernet hardware interfacing. Please read the developer manual if you wish to do so.
Please join the Etherboot mailing lists (Update AMH2006: Nowadays, only etherboot-discuss is an active discussion list). These are listed on the Etherboot home page. There is a users mailing list and a developers mailing list. The users list is for issues with building and running the software, while the developers list is for issues with features and coding.
Please post questions or bug reports to the Etherboot mailing lists, please do not mail me, because: 1. you get the benefit of a lot of experts seeing your question (no, I don't know everything, if only because there are many configurations I have never used); 2. a lot of people see the question and answer and this helps them too; 3. I have other demands on my time, like a job, and answering individual email is an unsustainable practice. You will probably not get any reply from me if you email me directly. I want to make the best use of my time and that is by making sure that as many people as possible see the questions and answers. Note that I will post my replies to the mailing lists so to see the answers you should subscribe, or be willing to check the archives later.
On the other hand, if you have a code or document contribution, then email to me is definitely appropriate. Please ask first before you send large files. Diffs are preferred to entire archives. If you are really keen to volunteer, and have the skills, ask to join the developer team.
Other lists you can join are the Linux Terminal Server Project mailing lists at LTSP. The LTSP list is focused more on the LTSP packages. However there is a fair amount of overlap between the lists and many key people are on all lists.
Marty Connor has set up a web form for creating an Etherboot image (Rom-o-Matic) on the fly and returning it as the output of the form. If all you want is an Etherboot image, this could save you having to build the distribution.
Unpack the distribution using gunzip and tar, using one of the following commands, where you replace x by the patchlevel number:
tar zxvf etherboot-5.2.x.tar.gz tar jxvf etherboot-5.2.x.tar.bz2 gunzip < etherboot-5.2.x.tar.gz | tar xvf - bunzip2 < etherboot-5.2.x.tar.bz2 | tar xvf -
If the documentation tarball was provided separately, then in addition do this:
cd etherboot-5.2.x
followed by one of the following:
tar zxvf ../etherboot-doc-5.2.x.tar.gz tar jxvf ../etherboot-doc-5.2.x.tar.bz2 gunzip < ../etherboot-doc-5.2.x.tar.gz | tar xvf - bunzip2 < ../etherboot-doc-5.2.x.tar.bz2 | tar xvf -
which will extract the documentation in a subdirectory of the Etherboot top directory.
To build an Etherboot image you need a recent release of gcc and the binutils tools. This package has been compiled with the tools from a SuSE 8.2 distribution but it should work with any recent Linux or FreeBSD distribution. gas 2.9.1 is too old to handle the 16-bit code in loader.S. Use gas 2.9.5 at least. Also the “gcc 2.96” used in RedHat 7.0 (and later versions maybe) generates faulty machine code compiling Etherboot. Use kgcc from those distributions instead.
Go to src/, edit the options in Config and make the image that you want. A full list of options is in Appendix B. We suggest you accept the default options for now if you are not sure what to select. Unlike 5.0, 5.2 does not make all the images by default, you have to explicitly state which ones you want.
You can test the image with a floppy before programming a ROM. On Linux just put a blank floppy in fd0 and say
make bin/card.zfd0
where card is the name of your network card and it will copy a bootable image onto the floppy. If you wish to do this by hand, perhaps because your floppy drive is elsewhere, just make bin/card.zdsk and copy this binary to the floppy raw, i.e. starting at the boot block.
cat bin/3c509.zdsk > /dev/fd0
You can also use utilities such as rawrite to write the image onto the floppy.
Make sure the floppy has no bad blocks. It is best if it has been formatted just before use. You do not need to put any kind of filesystem on it. If you wish, you could substitute /dev/fd0 with the actual device suitable for the floppy size you are using, for example /dev/fd0H1440 for 1.44 MB floppies. This may be more reliable than using the autodetecting device /dev/fd0.
When you boot with this floppy it will load the Etherboot image from floppy and execute it. If you chose the correct image, it should be able to detect your card. To get the bootrom to acquire an IP address and load the intended code, you need to set up DHCP, tftp and NFS services, which we will discuss in the next section. We suggest you continue to use floppy booting until you have completed the setup of the server and are satisfied that diskless booting works.
In addition, you can generate images with the suffixes .zlilo, .zpxe, .com, and .zrom by saying:
make bin/3c509.zlilo
and so forth.
The ones ending in .zlilo look sufficiently like Linux kernel images to be accepted by LILO, GRUB and SYSLINUX for installation. Unfortunately loadlin uses a slightly different method of booting for Linux kernels from LILO and SYSLINUX and will not work with these images.
The fact that .zlilo images look like a Linux kernel to LILO and SYSLINUX allows some interesting booting possibilities. For example, you could use LILO to select between DOS/Windows and Etherboot images from a disk that contains no Linux partitions, only FAT based partitions. This HOWTO shows you how this can be arranged.
The ones ending in .zpxe can be booted by a PXE booter. This is useful to chain to Etherboot from PXE. Here are some notes on how to combine PXE and Etherboot.
The ones ending in .com are DOS format executables, suitable for starting from DOS. It requires a real DOS environment, not a virtual DOS environment such as that provided by the DOS prompt window under Windows. Also it requires that there be no XMS drivers or other memory handlers loaded. It is not guaranteed to work if the environment is not clean, and sometimes not even if it is. The best chance of this format working is when DOS is booted with no device drivers whatsoever. If you can, use raw floppy or an intermediate bootloader for booting instead.
The ones ending in .zrom are images suitable for writing onto ROMs. If you are making a .zrom image, you must set the PCI vendor and device IDs correctly for PCI NICs. Look at the file NIC. Locate the line that has the correct PCI IDs for your NIC. This will give you the name of the ROM image you should use. The PCI IDs are usually displayed by the BIOS on booting up. They can also be read out from a running Linux system using the Linux PCI Utilities. If you do not use the ROM with the correct IDs, the floppy version will work, but the ROM will not since the BIOS will check for a match.
There are also .fd0, .dsk, .lilo, .pxe and .rom counterparts to the .z* versions of the images. The difference is the .z* versions are compressed. Unless you doubt the (de)compression process, there is usually no reason to use the uncompressed versions..
In this section I assume you want to boot a Linux kernel. Booting a FreeBSD kernel is documented elsewhere and does not require a generating a boot image. Booting a DOS kernel is similar, the main differences being in the way you set up the boot image.
Etherboot expects to download a boot image in either ELF or tagged format containing the code to be executed. Briefly explained, a boot image has a wrapper around the pieces of code or data that need to be put in various places in the computer's memory. It contains a directory telling how large the pieces are and where they go in memory. It also says where to start execution.
A boot image is created using a utility program. The utility program is specific to the kernel you want to load. The version for Linux is called mkelf-linux or mknbi-linux and that for DOS is mknbi-dos. These utilities are distributed separately and can be obtained from Etherboot web site.
The preferred method of running applications on the booted machine is to package an initial ramdisk (initrd) along with the kernel. This initrd can either provide all the files necessary for running the application (at a cost of using RAM to hold the files) or mount NFS filesystems to obtain other files. Therefore you will need to compile ramdisk options in your kernel. For an example of how an initrd is created and packaged, see the LTSP project sources.
After you have compiled the kernel, make the boot image, like this:
mkelf-linux --output=/tftpdir/xterm.nb zImage initrd.gz
This puts the image in where the tftp daemon expects to find it, in this example /tftpdir. Make sure it is world-readable because typically the tftp daemon runs as an unprivileged user. It is recommended that you set a path explicitly for tftpd instead of relying on any defaults. For example, for inetd, the entry in /etc/inetd.conf looks like this (xinetd uses a different syntax, check the documentation):
tftp dgram udp wait root /usr/sbin/tcpd in.tftpd /tftpdir
You need to set up a DHCP server to hand out an IP address and other configuration information to the client.
The main requirement of the DHCP server is that it needs to send out suitable configuration information. Prior to version 5.0.7, Etherboot accepted any DHCP offer (but see REQUIRE_VCI_ETHERBOOT below for an exception). Since version 5.0.7 Etherboot will not accept any DHCP offer where the server IP is empty (all zero) or the filename is empty. These offers are useless to Etherboot anyway so ignoring these offers will give it a better chance of picking the right DHCP server.
If you already have a DHCP server on your network for providing Windows clients with IP addresses, chances are that it is not a suitable DHCP server because it's only tailored to the single purpose of handing out client addresses. Suitable DHCP servers include the ISC DHCPD, available for most Unix/Linux systems. You can run such a DHCP server in parallel with the Windows one, provided you do not attempt to give Windows clients leases, in which case there would be a clash. You can exclude Windows clients in two ways. One is to register the only the MAC addresses of the diskless clients in /etc/dhcpd.conf, and to make sure that the server is declared “not authoritative”. The second is to look for the Vendor Class Identifier of “Etherboot-5.x” in the DHCP discover packet.
If you already have a DHCP server on your network that does provide the server IP and the filename, then you have to either use that DHCP server by editing its configuration file. This may require the cooperation of the system admin if you are not the admin. If you are not able to configure the DHCP server, then proceed to the section on REQUIRE_VCI_ETHERBOOT.
The minimum information you need to put in /etc/dhcpd.conf is:
next-server” parameter must be set to the TFTP server IP for recent ISC DHCPD (version 3.0.3? and newer) because default value changed to 0.0.0.0Here is a sample DHCP configuration for ISC dhcpd:
option domain-name "ken.net.au";
option domain-name-servers 192.168.0.1;
option broadcast-address 192.168.0.255;
use-host-decl-names on;
subnet 192.168.0.0 netmask 255.255.255.0 {
host xterm {
hardware ethernet 08:00:2B:B7:F3:80;
fixed-address xterm.ken.net.au;
filename "/tftpdir/xterm.nb";
}
}
The declaration “use-host-decl-names on” tells dhcpd to include the name xterm in the reply so that it can be used as part of pathname to mount by NFS, etc.
If your tftp server is not the same as the DHCP server, use the next-server declaration to specify a tftp server. (Update AMH2006: Always specify next-server for ISC DHCPD newer than 3.0.3)
The 2.4.4 and above kernels can do a separate DHCP request to obtain an address. Kernels in the 2.2 series use BOOTP. However user space DHCP configuration is now preferred.
More information about DHCP can be found at the DHCP FAQ.
If you are on a local network that is not directly connected to the Internet, you can use the “private” IP addresses 192.168.x.y (or in the other ranges mentioned in RFC1918, i.e. 10.x.y.z, 172.16.x.y - 172.31.x.y). Otherwise please ask either your network administrator or your Internet service provider for your own IP address(es).
You could use a bootp daemon instead of a DHCP daemon. However DHCP is preferred as DHCP provides more information to control the boot process. Also there is a bug in some old versions of bootpd where unnecessarily large reply packets are sent, causing packet fragmentation at the UDP level, and dropping of the packets by Etherboot. DHCPD can emulate bootpd if that's what you really want.
You may need to Etherboot in an environment where you have to install your own DHCP server, and it may interfere with the existing DHCP server. Etherboot has a feature designed to overcome this problem. It consists of two parts:
The first part is Etherboot contains code that when it sends out a DHCPDISCOVER request, a tag containing a Vendor Class Identifier of “Etherboot-x.y” is sent out, where x.y is the version number, currently 5.2. The 5 and the 2 are printable digits, not binary values, i.e. byte values 53 and 50 respectively. This allows the server to identify Etherboot clients and ignore all others.
The second part is Etherboot can be conditionally compiled to require a Vendor Encapsulated Option containing a VCI of “Etherboot”, otherwise it will ignore the DHCPOFFER. The option is not compiled in by default because it would cause Etherboot to not boot in plain setups. The server we want to respond will include this tag in DHCPOFFERs and while other servers (e.g. Windows servers) may respond, they will be ignored.
Vendor Encapsulated Option is supported in ISC DHCPD 2 or 3. (It's not documented in DHCPD 2, but it works.) Other DHCP servers may support VEO. (It's a RFC2132 option.) In ISC DHCPD 3, follow the documentation for declaring a VEO scope. In ISC DHCPD 2 the magic line required is:
option vendor-encapsulated-options 3c:09:45:74:68:65:72:62:6f:6f:74:ff;
Put this in the appropriate scope. Translation: Vendor Encapsulation Options (Option 43) encloses: Vendor Class Identifier (Option 60 = 0x3c), length 9, value “Etherboot”; End of Options (Option 255 = 0xff). If you have a DHCP server already running for the subnet, you probably should specify that your additional ISC DHCPD server is not authoritative for the the subnet, or it will veto (NAK) existing client IP address allocations, upsetting the status quo. See the ISC DHCPD options documentation.
Here is a practical document (AMH2006: Dead link, sorry) describing how it is done.
Now set up a tftp daemon. This means installing the tftp package and making sure that the tftp service is active in /etc/inetd.conf. If you want to be very careful you may wish to use the secure (-s) option of tftpd, this chroots to the specified directory, but then your pathnames in /etc/dhcpd.conf must be relative to the new root directory.
If you are booting many clients you should be aware of the limitations of running tftpd from inetd. Typically inetd has limits on how often a daemon can be spawned, to detect runaway daemons. If many clients request the tftp service within a short period, inetd may shutdown that service. If you have a setup where there are many clients, it may be better to use an improved replacement for inetd, such as xinetd. Another possibility is to install a better tftp daemon like atftp at the Etherboot web site. This one can be run as a standalone daemon, avoiding *inetd limitations and it multithreads internally.
Now when you start up Etherboot, it should obtain an IP address and print out what it received. If you do not get this to work, turn on debugging in DHCPD and see if any query was received. You may also wish to use the tcpdump or ethereal utilities to watch the network for DHCP packets (port bootps). If not, check your network hardware (cables, etc). If a query was received, check if DHCPD was able to give an answer. If not, then the Ethernet address was not found in /etc/dhcpd.conf. If a reply was sent, then only faulty hardware or a bug in Etherboot would prevent it being received by Etherboot.
Assuming an IP address was received, the next thing Etherboot tries to do is load a file using tftp. Check your system logs to see if a tftp daemon was started up and a file requested. Generally if you run tftpd under tcpwrapper security, a log entry will be generated. If not, it could be a path problem or file permission problem (the file needs to be readable by tftpd). Another problem could be that tftpd needs to reverse map the IP address to a name for security checking, and you don't have the client's details in /etc/hosts or in DNS, or your tcpwrapper config files (/etc/hosts.deny, /etc/hosts/allow) do not allow the access. Fix the problem.
After the boot image is loaded, Etherboot will jump to it. If it crashes here, check that the image is a boot image. If it executes and stops at the point where it's trying to mount NFS filesystems, then you need to check your NFS mounts. Another common problem is the shared libraries on the NFS partition are not suitable for your CPU, e.g. i586 libraries but a 486 diskless client.
Recent advances in the Linux kernel (2.4 and above) have made the use of an initrd that does user space autoconfiguration and mounting of a NFS root filesystem, followed by a pivot_root, a more flexible alternative to kernel autoconfiguration and mounting of a NFS root filesystem. Postings on the kernel mailing lists indicate that at some point in the future, kernel level autoconfiguration (BOOTP/DHCP from the kernel) may be removed from the Linux kernel and initrds will be the recommended way to start up a diskless system.
Until I have time to write detailed instructions on how to construct the initrd, I refer you to the LTSP distribution which uses this technique. Mknbi supports initrds, see the ramdisk argument of ''mkelf-linux''. The Linux kernel documentation describes the extra arguments should be passed to the kernel to make it use an initrd, and how to arrange the initrd so that the startup script within it is called when it's mounted. If the initrd mounts a NFS root filesystem then it should still have all the needed structure as explained in the next section.
Initrds can also be used for mounting other network filesystems instead of NFS root. Some applications could even run totally out of initrd, e.g. Floppy Firewall, provided you have the memory, of course.
This tutorial does not cover all possible ways of setting up a diskless client's initial filesystem. You could even mount a conventional hard disk. Why would you want to boot “diskless” if you have a hard disk? Reasons might be: you do not wish to administer the local disk; you want the assurance that a system is running a kernel from a central server; or you like the speed of network booting. Network booting is one technique in a toolbox. Techniques can be combined to do what you want. If you are interested in running the diskless client as an X-terminal, a very common use, you may wish to investigate the Linux Terminal Server Project.
Swap over NFS can be arranged but you have to patch the kernel source. See here.
Be aware that opinions are divided on NFS swap. Some people think it's a bad thing because it just kills the network if you have lots of diskless computers and that you shouldn't be running into a swap regime on a diskless computer anyway. Some other people like having a bit of insurance.
Also have a look at the NBD Network Block Device for swapping over that.
There is also the follow-on project ENBD, the Enhanced Network Block Driver. I have no experience with this for swapping. Comments welcome.
What about DOS? The deal with DOS is that one is loading a virtual floppy called A: into extended memory and then booting from this floppy. So you have to capture an image of a bootable DOS floppy first. Some more details can be found in the ''mknbi-dos'' utility.
I have booted DOS (both M$ versions up to 5.0 and DR versions up to 7.03) diskless this way. A ''mknbi-fdos'' is available for building boot images for booting FreeDOS, the procedure differs slightly from booting M$ or DR DOS.
If you were thinking of booting a Windows machine via the network, it seems (I'm not masochistic enough to do this) the problem is not the network booting but the mounting of a file system over NetBIOS (Windows does not do remote mounts of root filesystems over NetBIOS on TCP). So that rules out a Samba server. It appears to be possible over a Netware server, for which Linux or FreeBSD has workalikes. Also it is said that only certain versions of Windows will allow diskless booting. You will also have problems with pathnames and the usual Windows hassles. Do you really want to do this? You do know that you can run lots of desktop applications like Netscape, StarOffice, etc. on Linux, FreeBSD, etc. now? Why pay good money when you can use equally good free replacements? Anyway if you are still determined, in the Etherboot home page, there are links to external Web pages, one explaining how this was done with a commercial TCP/IP boot ROM, another explaining how to do it using Etherboot and Netbios over IPX. A recent user experience is (AMH2006: Dead link, sorry) here. Good luck and send us your experiences or better still a URL to a page explaining how you did it.
Assuming you have satisfactorily set up your server environment, you may now wish to put the Etherboot onto an EPROM or EEPROM. Naturally this assumes access to hardware to program (and possibly erase) EPROMs. Access to a friendly electronics engineer and/or lab is one way to program and erase EPROMs. Otherwise you can look at the commercial links page for places you can buy programmed EPROMs from.
Some high-end network cards, for example the 3Com 905B, have a socket for an EEPROM which can be programmed in situ with the right utilities. See any release notes accompanying Etherboot for more information.
Most network cards come with a blank (E)EPROM socket even though it is seldom used. When it is used, it is typically filled with a proprietary EPROM from the network card manufacturer. You can put an Etherboot EPROM there instead.
First you must discover how to enable the EPROM socket on your card. Typically the EPROM is not enabled from the factory and a jumper or a software configuration program is used to enable it.
Secondly, you must discover what size and speed of EPROM is needed. This can be difficult as network card manufacturers often neglect to provide this information.
The smallest EPROM that is accepted by network cards is an 8k EPROM (2764). 16kB (27128), 32kB (27256), 64kB (27512) or even 128kB (27010) EPROMs are possible. (You will often see a C after the 27, e.g. 27C256. This indicates a CMOS EPROM, which is equivalent to the non-C version and is a good thing because of lower power consumption.) You want to use the smallest EPROM you can so that you don't take up more of the upper memory area than needed as other extensions BIOSes may need the space. However you also want to get a good price for the EPROM. Currently the 32kB and 64kB EPROMs (27256 and 27512) seem to be the cheapest per unit. Smaller EPROMs appear to be more expensive because they are out of mainstream production.
If you cannot find out from the documentation what capacity of EPROM your card takes, for ISA NICs only, you could do it by trial and error. (PCI NICs do not enable the EPROM until the BIOS tells the NIC to.) Take a ROM with some data on it (say a character generator ROM) and plug it into the socket. Be careful not to use an extension BIOS for this test because it may be detected and activated and prevent you from booting your computer. Using the debug program under DOS, dump various regions of the memory space. Say you discover that you can see the data in a memory window from CC00:0 to CC00:3FFF (= 4000 hex = 16384 decimal locations). This indicates that a 16kB EPROM is needed. However if you see an alias in parts of the memory space, say the region from CC00:0 to CC00:1FFF is duplicated in CC00:2000 to CC00:3FFF, then you have put an 8kB EPROM into a 16kB slot and you need to try a larger EPROM.
Note that because pinouts for 28 pin EPROMs are upward compatible after a fashion, you can probably use a larger capacity EPROM in a slot intended for a smaller one. The higher address lines will probably be held high so you will need to program the image in the upper half or upper quarter of the larger EPROM, as the case may be. However you should double check the voltages on the pins armed with data sheet and a meter because CMOS EPROMs don't like floating pins.
If the ROM is larger than the size of the image, for example, a 32 kB ROM containing a 16 kB image, then you can put the image in either half of the ROM. You will sometimes see advice to put two copies of the image in the ROM. This will work but is not recommended because the ROM will be activated twice if it's a legacy ROM and may not work at all if it's a PCI/PnP ROM. It is tolerated by Etherboot because the code checks to see if it's been activated already and the second activation will do nothing. The recommended method is to fill the unused half with blank data. All ones data is recommended because it is the natural state of the EPROM and involves less work for the PROM programmer. Here is a Unix command line that will generate 16384 bytes of 0xFF and combine it with a 16 kB ROM into a 32 kB image for your PROM programmer.
(perl -e 'print "\xFF" x 16384'; cat bin/3c509.zrom) > 32kbimage
The speed of the EPROM needed depends on how it is connected to the computer bus. If the EPROM is directly connected to the computer bus, as in the case of many cheap NE2000 clones, then you will probably have to get an EPROM that is at least as fast as the ROMs used for the main BIOS. This is typically 120-150 ns. Some network cards mediate access to the EPROM via circuitry and this may insert wait states so that slower EPROMs can be used. Incidentally the slowness of the EPROM doesn't affect Etherboot execution speed much because Etherboot copies itself to RAM before executing.
If you have your own EPROM programming hardware, there is a nice collection of EPROM file format conversion utilities here. The files produced by the Etherboot build process are plain binary. A simple binary to Intel hex format converter can be found in this wiki here.
Etherboot is believed to make PnP compliant ROMs for PCI NICs. A long-standing bug in the headers has been tracked down. However some faulty old BIOSes are out there so I have written a Perl script swapdevids.pl to switch the header around if necessary. You'll have to experiment with it both ways to find out which works. Or you could dump a ROM image that works (e.g. RPL, PXE ROM) using the Perl script disrom.pl. The fields to look at are Device (base, sub, interface) Type. It should be 02 00 00, but some BIOSes want 00 00 02 due to ambiguity in the original specification.
/dev directory is missing entries for /dev/zero and/or /dev/null or is sharing device entries from a server that uses different major and minor numbers (i.e. a server that is not running Linux). /lib directory is missing libraries (most notably libc* and/or libm*) or does not have the loader files ld*.so* /etc/inittab and/or /etc/rc.d/* files have not been customised for the clients. For example if you set the wrong IP address in your client's init files you could interfere with the server. init executable (in one of the directories known by the kernel: /etc, /sbin, ?). Remember /sbin/init must be a real file, not a symlink. /etc/inittab/dev/tty? /bin/sh/var (mount and /etc/mtab* is the canonical example) Please check this section if you have a problem before asking on the mailing lists.
cat bin/boot1a.bin bin/foo.rom > /dev/fd0, or make bin/foo.fd0) but the loader prints out an error. X -query server runs but all I get is a gray stippled screen. mknbi utility supports creating boot images from FreeDOS kernels now. See the man page for details. FreeDOS is under development and if the layout of the kernel image changes, please send any corrections to me. rmrd.com program supplied with ''mknbi''. –harddisk option of mknbi-dos is intended for this. It causes your boot drive to be C:, so you can use A: for the real floppy. See the man page for more details (AMH2006:) Information about flashing EtherBoot into your BIOS is also available on a separate wiki page.
Here is some text contributed by Dirk von Suchodoletz. He hopes to put it on a web site someday:
6.4 Using your mainboard's BIOS to integrate etherboot-code Newer mainboards that have an AWARD-BIOS can use etherboot without separate EPROMS and therefore without the necessity of having a EPROM-programmer[?]. (Heinrich Rebehn wishes to add: Flashing the BIOS is always a (small) risk. Flashing with unsupported, hacked BIOS image is *dangerous* and may render your PC unbootable. If you don't have access to a PROM burner you should stay away from experimenting.) In order to do this, you need 2 software tools: awdflash.exe, which should be included in your mainboard package, and cbrom.exe, which is an OEM-tool that allows modifications of the BIOS. awdflash.exe reads and writes the flashrom content, whereas cbrom.exe is used to analyse the content of the AWARD BIOS image. cbrom.exe can also add code to the BIOS image or remove components. This way you can easily integrate etherboot into your mainboards without even opening the PC's case. After the BIOS image has been saved (e.g. as bios.bin), or in case the current version of the BIOS has been copied from the board manufacturer's website, 'cbrom bios.bin /d' shows how much space is left on the image for your code. As the flashrom holds the compressed BIOS, cbrom will also compress the code when adding it to the BIOS. Therefore, 8 to 20 kbyte of free memory is needed, depending on the network adapter's driver. In case not enough memory is left, unneeded BIOS components can be removed from the BIOS image to regain space: the manufacturer's logo or the Symbios/NCR SCSI-code are note needed for diskless systems. 'cbrom bios.bin /[pci|ncr|logo|isa] release' will remove those unnecessary components. The command line "cbrom bios.bin /[pci|isa] bootimg.rom [D000:0]" adds the compiled etherboot code to the bios. bootimg.rom is the code we would use to burn onto EEPROMs in other cases. Depending on your network card, either the pci or isa options have to be used. With isa cards you have to tell cbrom to which RAM location the code will be extracted at boot time. Attention: Compile the etherboot with the -DASK_BOOT or -DEMERGENCYDISKBOOT option to be able to access a disk. The code added by cbrom will be executed before the computer seeks for a boot disk or floppy. 6.5 Booting with a DOS executable (COM) file If the computer has to be used with more than one operating systems, for example using the computer as an X-Terminal in addition to the already installed NT on the harddrive, etherboot has to be used with the compile-time option -DASK_BOOT. In case hardware-conflicts between Windows NT and the installed EPROM exist, creating DOS Executables (e.g. using 'make rtl8139.com') can provide a useful remedy. Those DOS Executables are comparable in their functionality to .rom images and can be used as substitutes. In case an existing DOS-bootsector, stored in BOOTSECT.DOS, cannot be used, creating one has to be done by formatting and installing a harddrive using DOS before installing NT (see Win-NT Multiboot-HOWTO). In addition the DOS system files are needed (IO.SYS, MSDOS.SYS, or KERNEL.SYS when using FreeDOS) and have to be copied into the directory of the NT loader. If using Autoexec.bat to start the .COM file is desired, either the particular COMMAND.COM has to be provided or the etherboot file needs to be renamed as COMMAND.COM. This file will then be started instead of the DOS-Shell which is useful for avoiding unwanted user interaction. Afterwards a line has to be added to BOOT.INI as if DOS was to be booted: [boot loader] timeout=20 default=C:\bootsect.dos #add this line if dhcp/tftp should be default action [operating systems] multi(0)disk(0)rdisk(0)partition(2)\WINNT="Windows NT Workstation, Version 4.0" [VGA-Modus]" /basevideo /sos C:\bootsect.dos="DHCP/TFTP (Linux diskless via etherboot)" #our boot option
And here are some comments by Rapp Informatik Systeme GmbH about cbrom.exe versions:
Some more remarks for cbrom.. There are several version numbers of cbrom.exe p.e. 1.x and 2.x. and there is a cbrom called cbrom6.exe. First cbrom.exe with Version 1.x (newest 1.32) is for Award Bios Version 4.5x and cbrom6.exe is for Award Bios Version 6.xx. So because it seems a lot people become confused and use cbrom 1.x for the new 6.x Bios Award merged this together to a cbrom.exe with Version number 2.x ( newest know 2.04) witch now runs on Award 4.5x and 6.xx Bioses. Now how to find cbrom.exe. Different 1.x Versions of cbrom.exe could be found on the net, cbrom6.exe seems to be gone. It seems that Award/Phoenix do all that cbrom is deleted from servers of board manufactures. So cbrom.exe Vers 2.04 is not available on the net. If somebody need this please try to send a demand question to the list - I hope somebody will mail it to you.
The following people have contributed substantially to Etherboot. If you feel your name has been left out, just let me know and I will fix it up.
The boot code from FreeBSD is under the BSD license. The code taken from the Linux PCI subsystem and Linux NIC drivers are under GPL. Some source files have been put under GPL by their authors. Hence the Etherboot distribution is in general under the GPL, but you may use parts of it derived from FreeBSD under FreeBSD rules. Simply speaking, the GPL says that if you distribute a binary derived from Etherboot code (this includes boot ROMs) you have to provide, or promise to provide on demand, the source code. The full conditions of the GPL are specified in the file COPYING.
Here are the copyright details of the source, file by file:
Unless specifically noted, a file is under the GPL. GPLed files are in general either from Linux or have been explicitly put under GPL by the authors. A few files are inherited from FreeBSD netboot and therefore can be used under BSD or GPL.
File Copyright status core/misc.c BSD drivers/net/3c509.c BSD drivers/net/3c509.h BSD drivers/net/3c595.c BSD drivers/net/3c595.h BSD drivers/net/3c90x.c Open Source drivers/net/epic100.c None drivers/net/epic100.h None drivers/net/ns8390.c BSD drivers/net/ns8390.h BSD drivers/net/tulip.c BSD arch/i386/include/bits/string.h None util/lzhuf.c Open Source
The following is the current NIC configuration file as of 2003-09-23. .
# This is an automatically generated file, do not edit # It does not affect anything in the build, it's only for rom-o-matic family drivers/net/skel skel-pci 0x0000,0x0000 Skeleton PCI Adaptor skel-isa - Skeleton ISA driver family drivers/net/3c595 3c590 0x10b7,0x5900 3Com590 3c595 0x10b7,0x5950 3Com595 3c595-1 0x10b7,0x5951 3Com595 3c595-2 0x10b7,0x5952 3Com595 3c900-tpo 0x10b7,0x9000 3Com900-TPO 3c900-t4 0x10b7,0x9001 3Com900-Combo 3c900b-tpo 0x10b7,0x9004 3Com900B-TPO 3c900b-combo 0x10b7,0x9005 3Com900B-Combo 3c900b-tpb2 0x10b7,0x9006 3Com900B-2/T 3c900b-fl 0x10b7,0x900a 3Com900B-FL 3c980-cyclone-1 0x10b7,0x9800 3Com980-Cyclone 3c9805-1 0x10b7,0x9805 3Com9805 3csoho100-tx-1 0x10b7,0x7646 3CSOHO100-TX 3c450-1 0x10b7,0x4500 3Com450 HomePNA Tornado family drivers/net/3c90x 3c905-tpo 0x10b7,0x9000 3Com900-TPO 3c905-t4 0x10b7,0x9001 3Com900-Combo 3c905-tpo100 0x10b7,0x9050 3Com905-TX 3c905-combo 0x10b7,0x9051 3Com905-T4 3c905b-tpo 0x10b7,0x9004 3Com900B-TPO 3c905b-combo 0x10b7,0x9005 3Com900B-Combo 3c905b-tpb2 0x10b7,0x9006 3Com900B-2/T 3c905b-fl 0x10b7,0x900a 3Com900B-FL 3c905b-tpo100 0x10b7,0x9055 3Com905B-TX 3c905b-t4 0x10b7,0x9056 3Com905B-T4 3c905b-9058 0x10b7,0x9058 3Com905B-9058 3c905b-fx 0x10b7,0x905a 3Com905B-FL 3c905c-tpo 0x10b7,0x9200 3Com905C-TXM 3c980 0x10b7,0x9800 3Com980-Cyclone 3c9805 0x10b7,0x9805 3Com9805 3csoho100-tx 0x10b7,0x7646 3CSOHO100-TX 3c450 0x10b7,0x4500 3Com450 HomePNA Tornado family drivers/net/eepro100 id1029 0x8086,0x1029 Intel EtherExpressPro100 ID1029 id1030 0x8086,0x1030 Intel EtherExpressPro100 ID1030 82801cam 0x8086,0x1031 Intel 82801CAM (ICH3) Chipset Ethernet Controller eepro100-1032 0x8086,0x1032 Intel PRO/100 VE Network Connection eepro100-1033 0x8086,0x1033 Intel PRO/100 VM Network Connection eepro100-1034 0x8086,0x1034 Intel PRO/100 VM Network Connection eepro100-1035 0x8086,0x1035 Intel 82801CAM (ICH3) Chipset Ethernet Controller eepro100-1036 0x8086,0x1036 Intel 82801CAM (ICH3) Chipset Ethernet Controller eepro100-1037 0x8086,0x1037 Intel 82801CAM (ICH3) Chipset Ethernet Controller id1038 0x8086,0x1038 Intel PRO/100 VM Network Connection 82562et 0x8086,0x1039 Intel PRO100 VE 82562ET id103a 0x8086,0x103a Intel Corporation 82559 InBusiness 10/100 82562etb 0x8086,0x103b Intel PRO100 VE 82562ETB eepro100-103c 0x8086,0x103c Intel PRO/100 VM Network Connection eepro100-103d 0x8086,0x103d Intel PRO/100 VE Network Connection eepro100-103e 0x8086,0x103e Intel PRO/100 VM Network Connection 82551qm 0x8086,0x1059 Intel PRO/100 M Mobile Connection 82559er 0x8086,0x1209 Intel EtherExpressPro100 82559ER 82865 0x8086,0x1227 Intel 82865 EtherExpress PRO/100A 82556 0x8086,0x1228 Intel 82556 EtherExpress PRO/100 Smart eepro100 0x8086,0x1229 Intel EtherExpressPro100 82562em 0x8086,0x2449 Intel EtherExpressPro100 82562EM 82562-1 0x8086,0x2459 Intel 82562 based Fast Ethernet Connection 82562-2 0x8086,0x245d Intel 82562 based Fast Ethernet Connection 82562ez 0x8086,0x1050 Intel 82562EZ Network Connection eepro100-5200 0x8086,0x5200 Intel EtherExpress PRO/100 Intelligent Server eepro100-5201 0x8086,0x5201 Intel EtherExpress PRO/100 Intelligent Server family drivers/net/e1000 e1000-82542 0x8086,0x1000 Intel EtherExpressPro1000 e1000-82543gc-fiber 0x8086,0x1001 Intel EtherExpressPro1000 82543GC Fiber e1000-82543gc-copper 0x8086,0x1004 Intel EtherExpressPro1000 82543GC Copper e1000-82544ei-copper 0x8086,0x1008 Intel EtherExpressPro1000 82544EI Copper e1000-82544ei-fiber 0x8086,0x1009 Intel EtherExpressPro1000 82544EI Fiber e1000-82544gc-copper 0x8086,0x100c Intel EtherExpressPro1000 82544GC Copper e1000-82544gc-lom 0x8086,0x100d Intel EtherExpressPro1000 82544GC LOM e1000-82540em 0x8086,0x100e Intel EtherExpressPro1000 82540EM e1000-82545em-copper 0x8086,0x100f Intel EtherExpressPro1000 82545EM Copper e1000-82546eb-copper 0x8086,0x1010 Intel EtherExpressPro1000 82546EB Copper e1000-82545em-fiber 0x8086,0x1011 Intel EtherExpressPro1000 82545EM Fiber e1000-82546eb-fiber 0x8086,0x1012 Intel EtherExpressPro1000 82546EB Copper e1000-82541ei 0x8086,0x1013 Intel EtherExpressPro1000 82541EI e1000-82540em-lom 0x8086,0x1015 Intel EtherExpressPro1000 82540EM LOM e1000-82540ep-lom 0x8086,0x1016 Intel EtherExpressPro1000 82540EP LOM e1000-82540ep 0x8086,0x1017 Intel EtherExpressPro1000 82540EP e1000-82541ep 0x8086,0x1018 Intel EtherExpressPro1000 82541EP e1000-82547ei 0x8086,0x1019 Intel EtherExpressPro1000 82547EI e1000-82546eb-quad-copper 0x8086,0x101d Intel EtherExpressPro1000 82546EB Quad Copper e1000-82540ep-lp 0x8086,0x101e Intel EtherExpressPro1000 82540EP LP family drivers/net/tg3 tg3-5700 0x14e4,0x1644 Broadcom Tigon 3 5700 tg3-5701 0x14e4,0x1645 Broadcom Tigon 3 5701 tg3-5702 0x14e4,0x1646 Broadcom Tigon 3 5702 tg3-5703 0x14e4,0x1647 Broadcom Tigon 3 5703 tg3-5704 0x14e4,0x1648 Broadcom Tigon 3 5704 tg3-5702FE 0x14e4,0x164d Broadcom Tigon 3 5702FE tg3-5705 0x14e4,0x1653 Broadcom Tigon 3 5705 tg3-5705_2 0x14e4,0x1654 Broadcom Tigon 3 5705_2 tg3-5705M 0x14e4,0x165d Broadcom Tigon 3 5705M tg3-5705M_2 0x14e4,0x165e Broadcom Tigon 3 5705M_2 tg3-5782 0x14e4,0x1696 Broadcom Tigon 3 5782 tg3-5788 0x14e4,0x169c Broadcom Tigon 3 5788 tg3-5702X 0x14e4,0x16a6 Broadcom Tigon 3 5702X tg3-5703X 0x14e4,0x16a7 Broadcom Tigon 3 5703X tg3-5704S 0x14e4,0x16a8 Broadcom Tigon 3 5704S tg3-5702A3 0x14e4,0x16c6 Broadcom Tigon 3 5702A3 tg3-5703A3 0x14e4,0x16c7 Broadcom Tigon 3 5703A3 tg3-5901 0x14e4,0x170d Broadcom Tigon 3 5901 tg3-5901_2 0x14e4,0x170e Broadcom Tigon 3 5901_2 tg3-9DXX 0x1148,0x4400 Sysconnet 9DXX tg3-9MXX 0x1148,0x4500 Sysconnet 9MXX tg3-ac1000 0x173b,0x03e8 Altima AC1000 tg3-ac1001 0x173b,0x03e9 Altima AC1001 tg3-ac9100 0x173b,0x03ea Altima AC9100 tg3-ac1003 0x173b,0x03eb Altima AC1003 family drivers/net/pcnet32 lancepci 0x1022,0x2000 AMD Lance/PCI pcnetfastiii 0x1022,0x2625 AMD Lance/PCI PCNet/32 amdhomepna 0x1022,0x2001 AMD Lance/HomePNA family drivers/net/tulip dc21040 0x1011,0x0002 Digital Tulip ds21140 0x1011,0x0009 Digital Tulip Fast dc21041 0x1011,0x0014 Digital Tulip+ ds21142 0x1011,0x0019 Digital Tulip 21142 mx98713 0x10d9,0x0512 Macronix MX987x3 mx98715 0x10d9,0x0531 Macronix MX987x5 mxic-98715 0x1113,0x1217 Macronix MX987x5 lc82c115 0x11ad,0xc115 LinkSys LNE100TX 82c168 0x11ad,0x0002 Netgear FA310TX dm9100 0x1282,0x9100 Davicom 9100 dm9102 0x1282,0x9102 Davicom 9102 dm9009 0x1282,0x9009 Davicom 9009 centaur-p 0x1317,0x0985 ADMtek Centaur-P an981 0x1317,0x0981 ADMtek AN981 Comet an983 0x1113,0x1216 ADMTek AN983 Comet an983b 0x1317,0x9511 ADMTek Comet 983b centaur-c 0x1317,0x1985 ADMTek Centaur-C intel21145 0x8086,0x0039 Intel Tulip ax88140 0x125b,0x1400 ASIX AX88140 rl100tx 0x11f6,0x9881 Compex RL100-TX xircomtulip 0x115d,0x0003 Xircom Tulip tulip-0981 0x104a,0x0981 Tulip 0x104a 0x0981 tulip-2774 0x104a,0x2774 Tulip 0x104a 0x2774 tulip-9511 0x1113,0x9511 Tulip 0x1113 0x9511 tulip-1561 0x1186,0x1561 Tulip 0x1186 0x1561 tulip-a120 0x1259,0xa120 Tulip 0x1259 0xa120 tulip-ab02 0x13d1,0xab02 Tulip 0x13d1 0xab02 tulip-ab03 0x13d1,0xab03 Tulip 0x13d1 0xab03 tulip-ab08 0x13d1,0xab08 Tulip 0x13d1 0xab08 lanfinity 0x14f1,0x1803 Conexant LANfinity tulip-8410 0x1626,0x8410 Tulip 0x1626 0x8410 tulip-ab09 0x1737,0xab09 Tulip 0x1737 0xab09 family drivers/net/davicom davicom9100 0x1282,0x9100 Davicom 9100 davicom9102 0x1282,0x9102 Davicom 9102 davicom9009 0x1282,0x9009 Davicom 9009 davicom9132 0x1282,0x9132 Davicom 9132 family drivers/net/rtl8139 rtl8129 0x10ec,0x8129 Realtek 8129 rtl8139 0x10ec,0x8139 Realtek 8139 rtl8139b 0x10ec,0x8138 Realtek 8139B dfe538 0x1186,0x1300 DFE530TX+/DFE538TX smc1211-1 0x1113,0x1211 SMC EZ10/100 smc1211 0x1112,0x1211 SMC EZ10/100 delta8139 0x1500,0x1360 Delta Electronics 8139 addtron8139 0x4033,0x1360 Addtron Technology 8139 dfe690txd 0x1186,0x1340 D-Link DFE690TXD fe2000vx 0x13d1,0xab06 AboCom FE2000VX allied8139 0x1259,0xa117 Allied Telesyn 8139 fnw3603tx 0x14ea,0xab06 Planex FNW-3603-TX fnw3800tx 0x14ea,0xab07 Planex FNW-3800-TX clone-rtl8139 0xffff,0x8139 Cloned 8139 family drivers/net/via-rhine dlink-530tx 0x1106,0x3065 VIA 6102 via-rhine-6105 0x1106,0x3106 VIA 6105 dlink-530tx-old 0x1106,0x3043 VIA 3043 via6105m 0x1106,0x3053 VIA 6105M via-rhine-old 0x1106,0x6100 VIA 86C100A family drivers/net/w89c840 winbond840 0x1050,0x0840 Winbond W89C840F compexrl100atx 0x11f6,0x2011 Compex RL100ATX family drivers/net/sis900 sis900 0x1039,0x0900 SIS900 sis7016 0x1039,0x7016 SIS7016 family drivers/net/natsemi dp83815 0x100b,0x0020 DP83815 family drivers/net/fa311 fa311too 0x100b,0x0020 DP83815 family drivers/net/prism2_plx ma301 0x1385,0x4100 Netgear MA301 3c-airconnect 0x10b7,0x7770 3Com AirConnect ss1023 0x111a,0x1023 Siemens SpeedStream SS1023 correga 0x15e8,0x0130 Correga smc2602w 0x1638,0x1100 SMC EZConnect SMC2602W gl24110p 0x16ab,0x1100 Global Sun Tech GL24110P 16ab-1101 0x16ab,0x1101 Unknown wdt11 0x16ab,0x1102 Linksys WDT11 usr2415 0x16ec,0x3685 USR 2415 f5d6000 0xec80,0xec00 Belkin F5D6000 emobility 0x126c,0x8030 Nortel emobility family drivers/net/prism2_pci prism2_pci 0x1260,0x3873 Harris Semiconductor Prism2.5 clone hwp01170 0x1260,0x3873 ActionTec HWP01170 dwl520 0x1260,0x3873 DLink DWL-520 family drivers/net/ns8390 rtl8029 0x10ec,0x8029 Realtek 8029 dlink-528 0x1186,0x0300 D-Link DE-528 winbond940 0x1050,0x0940 Winbond NE2000-PCI winbond940f 0x1050,0x5a5a Winbond W89c940F compexrl2000 0x11f6,0x1401 Compex ReadyLink 2000 ktiet32p2 0x8e2e,0x3000 KTI ET32P2 nv5000sc 0x4a14,0x5000 NetVin NV5000SC holtek80232 0x12c3,0x0058 Holtek HT80232 holtek80229 0x12c3,0x5598 Holtek HT80229 surecom-ne34 0x10bd,0x0e34 Surecom NE34 via86c926 0x1106,0x0926 Via 86c926 wd - WD8003/8013, SMC8216/8416, SMC 83c790 (EtherEZ) ne - NE1000/2000 and clones 3c503 - 3Com503, Etherlink II[/16] family drivers/net/epic100 epic100 0x10b8,0x0005 SMC EtherPowerII smc-83c175 0x10b8,0x0006 SMC EPIC/C 83c175 family drivers/net/3c509 3c509 - 3c509, ISA/EISA 3c529 - 3c529 == MCA 3c509 family drivers/net/3c515 3c515 - 3c515, Fast EtherLink ISA family drivers/net/eepro eepro - Intel Etherexpress Pro/10 family drivers/net/cs89x0 cs89x0 - Crystal Semiconductor CS89x0 family drivers/net/depca depca - Digital DE100 and DE200 family drivers/net/sk_g16 sk_g16 - Schneider and Koch G16 family drivers/net/smc9000 smc9000 - SMC9000 family drivers/net/sundance sundance 0x13f0,0x0201 ST201 Sundance 'Alta' based Adaptor dfe530txs 0x1186,0x1002 D-Link DFE530TXS (Sundance ST201 Alta) family drivers/net/tlan netel10 0x0e11,0xae34 Compaq Netelligent 10 T PCI UTP netel100 0x0e11,0xae32 Compaq Netelligent 10/100 TX PCI UTP netflex3i 0x0e11,0xae35 Compaq Integrated NetFlex-3/P thunder 0x0e11,0xf130 Compaq NetFlex-3/P netflex3b 0x0e11,0xf150 Compaq NetFlex-3/P netel100pi 0x0e11,0xae43 Compaq Netelligent Integrated 10/100 TX UTP netel100d 0x0e11,0xae40 Compaq Netelligent Dual 10/100 TX PCI UTP netel100i 0x0e11,0xb011 Compaq Netelligent 10/100 TX Embedded UTP oc2183 0x108d,0x0013 Olicom OC-2183/2185 oc2325 0x108d,0x0012 Olicom OC-2325 oc2326 0x108d,0x0014 Olicom OC-2326 netelligent_10_100_ws_5100 0x0e11,0xb030 Compaq Netelligent 10/100 TX UTP netelligent_10_t2 0x0e11,0xb012 Compaq Netelligent 10 T/2 PCI UTP/Coax family drivers/disk/ide_disk ide_disk 0x0000,0x0000 Generic IDE disk support family drivers/disk/pc_floppy pc_floppy - Generic PC Floppy support
Even if your NIC does not appear in the list, it may still be supported if the chip is one of those supported. Many OEMs use chips from foundries. An exhaustive list of brand names is impossible. The best strategy is to read the number on the LAN controller chip on the board. The following drivers have notes in the src/drivers/net directory, please read them:
3c515.txt 3c90x.txt cs89x0.txt sis900.txt tulip.txt
User interaction options:
-DASK_BOOT=n
Ask "Boot from (N)etwork ... or (Q)uit? "
at startup, timeout after n seconds (0 = no timeout).
If unset, boot immediately using the default.
-DBOOT_FIRST
-DBOOT_SECOND
-DBOOT_THIRD
On timeout or Return key from previous
question, selects the order to try to boot from
various devices.
(alternatives: BOOT_NIC, BOOT_DISK,
BOOT_FLOPPY, BOOT_NOTHING)
See etherboot.h for prompt and answer strings.
-DBOOT_INDEX The device to boot from 0 == any device.
1 == The first nic found.
2 == The second nic found
...
BOOT_INDEX only applies to the BOOT_FIRST. BOOT_SECOND
and BOOT_THIRD search through all of the boot devices.
-DBAR_PROGRESS
Use rotating bar instead of sequential dots
to indicate an IP packet transmitted.
Boot order options:
-DBOOT_CLASS_FIRST
-DBOOT_CLASS_SECOND
-DBOOT_CLASS_THIRD
Select the priority of the boot classes
Valid values are:
BOOT_NIC
BOOT_DISK
BOOT_FLOPPY
Boot autoconfiguration protocol options:
-DNO_DHCP_SUPPORT
Use BOOTP instead of DHCP.
-DRARP_NOT_BOOTP
Use RARP instead of BOOTP/DHCP.
-DREQUIRE_VCI_ETHERBOOT
Require an encapsulated Vendor Class Identifier
of "Etherboot" in the DHCP reply
Requires DHCP support.
-DALLOW_ONLY_ENCAPSULATED
Ignore Etherboot-specific options that are not within
the Etherboot encapsulated options field. This option
should be enabled unless you have a legacy DHCP server
configuration from the bad old days before the use of
encapsulated Etherboot options.
-DDEFAULT_BOOTFILE="default_bootfile_name"
Define a default bootfile for the case where your DHCP
server does not provide the information. Example:
-DDEFAULT_BOOTFILE="tftp:///tftpboot/kernel"
If you do not specify this option, then DHCP offers that
do not specify bootfiles will be ignored.
NIC tuning parameters:
-DALLMULTI
Turns on multicast reception in the NICs.
Boot tuning parameters:
-DCONGESTED
Turns on packet retransmission. Use it on a
congested network, where the normal operation
can't boot the image.
-DBACKOFF_LIMIT
Sets the maximum RFC951 backoff exponent to n.
Do not set this unreasonably low, because on networks
with many machines they can saturate the link
(the delay corresponding to the exponent is a random
time in the range 0..3.5*2^n seconds). Use 5 for a
VERY small network (max. 2 minutes delay), 7 for a
medium sized network (max. 7.5 minutes delay) or 10
for a really huge network with many clients, frequent
congestions (max. 1 hour delay). On average the
delay time will be half the maximum value. If in
doubt about the consequences, use a larger value.
Also keep in mind that the number of retransmissions
is not changed by this setting, so the default of 20
may no longer be appropriate. You might need to set
MAX_ARP_RETRIES, MAX_BOOTP_RETRIES, MAX_TFTP_RETRIES
and MAX_RPC_RETRIES to a larger value.
-DTIMEOUT=n
Use with care!! See above.
Sets the base of RFC2131 sleep interval to n.
This can be used with -DBACKOFF_LIMIT=0 to get a small
and constant (predictable) retry interval for embedded
devices. This is to achieve short boot delays if both
the DHCP Server and the embedded device will be powered
on the same time. Otherwise if the DHCP server is ready
the client could sleep the next exponentially timeout,
e.g. 70 seconds or more. This is not what you want.
n should be a multiple of TICKS_PER_SEC (18).
Boot device options:
-DCAN_BOOT_DISK
Can boot from floppy/hd if bootimage matches the
pattern "/dev/fhsd*".
-DTRY_FLOPPY_FIRST
If > 0, tries that many times to read the boot
sector from a floppy drive before booting from
ROM. If successful, does a local boot.
It assumes the floppy is bootable.
Requires -DCAN_BOOT_DISK.
-DEMERGENCYDISKBOOT
If no BOOTP server can be found, then boot from
local disk. The accessibility of the TFTP server
has no effect, though! So configure your BOOTP
server properly. You should probably reduce
MAX_BOOTP_RETRIES to a small number like 3.
Boot image options:
-DTAGGED_IMAGE
Add tagged image kernel boot support (recommended).
-DAOUT_IMAGE
Add a.out kernel boot support (generic).
-DELF_IMAGE
Add generic ELF kernel boot support (recommended).
-DEL64F_IMAGE
Add generic ELF64 kernel boot support (useful for > 4GB disks).
-DWINCE_IMAGE
Add the ability to boot WINCE.... now only sis630 OK!
-DFREEBSD_PXEEMU
Add the ability to boot PXE images... only FreeBSD supported
-DX86_BOOTSECTOR_IMAGE
Add the ability to boot 512 byte x86 boot sectors
-DIMAGE_MULTIBOOT
Add Multiboot image support (currently only
for ELF images).
Without this, generic ELF support is selected.
-DIMAGE_FREEBSD
Add FreeBSD image loading support (requires at least
-DAOUT_IMAGE and/or -DELF_IMAGE).
-DFREEBSD_KERNEL_ENV
Pass in FreeBSD kernel environment
-DAOUT_LYNX_KDI
Add Lynx a.out KDI support
-DMULTICAST_LEVEL1
Support for sending multicast packets
-DMULTICAST_LEVEL2
Support for receiving multicast packets
-DDOWNLOAD_PROTO_TFTP
If defined, boots by TFTP (recommended).
-DDOWNLOAD_PROTO_NFS
If defined, boots from a NFS mount and disables
TFTP loading. Default is DOWNLOAD_PROTO_TFTP
if neither is defined.
-DDOWNLOAD_PROTO_SLAM
If defined, boots via Scalable Local Area Multicast.
-DDOWNLOAD_PROTO_TFTM
If defined, enables booting via TFTP Multicast mode.
-DSAFEBOOTMODE
Enables "Safe Boot Mode": Only boot images after verification
with public-key-cryptography, this is WORK IN PROGRESS
must be or'ed from one publickey storage method and
one nbi-digest method value
0 = store key in code (safeboot_key.h)
1 = store key in ROM somewhere else (to do)
0 = crypted digest in first 512 bytes -
as bytes 446...509 (compatible with most NBIs!?)
16 = crypted digest as ELF block (to do... Eric?)
So for now, only valid mode is "0"
Console options:
-DCONSOLE_FIRMWARE
Set for firmware/BIOS provided (default if nothing else is set).
Normally this is shows up on your CRT.
-DCONSOLE_SERIAL
Set for serial console.
-DCONSOLE_DUAL
Both of the above
-DCOMCONSOLE
Set port, e.g. 0x3F8.
-DCONSPEED
Set speed, e.g. 57600.
-DCOMPARM
Set Line Control Register value for data bits, stop
bits and parity. See a National Semiconditor 8250/
16450/16550 data sheet for bit meanings.
If undefined, defaults to 0x03 = 8N1.
-DCOMPRESERVE
Ignore COMSPEED and COMPARAM and instead preserve
the com port parameters from the previous user
of the com port. Examples of previous user are a BIOS
that implements console redirection, lilo and LinuxBIOS.
This makes it trivial to keep the serial port
speed setting in sync between multiple users.
You set the speed in the first user and the
rest follow along.
Obscure options you probably don't need to touch:
-DPOWERSAVE
Halt the processor when waiting for keyboard input
which saves power while waiting for user interaction.
Good for compute clusters and VMware emulation.
But may not work for all CPUs.
-DRELOCATE
After starting etherboot relocate to the top
of memory. This allows loading fairly arbitrary
rom images. This doesn't work with a couple of
drivers, e.g. lance.
BUS options:
-DCONFIG_PCI
Include support for devices using the pci bus.
-DCONFIG_ISA
Include support for devices using isa bus.
Markus Gutschke, gutschk AT math PERIOD uni-muenster PERIOD de
This documentation has been written and is copyrighted 1997 by Markus Gutschke <gutschk AT math PERIOD uni-muenster PERIOD de>. You are free to distribute this file as long as you do not change its contents. I appreciate comments and will consider them in future revisions. If you have any questions, comments, or suggestions, please also send carbon copies of your e-mail message to both Ken Yap <ken_yap AT users PERIOD sourceforge PERIOD net> and Gero Kuhlmann <gero AT gkminix PERIOD han PERIOD de>. I will happily include any of your extensions, but I would like to avoid the proliferation of different incompatible revisions of this document. If these conditions are a problem to you, then feel free to contact me.
Any computer that is either physically accessible or can remotely be contacted over a network is potentially threatened by attempts to circumvent its security measures. The PC architecture is especially insecure and using a BOOT-Prom can help preventing some of the more obvious attacks. On the other hand, it also enables some attacks that are not possible against machines that boot from local mass storage devices (floppy, harddisk, …). As a general rule, you can assume that it is impossible to protect your system from all conceivable attacks, but you can try to minimize the chance of an attack, try to minimize the seriousness of the damage caused and try to help in detecting attacks at the earliest possible moment. This text discusses some of the issues involved and tries to raise awareness of security problems; it cannot provide generic solutions to all of these problems, but should help you in appreciating the need for proper administration and regular security updates.
The PC architecture was never designed with security considerations in mind. Running an operating system such as DOS or Windows, allows the user full control over the hardware. There are no effective measures for preventing him from modifying data on local mass storage devices, reading confidential data that is stored locally, installing trojan horses and programs that intercept user input, monitoring all data packets that are sent on the local ethernet segment, sending ethernet packages with faked authorization information, and a whole lot of other potentially dangerous actions.
Modern operating systems and suitable hardware extensions make these attacks more difficult, but as long as the user can still launch arbitrary programs that have full hardware access, there is not much protection that can be achieved in this way. Therefore, the most important security measures are those that prevent a malicious user from executing programs from arbitrary external sources.
The PC must be physically protected, so that there is no way of replacing the harddrive (either for reading its contents or for installing compromised software), installing a modified system BIOS (if your system has a Flash BIOS, then make sure that it is always write protected and that write protection actually works!), connecting it to a different network, removing extra hardware that offers security features, or performing some other hardware modification.
If the PC offers exchangeable mass storage devices (floppy, ZIP drive, CD-ROM, …), the system must be configured to never boot from these devices.
This is not as easy as it might sound. Most motherboards come with a system BIOS which offers back-doors to their password. So configuring the BIOS to never boot from exchangeable devices, will not prevent any determined hacker from modifying this setting. These generically accepted passwords might not be known to your average users, but you can assume that even a poorly informed hacker will know about them. Besides, if your system allows for reading the contents of the CMOS memory chip (e.g. by starting a suitable DOS program such the debugger which ships with DOS), then the password can be computed from this data. While you should still make sure, that your BIOS has password protection, this is only to be considered as a mild deterrent.
A more useful protection is achieved by installing extra firmware, which requires a password before booting from a local device. This firmware should be written in a way which prevents the system BIOS from disabling it. This is the default configuration for the “etherboot” BOOT-Prom, but it might still be circumvented, if your system BIOS allows for disabling certain memory areas from being scanned for ROMs. If this is the case, then complain to your system vendor and replace the machine; it is unsuitable for being used in a publically accessible place. Also, in a security conscious environment, there must be no way of escaping from the control of the BOOT-Prom; this means, that you must not enable the “-DEMERGENCYDISKBOOT” option when compiling the “etherboot” software and you must never offer an empty image name in the image menu (c.f. README.VendorTags). If you want to offer booting from a local device, then specify the full device name and either enable the “-DFLOPPY” option or store a boot image (as generated by “mknbi-blkdev”) under this name on the TFTP server.
It might be a good idea to install non-functional bootcode in the master boot record of your harddisk and install any locally required boot code in the boot sectors of the individual partitions. Both “etherboot” and “mknbi-blkdev” know how to boot from partitions such as “/dev/hda1” (first primary partion) or “/dev/hdb5” (first logical partion on the second harddrive).
If you have the choice, then do not offer operating systems which come without effective password protection and virtualization. This basically rules out all of the following: DOS, Windows, Win95, …
You should be aware of the fact, that offering one “dangerous” operating system, makes all other operating systems vulnerable as well. A noteworthy example is the availability of tools which allow an arbitrary DOS user to read and modify the contents of a Linux harddisk partition (similar tools are supposedly available for accessing NT partions).
Password protected BOOT-Proms are a considerable improvement over the standard security measures offered by the PC architecture, but they are still vulnerable to a variety of attacks. Most of these attacks are related to the weaknesses of the BOOTP and TFTP protocol and these issues are discussed in another section of text.
As the BOOT-Prom cannot store the passwords locally, it has to request them from the BOOTP/TFTP server. The BOOTP and TFTP protocols do not allow for any elaborate challenge/response authorization scheme. Thus the BOOT-Prom requests the password from the server and subsequently compares it with the password as input by the user. As packets transmitted on the ethernet can easily be monitored, the server sends a MD5 message digest (as invented by Ron Rivest/“RSA Data Security, Inc.”) of the actual password. The BOOT-Prom computes the MD5 value for the user input and compares these two values. It is generally believed that there is no way of computing a valid plain text from a known MD5 message digest, other than comparing it against all conceivable input texts. Thus, this approach is still vulnerable against dictionary attacks. You should aim for using long passwords (although, anything beyond 20 characters is unlikely to considerably improve the security of the password) which are not listed in any dictionary. Make sure that these passwords are memorized and not available in un-encrypted form. Replace the passwords regularly and do not offer more menu entries in the BOOTP data than are absolutely necessary.
If you have to offer DOS or a related operating system, then do not fool yourself into believing that you can install security software in one of its configuration files. All of these mechanisms can easily be avoided. In many cases, even average users can figure out how to do this.
There are a variety of ways that allow for booting Linux in single user mode. The most common techniques involve passing a suitable option on the kernel command line (i.e. “single”) or crashing the filesystem by power cycling the machine; this in turn will result in fsck being invoked at the next system start, which will sometimes drop you into single user mode.
Some Linux distributions do not require a password when entering single user mode. While this makes system administration somewhat easier, it is a considerable security problem. Make sure, that your system does not suffer from it.
For other security problems with running insecure programs under Linux or using poorly configured distributions, refer to the Usenet newsgroups, security mailing lists and choose a distribution whose manufacturer frequently releases security fixes. It is a fallacy to assume that the unavailability of patches implies the security and correctness of a software application; as a rule of thumb, a manufacturer who releases more patches than a different one, probably cares more about the security of your system than the latter. This also applies to operating systems other than Linux!
==== ETHERNET AND ITS PROTOCOLS The ethernet is extremely vulnerable to attacks from malicious users. Anybody who can gain direct access to an ethernet segment, can easily monitor all traffic and inject forged data. This is very dangerous, because many protocols transfer data either un-encoded or in easily decipherable form. Also, authorization is often based on the assumption that the return address or a session id can be trusted, but this is no longer true if users gain unlimited access to the ethernet; it does not really matter if this access is achieved by having physical control over part of the network or by running a compromised or inherently insecure operating system. There are various attacks from machines that are not directly connected to your ethernet segment, but the majority of them can be prevented by installing and maintaining a properly configured firewall. For more information, you should regularly monitor security related newsgroups and mailinglists.
BOOTP and TFTP offer almost no security whatsoever. They basically provide their information to anybody who asks and solely rely on the assumption that your network is configured to not make the server world-accessible. If you install BOOTP gateways, then this assumption is seriously violated. Also, TFTP server are usually accessible from just about everywhere. You can try to diminish the impact of this problem by blocking BOOTP and TFTP packets from leaving or entering your network segment, but this will never be a completely secure solution.
Thus you should always assume that all of the files that your BOOTP and TFTP server offer are world readable. They must not contain any sensitive data. Also, the TFTP daemon must be configured to only allow access to selected files. Running it in a chroot'd environment might be a very good idea.
The BOOTP protocol is vulnerable against somebody else impersonating as a BOOTP server. While security aware operating systems, prevent non-privileged users from starting their own BOOTP servers, other operating systems do not allow this. This means, if any of your users can launch an arbitrary program under an insecure operating system on an arbitrary machine connected to your ethernet segment, then they have full control over the BOOTP boot process.
While NFS is very convenient for installing diskless machines, it provides almost no security. Data is transmitted unencrypted and authorization is solely based on the identity of IP addresses. Anybody who can forge ethernet packets, has full access over any data that is available via NFS. While there are protocol extension that try to address these shortcomings, I am not aware of any solution for Linux based machines. This means, you have to assume that all exported filesystems are freely read- and writable. Bear this in mind when deciding which data you intend to export.
Telnet and rlogin do not usually come with any effective protection other than simple password schemes. Data and even the password is transmitted as plain text. There are commonly available programs that constantly monitor the network for packets that contains passwords. Fortunately, the security of these protocols can be vastly improved by replacing them with the Secure Shell protocoll (http://www.cs.hut.fi/ssh). Preferably, all telnet and rlogin servers and clients should be removed from all machines.
X provides some security when run over a network, but the scope of it is limited and exploits can easily be devised. At the very least, you should make sure that the xauth protocol is used as opposed to the vastly inferior xhost protocol. A better solution is provided by routing all X connections through a secure shell session. This does not only provide more reliable authentication, but it also encrypts all data.
While this text cannot do more than barely scratch the surface, it should help you in locating some of the more vulnerable sub-systems of your networks and your computers. It does not aim for completeness, but if you think that there is a topic which should be mentioned or if you want to update an entry, then please to contact me.
Markus Gutschke, gutschk AT math PERIOD uni-muenster PERIOD de with changes by Ken Yap, ken_yap AT users PERIOD sourceforge PERIOD net
This documentation has been written and is copyrighted 1996,97 by Markus Gutschke <gutschk AT math PERIOD uni-muenster PERIOD de>. You are free to distribute this file as long as you do not change its contents. I appreciate comments and will consider them in future revisions. If you have any questions, comments, or suggestions, please also send carbon copies of your e-mail message to both Ken Yap <ken_yap AT users PERIOD sourceforge PERIOD net> and Gero Kuhlmann <gero AT gkminix PERIOD han PERIOD de>. I will happily include any of your extensions, but I would like to avoid the proliferation of different incompatible revisions of this document. If these conditions are a problem to you, then feel free to contact me.
RFC1533 allows for vendor-specific extensions to the BOOTP protocol. It defines that all tags in the range 128 thru 254 are set aside for site-specific extensions. Common implementations of DHCP daemons can assign arbitrary null-terminated character strings to these tags.
This is a list of the tags that are currently used by Etherboot. Tag 128 and 129 are handled by Etherboot. The other tags are handled by an external menu program, generated using mkelf-menu. This is changed behaviour from 5.0, where the menuing code was part of Etherboot. As a general rule, you should never fill out any of the other tags, unless you positively know that your BOOT-Prom supports the extension or ignores this particular tag: TAG 128
this is a six-byte hexadecimal entry. The first four bytes have to be the magic number E4 45 74 68; if this magic cannot be found, then none of the other vendor tags are valid! The fifth byte is the major version number and the sixth byte is the minor version number of this protocol extension. The current version is 0.0; the BOOT-Prom can assume that incompatible changes increase the major version number. Mere extensions to the existing protocol, increase the minor version number. If the BOOT-Prom code has been written in a way that anticipates future extensions, then it is acceptable to honor the vendor tags even though, the minor version number does not match exactly. Before making a change, that requires updating the major version number, you should contact all of the persons that are listed at the top of this document. TAG 129 the BOOT-Prom uses this tag for passing a user-provided command line to Linux. Anything in this tag will be appended to the kernel parameters already in the boot image created by mkelf. TAG 160 a string that contains a colon separated list of “parameter=value” pairs. Currently, these parameters are only used to control the behavior of an interactive menu for selecting different boot images; future extensions are quite likely: timeout after this many seconds, the default image will be loaded. If no 'timeout' has been set, then the program will wait indefinitely. default either an integer 'n' in the range 0 thru 15 or 192 thru 207, selecting the default image. If 'n' is in the first range, it refers to the 'n'th menu entry; if it is in the later range, it refers to the entry with the tag number 'n'. This distinction is important, if the list of images contains gaps. If no value has been set, then the image with the lowest tag number will be the default image. TAGS 161 thru 174 these tags are currently unused, but they should be allocated for purposes that resemble the function of tag 160. TAG 175 the BOOT-Prom uses this tag for telling the DHCP server which NIC driver it is using. The DHCP server can then modify the “filename” field in the DHCPACK packet in order to direct the BOOT-Prom to download an appropriate kernel image. TAG 176 the BOOT-Prom uses this tag for telling the loaded operating system, which of the entries in tags 192 to 207 has been selected by the user. As this tag is used internally, the DHCP daemon must not assign any value to it! TAGS 177 thru 183 these tags are reserved for passing information from the BOOT-Prom to the boot image. Under no circumstances should the DHCP daemon assign any of these entries. The format of these parameters is yet to be discussed. TAGS 184 thru 191 up to eight zero-terminated character strings can be used for displaying a “message of the day”. If you need to display more than eight lines, you can embed suitable CR/LF pairs. If you fully exploit that feature, you can display a complete 80×24 screen of information, but you should be aware that subsequent output might scroll part of a long message. The BOOT-Prom can optionally be configured to interpret some ANSI escape sequences. The ANSI emulation currently knows about these commands:
Display attributes
Code Effect
<esc>[0m normal text
<esc>[1m high-intensity on
<esc>[21m high-intensity off
<esc>[5m blinking on
<esc>[25m blinking off
<esc>[7m reverse video on
<esc>[27m reverse video off
<esc>[3xm set foreground color:
<esc>[4xm set background color. x can be:
0 - black 4 - blue
1 - red 5 - magenta
2 - green 6 - cyan
3 - yellow 7 - white
<esc>[=xh set video mode
0 - 40x25 mono (text) 13 - 40x25 16colors (gfx)
1 - 40x25 16colors (text) 14 - 80x25 16colors (gfx)
2 - 80x25 mono (text) 15 - 80x25 mono (gfx)
3 - 80x25 16colors (text) 16 - 80x25 16colors (gfx)
4 - 40x25 4colors (gfx) 17 - 80x30 mono (gfx)
5 - 40x25 mono (gfx) 18 - 80x30 16colors (gfx)
6 - 80x25 mono (gfx) 19 - 40x25 256colors(gfx)
Cursor control
Code Effect <esc>[r;cH move cursor to row r and column c <esc>[r;cf move cursor to row r and column c <esc>[rA move cursor up r rows <esc>[rB move cursor down r rows <esc>[cC move cursor right c columns <esc>[cD move cursor left c columns <esc>[?7l turn off line wrap <esc>[?7h turn on line wrap <esc>[J clear screen and home cursor <esc>[K clear to end of line <esc>[s save the cursor position <esc>[u return cursor to saved position
Extended features
Code Effect
<esc>[a;b;c;d+<data>
draw pixel data. Use one byte per pixel.
Colors are encoded as shown above. In text
mode, graphics is approximated by outputting
suitable characters. Parameters differ
depending on the number of parameters
passed:
cnt
"cnt" data bytes follow. They will be
drawn to the right of the last graphics
position.
rle;col
the next "rle" pixels have the value
"col". They will be drawn to the right
of the last graphics position. No data
bytes follow.
x;y;cnt
"cnt" data bytes follow. They will be
drawn relative to the top left corner of
the text cursor with an offset of (x/y).
x;y;rle;col
the next "rle" pixels have the value
"col". They will be drawn relative to
the top left corner of the text cursor
with an offset of (x/y). No data bytes
follow
you usually do not have to enter these
values manually, but you should use a tool
such as "ppmtoansi" which is shipped with
your BOOT-Prom or available from the contrib
directory of the "etherboot" package.
<esc>[a;b;c;d-<data>
same as above, but pack pixels into three
bits. The first pixel is stored in the three
most significant bits of the first data
byte.
Note that you usually have to specify any control characters directly (rather than in hex form) in your /etc/dhcpd.conf file.
TAGS 192 thru 207 these tags define all of the valid boot images and override any settings that are given with the filename field in your /etc/dhcpd.conf. It is allowed to leave gaps in the list. This has an impact on how the default image will be selected. All entries are of the form
label:server:gateway:filename:passwd:flags:cmdline
For future extensibility, it is permitted to append an arbitrary amount of other colon separated entries as long as the limit of 255 characters per tag is not exceeded. Non-existent entries can be left empty. This means that the default value for this particular entry will be used. Trailing colons can be omitted.
label this is the text string that is displayed to the user. It can contain arbitrary characters, except for a colon. Embedding arbitrary control characters is not recommended, but you might be able to include ANSI escape sequences (if enabled in the ROM) for changing text attributes as long as you restore the attributes at the end of the string. It probably does not make very much sense to leave this entry empty. server (This field is no longer supported. Its contents will be ignored.) gateway (This field is no longer supported. Its contents will be ignored.) filename name of the boot image that has to be loaded by TFTP. If this entry is omitted, then the machine boots locally from disk. If enabled in the BOOT-Prom, you can specify pseudo-filenames for booting from a local blockdevice (floppy, harddisk, …); these filenames have to match the pattern “/dev/[fh]d*”. If the BOOT-Prom does not have support for these pseudo-filenames, you can still boot from blockdevices by storing an boot image as generated by mknbi-blkdev under the name of the desired blockdevice (symbolic links will do). In Etherboot 4.6.2 and later, a - in this field means use the filename specified in the BOOTP/DHCP reply. This saves on menu size. passwd MD5 message digest of the password. If this entry is omitted, then no password is required for loading this image. Support for passwords is optional and might not be compiled into the ROM image. For generating the MD5 message digest, you can use freely available tools such as “md5sum”. C.f. the flags entry for controlling the behavior of passwords. flags flags are used for controlling some aspects of how the BOOT-Prom code behaves. All flags are a string of decimal digits followed by a letter; multiple flags can be concatenated. If this entry is omitted, then a default value of “1i1p” is assumed. Currently, these flags are defined: 0i booting this image does not require a password; the contents of the password entry is ignored unless some other feature (such as the flag “2p”) requires it. 1i booting this image requires a password. If the password entry is omitted, or no password support is available in the BOOT-Prom, then this flag is ignored. 0p the user cannot enter a command line for passing parameters to the loaded image, even if this feature has been enabled when compiling the BOOT-Prom. N.B. this does not affect the cmdline entry as described below! 1p the user does not get prompted for passing parameters to the loaded image, but he can explicitly request the prompt (e.g. by pressing a modifier key while selecting an image from the menu). If the password entry is not omitted, then the password has to be entered. Both parameter passing and password validation can be disabled when compiling the BOOT-Prom. 2p the user always gets prompted for passing parameters to the loaded image. If the password entry is present and password support has been enabled in the BOOT-Prom, then the password has to be entered. 3p the user always gets prompted for passing parameters to the loaded image. No password is required. cmdline the contents of this entry is appended to the end of tag 129 from the DHCP record, provided tag 129 exists. This feature is unaffected by the “p” flags. Passing parameters currently does not make sense for any operating system other than Linux and is silently ignored for other operating systems. As it is not legal to enter colons as part of an entry, you have to escape them by writing “~c” instead. This also means, that all tilde characters have to be escaped by writing “~~”. As some DHCP daemons do not allow for entering a backslash in a character string, the escape sequence “~b” inserts a backslash character. Currently, all other escape sequences are undefined. (This example has not yet been translated to DHCPD syntax, sorry.) For demonstration purposes, I attached an annotated excerpt from my “bootptab” illustrating some of these techniques. In the following the character sequence ESC should be replaced by the ASCII escape character. Also the 8-bit characters have been changed to 7-bit approximations due to SGML tool limitations. To get the original codes, use this table: top left corner, char 201 (decimal); horizontal bar, char 205; top right corner, char 187; vertical bar, char 186; bottom left corner, char 200; bottom right corner, char 188.
# # The MOTD (message of the day) can contain arbitrary characters, that # the PC is capable of displaying. Here we use 8bit characters for # drawing a border around the message; also we change the foreground # color to red (this assumes that the BOOT Prom has support for ANSI # escape sequences): # .motd:\
:T184="ESC[31m":\
:T185="+------------------------------------------------------+":\
:T186="| This is an experimental release of the new BOOT-Prom |":\
:T187="| code. It supports a couple of non-standard vendor |":\
:T188="| extensions. |":\
:T189="+------------------------------------------------------+":\
:T190="ESC[37m":
# # Alternatively, the MOTD can be stored in an external file; this # requires that you enabled ANSI support in the BOOT Prom! For more # advanced configurability, you should explore the feature of the # patched tftpd daemon (as available in the contrib directory) to # execute shell scripts and use the output as the file contents. # # .motd:\ # :T184=“ESC[31mLoading message of the day…ESC[37mESC['/etc/motd'#”: #
# # We use the “template” feature of modern versions of “bootp” in order # to group common entries. Unfortunately, you cannot use more than one # “tc” entry per (pseudo-) host. Pseudo hostnames should begin with a # leading period character. # # All entries are kept as generic as possible. This ensures that they # will keep working even when the network topology is changed. Leaving # the server IP address and the gateway IP address empty, should # ensure that booting works even when we go thru “bootpgw” gateways. # # “Technicolor” special effects are achieved by changing the # foreground text color of the individual labels. You could even embed # small icons after switching to graphics mode. C.f. “linux-logo.ansi” # for an example; this will not work, if your BOOT Prom does not have # support for ANSI escape sequences. # # Passing boot-time parameters to the Linux kernel, requires the # password “Penguin”. # # Booting from the local disk requires the password “Joshua”. If the # BOOT-Prom does not have support for booting from local block devices # (floppy, harddrive, …), then you can either omit the filename # (c.f. README.Security for potential security problems) or your TFTP # server has to provide a boot image that has been generated by # mknbi-blkdev. # .imagemenu:\
:tc=.motd:\
:T128=E44574680000:\
:T160="timeout=30:default=207:":\
:T192="ESC[32mLinux 2.0.27ESC[37m:::/tftpdir/image-linux:99625fa1cac27bb6a2b33b7638afe47:0i1p":\
:T193="ESC[33mDOS 6.2ESC[37m:::/tftpdir/image-dos":\
:T207="ESC[34mLocal DiskESC[37m:::/dev/hda:85b103482a20682da703aa388933a6d8":
# # When using more than a handful of vendor parameters, we have to # specify an extension file “ef”. If you are very careful, then it is # possible to use one extension file for several hosts. Don't forget # to run “bootpef” after editing the “bootptab”, and make sure that # you “chroot” into the proper directory, if applicable. # .default:\
:tc=.imagemenu:\
:bf=tftpdir/image-rom:\
:hd=:\
:ht=ethernet:\
:sm=255.255.255.0:\
:vm=auto:\
:ef=extension.bootp:
# # Ideally, hosts differ only with respect to their ethernet hardware # ID and IP number. We let the “bootpd” look up the correct IP number. # thalamus:tc=.default:ha=00400529C11B:ip=thalamus: cortex: :tc=.default:ha=0000C0531A24:ip=cortex:
Here is an example DHCP specification that uses an external menu program. It also illustrates the use of - in the filename portion of the menu options to eliminate needless repetition.
# per host setup host 192.168.40.203 {
# MAC and IP addresses
hardware ethernet 00:60:08:0d:a9:84;
fixed-address 192.168.40.203;
# default file to boot, common append options, default menu selection and timeout
filename "/tftpboot/menu.nb";
option option-128 E4:45:74:68:00:00;
option option-129 "ramdisk_size=16000 vga=6";
option option-160 "timeout=10:default=192";
option option-184 "^[['/tftpboot/thinlinux/1.0-alpha-025/motd'#";
# menu selections, specify filename or "-" to use default filename specified above
option option-192 "test1:::-:::nfs=xterm";
option option-193 "test2:::-:::nfs=shell";
option option-194 "test3:::-:::nfs=other";
}
For ISC DHCPD 3.0 Beta 2 Patchlevel 18 and above the syntax above is no longer accepted and a new syntax is in operation according to this note in the Changelog:
Use unparsable names for unknown options. WARNING: this will break any configuration files that use the option-nnn convention. If you want to continue to use this convention for some options, please be sure to write a definition, like this:
option option-nnn code nnn = string;
You can use a descriptive name instead of option-nnn if you like.