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-
-Backup-With-MSDOS mini-HOWTO
-
-
-
-----
-
-!!!Backup-With-MSDOS mini-HOWTO
-
-!!Christopher Neufeld, neufeld@physics.utoronto.cav, 5 August 1997
-
-
-----
-''This HOWTO describes how to use a Linux-compatible tape drive
-installed on an MS-DOS machine to back up the filesystem of a Linux
-machine.''
-----
-
-
-
-
-!!1. Preface/Introduction
-
-
-
-
-!!2. The technique
-
-
-
-
-!!3. Notes
-
-
-
-
-!!4. Copyright
-----
-
-!!1. Preface/Introduction
-
-
-Earlier I posed the question on the Net, how does one back up a Linux
-machine to a Colorado Jumbo 250 tape drive on an MS-DOS machine.
-From the email I received,
-it seems that this is a frequently pondered problem.
-Now that I've figured it out, I'm posting the method.
-If anybody wants to massage this into a HOWTO document, let me know.
-I should thank Jim Nance
-(
-jlnance@isscad.com)
-for pointing out that an MS-DOS machine need not always be an MS-DOS machine.
-This technique should also work for any other tape drive
-supported by the ftape module, and for SCSI tape drives with suitable
-obvious changes (i.e. substituting /dev/st0 for /dev/ftape).
-
-
-The criteria I set were that the resulting setup should be as secure
-as possible and should be fairly simple, and take up little or no space
-on the MS-DOS machine's hard drive. It should also be capable of
-recovering from the worst system corruptions, up to and including the
-theft of the hard disk, requiring a restore to a bare Linux file system.
-The technique described
here uses no hard drive space on the MS-DOS
-machine, though it requires that that machine be assigned an IP#.
-You will need three formatted, blank 1.44MB diskettes.
-----
-
-!!2. The technique
-
-
-Throughout this description I will refer to two machines as ``msdos''
-and ``linux''. ``msdos'' is the name of the machine
-which has the tape drive and is usually running MS-DOS.
-``linux'' is the Linux machine whose disk
-you are trying to back up or restore to the tape drive.
-For simplicity I will refer to the first machine as ``msdos''
-even when it is booted into and running Linux.
-Further, all path names in this document should be considered
-to be relative to the Linux machine with the Search-And-Rescue (SAR)
-disks mounted somewhere on the system.
-That means that the file /etc/passwd is the password file for
-your Linux machine's hard drive, while, for instance,
-/tape144/etc/passwd is the corresponding file on the floppy disk.
-
-
-
-
-
-I am using Karel Kubat's backup scripts, version 1.03, available at
-
-ftp://sunsite.enc.edu:/pub/Linux/system/Backup/backup-1.03.tar.gz
-Throughout this document I will refer to these simply as
-``the backup scripts''.
-You do not have to use these scripts for your own backups to tape.
-I like these scripts as they use afio to form
-an uncompressed archive of compressed files,
-rather than a compressed archive of uncompressed files.
-The former is much safer if there is a media read error during the restore.
-I understand that Karel is no longer supporting backup,
-and now has produced 'tob', or tape oriented backup.
-While I haven't tried the new package myself,
-it cannot make a significant difference to the procedure outlined here.
-
-
-First of all, obtain the ftape module. It is a part of all modern kernels,
-but if you are using an older kernel you can find the module at:
-
-ftp://sunsite.unc.edu/pub/Linux/kernel/tapes/ftape-2.05.tar.gz
-Next, get a Slackware boot disk
-(I got the net disk, but it doesn't make much difference) and
-the tape144 root disk,
-and put the images onto 3"1/2 floppies.
-
-
-The ftape module will only work
-if it is installed in the kernel which was running when you compiled it.
-I could not get it to work with the ftape.o module on
-the tape144 root disk,
-I think because that module has been stripped of symbols and won't install.
-So, you now have to make a new kernel with network and ftape support,
-and if you're running an old kernel, a new ftape.o.
-Read the directions which ship with the ftape archive for
-directions at this stage.
-Remember that the kernel you compile must support the Ethernet cards
-on both the Linux machine and the MS-DOS machine.
-
-
-Copy the newly created kernel image over top of the one on the Net boot disk.
-Use /bin/cp, do not create a boot disk with the ``dd''
-command as you would to create a bootable kernel image.
-Write protect the boot disk, and label it: SAR#1.
-
-
-Now, mount the tape144 root disk.
-I'll assume that the mount point is /tape144,
-to avoid confusion in file names.
-We need to free some space on it, so delete the following files:
-
-
-/tape144/bin/dialog
-/tape144/bin/elvis
-/tape144/bin/vi
-/tape144/boot/ftape.o
-
-
-
-
-Now, create a new file:
-
-
-/tape144/etc/exports
-
-
-which contains the following line:
-
-
-/mnt msdos(ro)
-
-
-Where ``msdos'' should be replaced with the name or IP#
-of the MS-DOS machine which has the tape drive installed.
-
-
-Next, so that you don't have to rely on a name server,
-add lines to the file /tape144/etc/hosts with
-the names and IP numbers of the Linux and MS-DOS machines.
-For instance, mine contains the following two lines:
-
-
-128.100.75.114 caliban.physics.utoronto.ca caliban caliban.physics
-128.100.75.111 ariel.physics.utoronto.ca ariel ariel.physics
-
-
-
-
-Now, there's some sort of problem with the inetd configuration.
-We have to put the full path name of the rsh daemon in it.
-Change line 19 of /tape144/etc/inetd.conf to read:
-
-
-shell stream tcp nowait root /usr/etc/tcpd /usr/etc/in.rshd
-
-
-
-
-Add local net routing information to /tape144/etc/rc.d/rc.inet1
-to enable the MS-DOS machine to use the network.
-The format of this depends on your network configuration,
-you can just copy the appropriate format out of your Linux
-/etc/rc.d/rc.inet1.
-For my network, the lines that have to be added are:
-
-
-/etc/ifconfig eth0 128.100.75.111 broadcast 128.100.75.0 netmask 255.255.255.
-/etc/route add -net 128.100.75.0 netmask 255.255.255.
-
-
-The IP# in the ifconfig entry is that of the MS-DOS machine.
-
-
-Now, copy this file into /tape144/etc/rc.d/rc.inet1-l,
-and change the IP# in the new file to reflect that of
-the Linux machine rather than the MS-DOS machine.
-
-
-Next, clip out lines 3 to 11 of /tape144/etc/rc.local.
-That's an if statement which executes the rc.inet* files.
-We don't want this to happen during the bootup.
-
-
-Create a new file: /tape144/root/.rhosts containing the line:
-
-
-linux root
-
-
-where, again, ``linux'' is replaced with the full machine name
-(including domain) or the IP# of the Linux machine.
-
-
-Fill in the password field in /tape144/etc/passwd
-for the root login to keep people from logging onto the MS-DOS machine
-while you're doing the backup.
-You can do this by copying the corresponding field from your Linux machine's
-/etc/passwd file.
-
-
-Copy /usr/bin/rsh into /tape144/usr/bin.
-
-
-Copy the following files from /usr/etc into /tape144/usr/etc:
-
-
-in.rshd
-rpc.mountd
-rpc.nfsd
-rpc.portmap
-services
-tcpd
-
-
-
-
-Create a new script, /tape144/bin/tapesetup,
-which consists of the following:
-(change ``linux'' to reflect your Linux machine name).
-
-
-#! /bin/sh
-/bin/sh /etc/rc.d/rc.inet1
-/bin/sh /etc/rc.d/rc.inet2
-/bin/mount linux:/nfs /mnt
-/bin/insmod /mnt/ftape.o
-
-
-Note that newer kernels will not require the insmod line.
-
-
-Next, create another new script, /tape144/bin/msdosset, as follows:
-(change ``linux'' to reflect your Linux machine name).
-
-
-#! /bin/sh
-/bin/sh /etc/rc.d/rc.inet1
-/bin/sh /etc/rc.d/rc.inet2
-mount linux:/mnt /mnt
-/bin/insmod /mnt/ftape.o
-
-
-As above, newer kernels will not require the insmod line.
-
-
-Create a readable file, /tape144/root/notes,
-which contains this helpful information for use in full recovery:
-
-
-For a full recovery to a trashed hard disk,
-boot the Linux machine with the SAR disks #1 and #2
-then type the following:
-/bin/sh /etc/rc.d/rc.inet1-l
-/bin/sh /etc/rc.d/rc.inet2
-/usr/etc/rpc.portmap
-/usr/etc/rpc.mountd
-/usr/etc/rpc.nfsd
-Next, insert SAR disk #3 and type:
-mount /dev/fd0 /mnt
-Create a new mount point, with:
-mkdir /mnt2
-and mount your Linux hard disk partition on this point.
-You may have to reformat the partition first, if so,
-follow the directions in the Linux Installation HOWTO.
-The SAR disks contain all the files necessary to do the reformat.
-Finally, use disks SAR#1 and SAR#2 to boot up
-the MS-DOS machine and run the /bin/msdosset script on that machine.
-It will take about a minute to run that script because it is getting
-an NSF file from a floppy drive, so be patient.
-Now, recover the tape to /mnt2 on the Linux machine.
-
-
-
-
-If you are using the backup scripts you will need to
-copy 'afio' into the /tape144/local/bin subdirectory.
-It is not necessary to have the rest of the backup script files
-on the recovery disks, an archive can be recovered using only 'afio' and 'gzip'.
-
-
-I was unable to use the backup scripts as they come shipped.
-The tape archive appears to build cleanly, but it is unrecoverable.
-I found that removing the block size and conversion statements fixed it.
-Here is the patch to the ``netbackup'' script.
-Apply this patch to the Linux machine's hard disk copy of 'netbackup'
-as well as to the copy on the SAR disks.
-
-
-*** netbackup.orig Mon Jan 9 17:22:32 1995
---- netbackup Mon Jan 9 17:23:25 1995
-***************
-*** 35,41 ****
-"'mknod", devname, "p'");
-exec ("su -", USERNAME, "-c",
-"'rsh ", REMOTE_HOST,
-! "\"dd", "of=" REMOTE_DEVICE, "obs=20k", "conv=sync\"",
-"<", devname,
-"'&"
-);
---- 35,41 ----
-"'mknod", devname, "p'");
-exec ("su -", USERNAME, "-c",
-"'rsh ", REMOTE_HOST,
-! "\"dd", "of=" REMOTE_DEVICE, "\"",
-"<", devname,
-"'&"
-);
-***************
-*** 50,56 ****
-"'mknod", devname, "p'");
-exec ("su", USERNAME, "-c",
-"'rsh ", REMOTE_HOST,
-! "\"dd", "if=" REMOTE_DEVICE, "ibs=20k", "conv=sync\"",
-">", devname,
-"'&"
-);
---- 50,56 ----
-"'mknod", devname, "p'");
-exec ("su", USERNAME, "-c",
-"'rsh ", REMOTE_HOST,
-! "\"dd", "if=" REMOTE_DEVICE, "\"",
-">", devname,
-"'&"
-);
-
-
-
-
-You have now finished your SAR disk #2.
-Write protect it.
-
-
-Next, mount a clean, formatted disk
-(create it with fdformat and mkfs).
-Copy the ftape.o file onto it, and label it SAR#3.
-For some reason things go badly if you write protect this disk,
-so leave it write-enabled.
-
-
-On the Linux machine, create a new directory for NFS file serving.
-I made a directory:
-
-
-/nfs
-
-
-Put the ftape.o (unstripped, about 500+ kB) into this subdirectory.
-Create an entry in your Linux's exports file /etc/exports:
-
-
-/nfs msdos(ro)
-
-
-Note that all files in your NFS directory and it's subdirectories
-are not secure.
-Somebody else could boot the MS-DOS machine into Linux with
-his own boot disks and mount this directory,
-so be certain that you don't put anything sensitive in your NFS subdirectory.
-
-
-Restart your NFS daemons, rpc.mountd and rpc.nfsd.
-They don't seem to take kindly to a SIGHUP restart,
-so kill them and reinvoke them.
-If you're not activating these daemons in your /etc/rc.d/rc.inet2
-you might want to do so now.
-
-
-OK, now we're all set to back up and recover.
-To make a full backup from the Linux machine,
-boot the MS-DOS machine with SAR#1.
-When prompted for the second disk, load SAR#2. Log in as root,
-and execute the script: /bin/tapesetup.
-Log out of the MS-DOS machine.
-If you're using the backup scripts, the netbackup command will now work.
-You can also use the ``-f msdos:/dev/ftape'' switch on GNU
-tar, cpio, or mt, and make your backup this way.
-If you have a backup program,
-which is only capable of writing to a local file,
-do the following.
-Assume that the backup program is called ``localbackup'' and
-writes to the file represented by its command line argument:
-
-
-mknod /tmp/tapepipe p
-rsh msdos dd of=/dev/ftape < /tmp/tapepipe &
-localbackup /tmp/tapepipe
-
-
-when it's done, delete /tmp/tapepipe.
-
-
-Recovering to a live Linux machine:
-the netbackup script, tar, cpio,
-and so on will all work without special actions on the part of the operator.
-If you have a local recovery program which recovers from a file, do this:
-
-
-mknod /tmp/tapepipe p
-rsh -n msdos dd if=/dev/ftape >> /tmp/tapepipe &
-localrecovery /tmp/tapepipe
-
-
-and delete /tmp/tapepipe when you're done.
-
-
-Notice that I'm using 'rsh' to the root user on the MS-DOS machine.
-This works with a correct .rhosts entry.
-The configuration on the 'tape144' disk allows rsh to root,
-but does not allow telnet or rlogin to root,
-logins are restricted to the console.
-This is good for security.
-
-
-If you are worried about a root .rhost file,
-you can create a new user on SAR#2, ``tapeuser'',
-with permissions to operate the tape drive but not the disks
-(create a new group and put tapeuser in that group,
-then chown and chmod the files /dev/rft* and
-/dev/nrft*).
-Your backup program then has to know to rsh to that username
-rather than to root.
-Of course, now there must be an .rhosts file in
-~tapeuser on SAR#2.
-For my own use, I have chosen this course, rather than a root .rhosts.
-
-
-Finally, the directions for a complete recovery to a trashed hard disk.
-This assumes that the Linux partition is completely unrecoverable.
-If necessary, reformat that partition as described in the Linux
-Installation HOWTO. Boot the Linux machine from SAR disk #1.
-When prompted, insert disk #2.
-Now, follow the directions in the file /root/notes
-(this was /tape144/root/notes when it was mounted on
-your Linux machine).
-Once both machines have been booted up, run the recovery routine you need.
-If you are running the backup scripts you can do it as follows:
-
-
-#change directory to the mount point of the hard disk partition
-which you will be recovering.
-#
-
-#if any mounted volumes are on the backup,
-and you want to recover them,
-create the mount points within the hard disk partition and
-mount the volumes.
-#
-
-#Enter the command:
-
-
-rsh -n msdos dd if=/dev/ftape | afio -i -v -Z -c 1024 -
-
-
-or
-
-
-rsh -n -l tapeuser msdos dd if=/dev/ftape | afio -i -v -Z -c 1024 -
-
-
-or
-
-
-mknod /tmp/backpipe p
-rsh -n msdos dd if=/dev/ftape >> /tmp/backpipe &
-afio -i -v -Z -c 1024 /tmp/backpipe
-
-
-
-#
-
-This reads the tape on the remote machine, writing the result to stdout,
-where afio picks it up.
-The '-i' switch tells it to recover the files relative to
-the current working directory (which is the root of the hard disk partition). '-v' is verbose, listing the files as they are recovered. '-Z' tells afio that this is an archive of individually compressed files. '-c 1024' tells it to use a 5 MB streaming buffer
-to avoid a lot of tape rewinding.
-----
-
-!!3. Notes
-
-
-The commands listed in the /tape144/root/notes file
-could be run from a script.
-When I tried, I got rpc setup errors.
-I suspect it was just that the commands were run too quickly,
-and the portmapper hadn't properly installed itself.
-I found that typing the sequence in manually worked fine,
-so I've recommended that.
-
-
-I think this setup is secure.
-Note that somebody can still get access to all your files
-if they go to the tape drive and pull the tape out before you get there,
-then then read the tape themselves.
-People with very sensitive data might consider encrypting the stream
-from the archiver.
-Archive to standard output and pipe the output to the encrypter,
-and redirect the output of the encrypter to append to the named pipe
-/tmp/tapepipe as described above. Note that errors in the
-recovery process will result in all files after that point being
-unrecoverable, as the entire archive is now a single DES-encrypted stream.
-It is possible to use options on afio to send each file
-in the archive first through gzip, then into an encryption program like
-des, but note that this compressing first
-does provide a fair amount of known plaintext
-for determined code breakers to work with, so a better approach might be
-to skip the gzip step and simply encrypt it with des, at the expense of
-significantly more tape area. Needless to say, DES encrypted files don't
-compress.
-
-
-The rc.inet1 directions I've included
-will allow only communication with the local network,
-not the rest of the world through a gateway.
-
-
-During a full recovery to a blank hard disk the SAR disk #3 provides
-ftape.o to the MS-DOS machine through NFS.
-This is because some old versions of the ftape module
-can't control some tape drives
-when there is a disk mounted in the floppy drive. With newer kernels, the
-entire NFS stuff can be omitted.
-
-
-__This is very important__.
-__***TEST***__ the SAR recovery procedure.
-I did, but don't leave anything to chance.
-Make sure that you can recover at least one file from your tape
-to the Linux machine using only the SAR disks
-(i.e. without mounting the hard disk).
-If you can't reboot the Linux machine without inconveniencing a lot of users,
-change the setup information on the SAR disks
-to assign the ``linux'' identity to another MS-DOS machine
-and then boot the two MS-DOS machines into Linux
-to make sure everything works.
-Then, change the ``linux'' identity back again
-so that you have usable SAR disks.
-----
-
-!!4. Copyright
-
-
-Copyright Jan 10, 1995 by Christopher Neufeld
-(
-neufeld@physics.utoronto.ca)
-
-
-Modified Feb 6, 1996.
-
-
-Modified Aug 5, 1997
.
-----
+Describe [HowToBackupWithMSDOS]
here.
