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Configuring Linux as a dual-purpose user environment.
Creation of Floppy Disks for Remote Bootstrapping

A two-step procedure was used to generate remote bootstrap floppy disks for client machines. First, the kernel source residing on the server was recompiled to include “root file system on NFS (Network File System)” support. Once compilation was complete, the newly created kernel image was moved from /usr/src/linux/arch/i386/boot/zImage to /tftpboot/adm/client_boot_image_remote. A new disk was labeled and inserted in the server's floppy drive. A dummy device, /dev/boot22, was created with the mknod utility. The dd utility was used to copy client_boot_image_remote to the floppy disk. The rdev utility was then used to set the root device for the kernel residing on the floppy image to the dummy device /dev/boot22. The following sequence of commands was used to create the remote bootstrap floppy disk:

mknod /dev/boot255 c 0 255
dd if=/adm/client_boot_image_remote/zImage of=/dev/fd0
rdev /dev/fd0 /dev/boot255

Finally, this procedure was captured in a shell script and used to create additional remote bootstrap floppy disks.

Local Client Configuration

All client systems included a hard disk configured to provide a single 50MB swap partition, /dev/sda1. This would allow experimental users to partition the remainder of the drive to suit their needs when installing Linux on their systems. Because the only CD-ROM resides on lin2, any installation of Linux to a client system other than lin2 has to be done via NFS. To make such an installation possible, modifications to the MCA Slackware 3.1 boot floppy were necessary. The boot floppy was mounted under the /mnt directory using the command

mount -t minix /dev/fd0 /mnt

The file /mnt/etc/networks was updated, changing LOCALNET to IP address 151.141.99.0. The MCA Slackware 3.1 boot floppy assumes that if a network installation is being conducted, the network is of type Ethernet. Therefore, it was necessary to edit the file /mnt/usr/lib/set/INSNFS, changing all occurrences of eth0 to tr0. As with the remote bootstrap floppy, a script was written to automate the above operations.

Conclusion

The declining cost of disk drives, together with concerns about system security, have made diskless workstation operation and remote protocols like RARP less attractive. “Relatively inexpensive”, however, is still not quite “free”. We described a strategy for implementing a Linux-based laboratory that, in effect, uses diskless operation to support regular as well as standard users, at no additional cost.

ETSU's Linux-based computer lab has not been fully integrated into the ETSU curriculum, due primarily to unforeseen delays including equipment outages caused by a thunderstorm. The lab, however, is operational. Two students used the lab in spring 1998 to develop a serial line driver for a senior-level operating systems course. Currently, plans are being made to use the laboratory as a tool for teaching graduate operating systems and undergraduate networking courses in the coming academic year.

Scott Gray (sgray@eolian.com) is the Senior System Designer for Eolian Inc. (www.eolian.com), where he is currently working on Internet caching proxy server development. Scott is also completing a master's thesis at East Tennessee State University on disk caching and adaptive block rearrangement. He and his cat, Sheba, regularly commute between their home in Church Hill, Tennessee and Eolian's office in Fairfax, Virginia.

Luke Pargiter is currently the Network Operations Supervisor at Pilot Corporation, a $2 billion privately owned petroleum retailer and travel center operator. He was formerly the Systems Manager for the Dept. of Computer and Information Sciences at East Tennessee State University. In his spare time, he reads, plays golf and guitar, and takes long walks with his wife, Rose. Luke can be reached via e-mail at pargitel@pilotcorp.com.

Phil Pfeiffer, assistant professor of computer and information science, currently teaches at East Tennessee State University (www.etsu-cs.edu). Phil, who earned his Ph.D. in computer science from UW-Madison in 1991, is currently working on his cave diving certifications. He has also done systems programming for PPG Industries (1977-1984) and taught computer science at East Stroudsburg University (1991-1996).

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