7.3. Construction

7.3.1. Verify presence of getty and login

bash# ls ~/staging/sbin/getty bash# ls ~/staging/bin/login

7.3.2. Modify inittab for multi-user mode

Modify ~/staging/etc/inittab by changing the default runlevel and adding getty entries as shown below.

# /etc/inittab - init daemon configuration file # # Default runlevel id:2:initdefault: # # System initialization si:S:sysinit:/etc/init.d/rc S # # Runlevel scripts r0:0:wait:/etc/init.d/rc 0 r1:1:respawn:/bin/sh r2:2:wait:/etc/init.d/rc 2 r3:3:wait:/etc/init.d/rc 3 r4:4:wait:/etc/init.d/rc 4 r5:5:wait:/etc/init.d/rc 5 r6:6:wait:/etc/init.d/rc 6 # # Spawn virtual terminals 1:235:respawn:/sbin/getty 9600 tty1 linux 2:235:respawn:/sbin/getty 9600 tty2 linux 3:235:respawn:/sbin/getty 9600 tty3 linux 4:235:respawn:/sbin/getty 9600 tty4 linux 5:235:respawn:/sbin/getty 9600 tty5 linux 6:2345:respawn:/sbin/getty 9600 tty6 linux # # end of /etc/inittab

7.3.3. Create tty devices

bash# cd ~/staging/dev bash# mknod tty0 c 4 0 bash# mknod tty1 c 4 1 bash# mknod tty2 c 4 2 bash# mknod tty3 c 4 3 bash# mknod tty4 c 4 4 bash# mknod tty5 c 4 5 bash# mknod tty6 c 4 6 bash# mknod tty c 5 0

7.3.4. Create support files in /etc

7.3.4.1. /etc/issue

Create the file ~/staging/etc/issue using the example below or design a customized message.

Connected to \l at \b bps.

Be sure that "\l" is a lowercase letter L and not the number one.

7.3.4.2. /etc/passwd

Use a text editor to create a minimal passwd file conforming to the Linux Standards Base (LSB) document. Save the file as ~/staging/etc/passwd

root::0:0:Super User:/root:/bin/sh bin:x:1:1:Legacy UID:/bin:/bin/false daemon:x:2:2:Legacy UID:/sbin:/bin/false

7.3.4.3. /etc/group

Use a text editor to create an LSB conforming group file and save it as ~/staging/etc/group

root::0:root bin:x:1:root,bin,daemon daemon:x:2:root,bin,daemon

7.3.4.4. /etc/nsswitch.conf

Create the following file and save it as ~/staging/etc/nsswitch.conf

passwd: files group: files

7.3.5. Copy required libraries

bash# cp /lib/libnss_files.so.2 ~/staging/lib

7.3.6. Set directory and file permissions

Set minimal privileges on all files and directories under ~/staging. Everything is owned by the root user and the root group. Permissions are read-write for the owner and read-only for the group. Exceptions to the blanket permissions are handled case-by-case.

bash# cd ~/staging bash# chown -R 0:0 * bash# chmod -R 640 *

Set execute permission on all directories. (Note the capital "X")

bash# chmod -R +X *

Files in /bin are read and execute for all, but su is an exception.

bash# chmod 755 bin/* bash# chmod 4750 bin/su

Files in /dev have various permissions. Disk devices should be accessible to administrators only. Other files like /dev/null should have full privileges granted to everyone.

bash# chmod 660 dev/fd0 dev/ram0 bash# chmod 666 dev/null bash# chmod 622 dev/console bash# chmod 600 dev/initctl bash# chmod 622 dev/tty bash# chmod 622 dev/tty?

The passwd and group files must be world readable.

bash# chmod 644 etc/passwd bash# chmod 644 etc/group

The scripts in /etc/init.d are read and execute for administrators.

bash# chmod 750 etc/init.d/*

Libraries need read and execute permissions for everyone.

bash# chmod 755 lib/*

Only root should have access to the /root directory.

bash# chmod 700 root

Make files in /sbin read and execute for administrators.

bash# chmod 750 sbin/*

Temp should be read-write for all with the sticky bit set.

bash# chmod 1777 tmp

7.3.7. Create the root disk image

bash# cd / bash# dd if=/dev/zero of=/dev/ram7 bs=1k count=4096 bash# mke2fs -m0 /dev/ram7 bash# mount /dev/ram7 /mnt bash# cp -dpR ~/staging/* /mnt bash# umount /dev/ram7 bash# dd if=/dev/ram7 of=~/phase6-image bs=1k bash# gzip -9 ~/phase6-image

7.3.8. Copy the image to diskette

Insert the diskette labled "root disk" into drive fd0.

bash# dd if=~/phase6-image.gz of=/dev/fd0 bs=1k