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# Network booting
without GRUB
https://www.youtube.com/watch?v=U3RC20ANomk
`apt install dnsmasq`
`/etc/dnsmasq.conf`
```
interface=<your interface>,lo
bind-interfaces
dhcp-range=<your interface>,192.168.11.101,192.168.11.200
dhcp-boot=pxelinux.0
dhcp-match=set:efi-x86_64,option:client-arch,7
dhcp-boot=tag:efi-x86_64,syslinux.efi
enable-tftp
tftp-root=/srv/tftp
```
`mkdir -p /srv/tftp`
`apt install syslinux-common syslinux-efi`
`cd /usr/lib/syslinux/modules/efi64`
`cp ldlinux.e64 libutil.c32 menu.c32 /srv/tftp`
`cp /usr/lib/SYSLINUX.EFI/efi64/syslinux.efi /srv/tftp`
`mkdir /srv/tftp/pxelinux.cfg`
`/srv/tftp/pxelinux.cfg/default`
```
UI menu.c32
LABEL FIKS OS
MENU LABEL FIKS
KERNEL vmlinuz
APPEND initrd=initrd.img debug components boot=nfs ip=dhcp root=/dev/nfs nfsroot=192.168.11.11:/srv/nfs/live/ ro
TEXT HELP
Lmao Yeet!
ENDTEXT
```
`systemctl restart dnsmasq.service`
`apt install nfs-kernel-server`
`mkdir -p /srv/nfs/live`
`/etc/exports`
```
/srv/nfs *(ro,sync,no_root_squash,no_subtree_check)
```
`exportfs -a`
`systemctl restart nfs-kernel-server`
## Client system
### Image itself
Disable systemd-resolved (requires writable /etc/resolve.conf):
`systemctl mask systemd-resolved.service`
`systemctl mask systemd-hostnamed.service`
`systemctl mask systemd-timesyncd.service`
`systemctl mask systemd-update-utmp.service`
`systemctl mask systemd-update-utmp-runlevel.service`
`systemctl mask ModemManager.service`
`systemctl mask man-db.service`
`systemctl mask logrotate.service`
`systemctl mask grub-initrd-fallback.service`
`systemctl mask grub-common.service`
`systemctl mask snapd`
`systemctl enable tmp.mount`
### Initrd
`mkdir initrd-workdir && cd initrd-workdir`
`unmkinitramfs /boot/initrd.img-$(uname -r) .`
`cd main`
`/etc/initramfs-tools/modules`
```
e1000
igb
r8169
nfs
nfsv3
nfsv4
sunrpc
lockd
fscache
overlay
```
https://www.onlogic.com/blog/how-to-build-a-read-only-linux-system/
`/etc/initramfs-tools/hooks/ro_root`
```bash
#!/bin/sh
PREREQ=''
prereqs() {
echo "$PREREQ"
}
case $1 in
prereqs)
prereqs
exit 0
;;
esac
. /usr/share/initramfs-tools/hook-functions
manual_add_modules aufs
manual_add_modules tmpfs
copy_exec /bin/chmod /bin
```
`/etc/initramfs-tools/scripts/init-bottom/ro_root`
```bash
#!/bin/sh
PREREQ=''
prereqs() {
echo "$PREREQ"
}
case $1 in
prereqs)
prereqs
exit 0
;;
esac
ro_mount_point="${rootmnt%/}.ro"
rw_mount_point="${rootmnt%/}.rw"
# Create mount points for the read-only and read/write layers:
mkdir "${ro_mount_point}" "${rw_mount_point}"
# Move the already-mounted root filesystem to the ro mount point:
mount --move "${rootmnt}" "${ro_mount_point}"
# Mount the read/write filesystem:
mount -t tmpfs root.rw "${rw_mount_point}"
# Mount the union:
mount -t aufs -o "dirs=${rw_mount_point}=rw:${ro_mount_point}=ro" root.union "${rootmnt}"
# Correct the permissions of /:
chmod 755 "${rootmnt}"
# Make sure the individual ro and rw mounts are accessible from within the root
# once the union is assumed as /. This makes it possible to access the
# component filesystems individually.
mkdir "${rootmnt}/ro" "${rootmnt}/rw"
mount --bind "${ro_mount_point}" "${rootmnt}/ro"
mount --bind "${rw_mount_point}" "${rootmnt}/rw"
```
`update-initramfs -u`
`scp initrd.img server@192.168.11.11:/srv/nfs/`
`mksquashfs / /opt/fiks-image.squashfs -e /proc /sys /dev /tmp /run /mnt /media /var/cache /var/tmp /opt`
## Back on the server
`mount -o loop /srv/nfs/fiks-image.squashfs /srv/nfs/tmp/`
`cp -a /srv/nfs/tmp/* /srv/nfs/live/`
`mkdir -p live/{dev,proc,run,sys,tmp}`
`mkdir -p live/var/tmp`
`etc/fstab`
```
192.168.11.11:/srv/nfs/live / nfs nolock,ro 0 0
tmpfs /var/tmp tmpfs defaults,nosuid,nodev,mode=1777,size=64M 0 1
```