unattended install of ubuntu server
Video reference
https://www.youtube.com/watch?v=DtXZ6BMaKbA
https://files.catbox.moe/fztpyo.mp4

-  Download iso from here:  https://cdimage.ubuntu.com/releases/18.04.6/release/
-  Copy autoinstall-user-data file from `/var/log/installer` from where ubuntu-live-server-23.... .iso is installed. Then create a directory say 'server_work'. Under it create a autoinstall-user-data and copy necessary things like
    ```
	#cloud-config
	autoinstall:
	  identity:
		hostname: tree
		password: $6$oylcLD1tDk6UPHJf$xSwvFGR8314IlJBENXKKqAGbcHWuzPp7le3HRAzaSPg7I2vJk.pFEnMICyPOQwjJGjaPqejSEkPcyaG9T7kRW.
		realname: tree
		username: tree
	  kernel:
		package: linux-generic
	  keyboard:
		layout: us
		toggle: null
		variant: ''
	  locale: en_US.UTF-8
	  ssh:
		allow-pw: true
		authorized-keys: []
		install-server: true
	  updates: security
	  version: 1
	  shutdown: poweroff

	```
- Now create directory 'source-files' and use this 
   `xorriso -osirrox on -indev ubuntu-23.10-live-server-amd64.iso --extract_boot_images source-files/bootpart -extract / source-files/
`
- Now go to source-files dir and create dir nocloud and go to nocloud and use
  `cp ../../autoinstall-user-data user-data`. Now create file named meta-data. Finally go to parent dir ie source-files. 
- Now go to boot/grub and add write permission for root for file grub.cfg using `chmod 644 grub.cfg`
-  Open  grub.cfg. Create menuentry for automatic install like this
   After the line `set menu_color_highlight=black/light-gray` add this
	  ```
	  menuentry "Autoinstall Ubuntu Server" {
			set gfxpayload=keep
			linux /casper/vmlinuz quiet autoinstall ds=nocloud\;s=/cdrom/nocloud/ ---
			initrd /casper/initrd
	}

	  ```
   and set timeout=5 instead of 30
 -  Go to source files directory. Now use this 
   `xorriso -as mkisofs -r -V "ubuntu-autoinstall" -J -boot-load-size 4 -boot-info-table -input-charset utf-8 -eltorito-alt-boot -b bootpart/eltorito_img1_bios.img -no-emul-boot -o ../installer.iso .`


- ssh
  `sudo nano /etc/ssh/sshd_config` 
  Change port if desired
  
  `ssh username@ip_address -p 22`  . here ip_address can be local or public. 22 is default port
  When port forwarding externally, using pyblic ip address make sure to have some firewall like `fail2ban` or `ufw`
  In order to use GUI locally when opening through ssh. 
  for eg: opening gui in A if remote machine is B.
  `ssh -X userB@ip_address -p $DEFAULT_PORT`