install arch finish

content/post/install-arch-linux-in-virtual-machine.md

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+
+Installing Arch Linux on a KVM/QEMU virtual macin eis a fairly startightforward process. We will use command line approach in this post.
+
+## Create a virtual machine
+Here we use `virt-install` to create a virtual machine. Run the following as root:
+```bash
+virt-install -n arch \
+--os-type=linux \
+--os-variant=archlinux \
+--ram=2048 \
+--vcpus=4 \
+--disk path=/var/lib/libvirt/images/arch.qcow2,bus=virtio,size=32 \
+--graphics=spice \
+--cdrom /path/to/image.iso \
+--network default
+```
+
+### What is happening here?
+- Here we specify name for the virtual machine, which is *arch*.
+- Next we specify type and variant.
+- The amount of RAM is specified in megabytes.
+- We assign four virtual CPUs to the VM.
+- In `disk path` we have given the default location where the virtual machine image is stored.
+- Size is in gigabyes.
+- We have used *spice* for graphics. Alternatively, VNC can be used.
+- In `cdrom` we have provided the location of the boot media.
+- Finally we asked `virt-install` to use the default network profile.
+
+Pressing Enter will start the creation of the virtual machine. When done, it will start *virt-viewer* with live media running.
+
+## Install Arch Linux
+This part is the same as any Arch Linux installation. We partition disks, run bootstrap script, generate locales, set timezone, hostname, install bootloader and optionally a desktop environment.
+
+### Partition disks
+The virtual storage goes by `/dev/sda`. We partition disks using `cfdisk`. Select **dos** partition tabke since we are not using UEFI. Create just one partition and use it as root. Write then quit the program.
+
+Now we format the partition.
+```bash
+mkfs.ext4 /dev/vda1
+```
+
+### Mount root partition and install
+Now we are ready to install Arch Linux. Mount root partition on `/mnt` with `mount /dev/vda1 /mnt`. Then we run the bootstrap script that will create the necessary files and install the specified packages.
+```bash
+pacstrap /mnt base base-devel linux vim dhcpcd
+```
+
+#### What is happening here?
+- Here we asked `pacstrap` to install Arch Linux on `/mnt`.
+- Then we specified the packages to be installed.
+- The meta package `base` contains a minimal package set that defines a basic Arch Linux installation. It includes basic utilities like glibc, bash, coreutils, networking tools, systemd, etc. 
+- Next is the `base-devel` group. It contains tools to build many packages like gcc, make, binutils, etc.
+- `linux` is the kernel.
+- We require `vim` to configure various things. Any text editor will do.
+- `dhcpcd` will allow us to connect to the internet. Alternatively, `networkmanager` can be used.
+
+### Generate fstab
+This file tells which partitions to mount during boot. Instead of writing by hand, we use a tool to simplify things for us. Running the following
+```bash
+genfstab -U /mnt >> /mnt/etc/fstab
+```
+will generate a fstab file. We asked it to use `/mnt` partition. Any partition under `/mnt` will also be included, so if you created separate `/home` and `/var` partitions, they will also be included. The `-U` parameter tells `genfstab` to use UUID.
+
+## Configuration
+In this section we set timezones, locale and hostname.
+
+Chroot into new root
+```bash
+arch-chroot /mnt
+```
+
+### Set timezone
+List timezones by running `timedatectl list-timezones`. Set timezone with
+```bash
+timedatectl set-timezone Asia/Kolkata
+```
+Replace **Asia/Kolkata** with your timezone.
+
+### Set locale
+Uncomment the desired locales in `locale.gen`
+```bash
+vim /etc/locale.gen
+```
+Save and exit then generate them by running
+```bash
+locale-gen
+```
+And set locale config
+```bash
+echo LANG=en_US.UTF-8 > /etc/locale.conf
+export LANG=en_US.UTF-8
+```
+Replace **en_US.UTF-8** with your locale.
+
+### Configure network
+#### Set hostname
+Your virtual machine will be identified by this name on the network
+```bash
+echo arch-vm > /etc/hostname
+```
+
+#### Create /etc/hosts
+Your computer will look here for resolving domain names before looking out on the internet. Put the following information in `/etc/hosts`:
+```bash
+127.0.0.1   localhost
+::1         localhost
+127.0.1.1   arch-vm
+```
+
+#### Enable dhcpcd
+This will enable the virtual machine to connect to the internet
+```bash
+systemctl enable dhcpcd.service
+```
+
+### Create a user
+Before we create a regular user, it becomes necessary to set a root password. Set it by running 
+```bash
+passwd 
+```
+Create a new user with
+```bash
+useradd -m -G wheel,storage,power -s /bin/bash <username>
+```
+
+#### What is happening here?
+- `-m` tells `useradd` ro create a home directory for this user.
+- `-G` tells which groups this user will belong to.
+- `-s` specifies the login shell for this user.
+- Replace &lt;username&gt; with a username of your choice.
+
+Set a password for this user with
+```bash
+passwd <username>
+```
+
+### Install ssh server
+If working on command line is all you have to do, then working via SSH is more convenient than using Spice client (or VNC if you chose that). Install it 
+```bash
+pacman -S openssh
+```
+and enable it 
+```bash
+systemctl enable sshd.service
+```
+
+### Install bootloader
+The instructions thus far will provide us a working bare minimum Arch Linux environment. Now it is time to install a bootloadet and finish the installation. We will go with grub.
+```bash
+pacman -S grub
+grub-install /dev/vda
+grub-mkconfig -p /boot/grub/grub.cfg
+```
+#### What is happening here?
+- First we install grub package.
+- Then we install it on the device `/dev/vda`.
+- Next we create a configuration file. It can be modified at `/etc/default/grub`. Every time we modify the configuration, it must be generated with the last command for the changes to take place.
+
+### Reboot
+The installation is complete. Next time we boot, we will be dropped into a working Ach Linux environment. 
+
+Exit chroot.
+```bash
+exit
+```
+Unmount partition
+```bash
+umoount /mnt 
+```
+And reboot 
+```bash
+reboot
+```
+
+## Connecting to the virtual machine
+Wait for a minute and the virtual machine will be up. FInd the virtual machine's IP address on host machine (assuming **arch** is the name of your virtual machine)
+```bash
+virsh domifaddr arch
+```
+
+Save the IP address in your host's `/etc/hosts`
+```bash
+printf "<ip-address>\t<guest hostname>\n" | sudo tee -a /etc/hosts
+```
+Replace `<ip-address>` with the IP address of the virtual machine and `<guest hostname>` with the hostname you set while installing the virtual machine. It wuold be something like
+```bash
+printf "192.168.122.43\tarch-vm\n" | sudo tee -a /etc/hosts
+```
+
+### Create SSH key pair
+While not necessary on a local network, it is generally a good habit to use key pair instead of password authentication.
+
+Go to `~/.ssh` and create a key pair.
+```bash
+cd ~/.ssh 
+ssh-keygen -t ed25519 -f arch-vm -C "arch linux virtual machine"
+```
+
+#### What is happening here?
+- `ssh-keygen` generates keys. 
+- `-t` specifies the type of the key. We chose Ed25519. Other popular types are EdDSA, RSA, DSA, etc.
+- `-f` specifies the filename of this key pair. 
+- `-C` is used to put comment in the key.
+
+This process will ask for a passphrase and generates a private key and a public key. The public key will have extension `.pub`. 
+
+Create a config file. This will tell SSH which key to use with respect to host. The file is named `config`. Put the following in the file
+```
+Host arch-vm
+  IdentityFile ~/.ssh/arch-vm
+```
+
+The private key is used to identify you. Anybody with your private key will be impersonate you so keep it safe.
+
+Now copy the public key over to your virtual machine. It can be achieved by programs like `scp` or `rsync`. However, we will use `ssh-copy-id` to conveniently put our key while abstracting most parts. 
+```bash
+ssh-copy-id -f -i ~/.ssh/arch arch@arch-vm
+```
+It is assuming **arch** is the username of the normal user of the virtual machine. 
+
+Now log in by running
+```bash
+ssh arch@arch-vm
+```
+
+Modify `/etc/ssh/sshd_config` to only use public key for authentication. 
+- Change `PubkeyAuthentication` to `yes`
+- Change `PasswordAuthentication` to `no`
+- Change `X11Forwarding` to `yes`
+
+Now restart `sshd` for changes to take place.
+```bash
+systemctl restart sshd.config
+```
+Exit and try logging in again. This time it should ask for passphrase.
+
+## Install a desktop environment
+This part is entirely optional if you wish to use GUI. In this post, we will install  MATE desktop environment. 
+```bash
+pacman -S mate mate-extra
+```
+The desktop environment can be started by running `exec mate-session`. If you want to use xinit then put the command in `~/.xinitrc`. Then install `xorg-xinit` package. Start it with `startx`.
+
+ Alternatively you can use a display manager like GDM, LightDM, SDDM. etc. Install `sddm`, enable and start it 
+ ```bash
+ systemctl enable sddm.service
+ systemctl start sddm.service
+ ```
+
+ If you wish to run GUI programs over X11 forwarding, a desktop environment might be overkill. In that case just install `xorg`, `xorg-server`. To use X11 forwarding, log in via ssh with
+ ```bash
+ ssh -Y arch@arch-vm
+ ```