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--- other:win10wsl [2022/08/31 13:08]
jypeter [Creating a backup]
+++ other:win10wsl [2022/09/07 11:59]
jypeter [WSL security WARNING] Improved
@@ Line 174: / Line 174: @@
     * If you have an older Windows version (at least //Version 1903, Build 18362//), follow the [[https://docs.microsoft.com/en-us/windows/wsl/install-manual|Manual installation steps for older versions of WSL]]
-  * Open a ''Powershell'' in //administrator// mode
+  * Open a ''PowerShell'' in //administrator// mode
     * ''Start''=>''W''=>''Windows PowerShell'' then right-click on ''Windows PowerShell'' and select //Run as Administrator//
     * Use a [[https://wiki.lsce.ipsl.fr/pmip3/doku.php/other:win10apps#windows_terminal|Windows Terminal]], if you have already installed it. Use ''CTRL''+<left click> on ''Windows Powershell'' in the pull-down menu to get a ''Powershell'' in //administrator// mode
@@ Line 206: / Line 206: @@
   * Reboot the computer and be patient
     * This step will take some time (make sure you have 15-30 mn available). Windows will install and configure what it needs for running //WSL+Ubuntu//, reboot, and install some more //stuff//
-    * The final installation step will take place when you open your Windows session. A terminal opens, displaying the final installation of Ubuntu, and asking you for a username and password, and giving you access to a ''bash'' prompt
+    * The final installation step will take place when you open your Windows session. A terminal opens, displaying the final installation of Ubuntu, and asking you for a username and password, and giving you access to a ''bash'' prompt\\ <wrap hi>Do not use an existing password!</wrap> The security of the Linux running in WSL is weak by design, and somebody could easily extract your password information from a backup of your distribution
     * <code>Installing, this may take a few minutes...
 Please create a default UNIX user account. The username does not need to match your Windows username.
@@ Line 363: / Line 363: @@
 PS C:\> wsl cat /proc/version
 Linux version 5.10.102.1-microsoft-standard-WSL2 (oe-user@oe-host) (x86_64-msft-linux-gcc (GCC) 9.3.0, GNU ld (GNU Binutils) 2.34.0.20200220) #1 SMP Wed Mar 2 00:30:59 UTC 2022</code>
+  * Create a [[other:win10wsl#backup_of_a_full_linux_installation|backup of the newly installed distribution]]
+    * This will allow you to easily [[other:win10wsl#restoring_or_relocating_a_linux_installation|restore or relocate your distribution later]]
 ===== After the base installation =====
@@ Line 985: / Line 988: @@
 ===== Advanced usage =====
+==== WSL security WARNING! ====
+<WRAP center round important 60%>
+A regular Linux installation (on a Linux-only computer) is fairly secure,\\ but a Linux installation on WSL is not secure at all, **by design**
+</WRAP>
+WSL+Linux is designed to allow you to easily use Linux on Windows, including **very easily using the Linux root account without knowing any password** of the Linux installation!
+<code>PS C:\Users\your_login> wsl
+wsl_default_user@your_machine:/mnt/c/Users/your_login$ whoami
+wsl_default_user
+PS C:\Users\your_login> wsl -u root
+root@your_machine:/mnt/c/Users/your_login# whoami
+root</code>
+This is **a feature and not a security issue**, because your installation is protected by your Windows account security
+You should be aware (and act accordingly) that:
+  * Somebody gaining access to your Windows account will also have full access to the Linux installation
+    * <wrap hi>Do not use an existing password for the WSL Linux account</wrap>
+    * Storing data in the Linux part of your computer does not add any extra security
+    * Always **make sure that only you can access your Windows account**
+    * Your LSCE Windows laptop (not your desktop) is encrypted with [[https://docs.microsoft.com/en-us/windows/security/information-protection/Bitlocker/bitlocker-overview|BitLocker]], which adds some extra security
+  * Somebody gaining access to a backup of your Linux installation will easily have access to the Linux installation itself
+    * You can store your Linux installation backup to [[https://docs.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-to-go-faq|an external disk encrypted with BitLocker]]
 ==== Creating a backup ====
@@ Line 1011: / Line 1040: @@
     * If you are not going to use the backup tar file right away, you can optionally compress it in order to save some space
-      * <code>Add compression example here</code>
+      * <code>$ ls -lh /mnt/c/Scratch/<your_login>/WSL/WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar
+.4G Aug 29 17:49 /mnt/c/Scratch/<your_login>/WSL/WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar
+$ gzip  /mnt/c/Scratch/<your_login>/WSL/WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar
+$ ls -lh /mnt/c/Scratch/<your_login>/WSL/WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar.gz
+M Aug 29 17:49 /mnt/c/Scratch/<your_login>/WSL/WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar.gz</code>
 === Backup of specific directories ===
@@ Line 1039: / Line 1074: @@
 ==== Restoring or relocating a Linux installation ====
-When we have a backup in a tar file, we can restore it to the default location (Check ?? FIXME), or specify where we want to restore it. This is a way of moving (relocating) an installation to another disk or partition than the default location ''C:\''
+When we have the tar file of a [[other:win10wsl#creating_a_backup|FULL backup]], we can use [[https://docs.microsoft.com/en-us/windows/wsl/basic-commands#import-a-new-distribution|--import]] to install or restore it to a specific location.
+Note:
+  * This is currently the only way of **moving (//relocating//) a Linux installation** to another disk than the default ''C:\'' location
+  * //Importing// will mostly put the ''ext4.vhdx'' file in the specified target location
+    * You need [[other:win10wsl#disk_usage|enough disk space]] in the new disk location, knowing that the size of the ''vhdx'' file will start growing (as needed) as soon as you use your installation
+  * Creating a backup and restoring it is an indirect way of **reclaiming the unused space of a Linux installation**: the size of the ''ext4.vhdx'' file after importing can be smaller than the size of the originally exported ''ext4.vhdx'' file.
+Detailed [[https://docs.microsoft.com/en-us/windows/wsl/basic-commands#import-a-new-distribution|--import]] example:
+  * We assume that we have an exported installation tar file available
+    * In this example, we use the compressed backup file created in [[other:win10wsl#backup_of_a_full_linux_installation|Backup of a FULL Linux installation]]\\ ''C:\Scratch\<your_login>\WSL\WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar.gz''
+    * ''import'' can directly use a ''.tar.gz'' file! ([[https://github.com/MicrosoftDocs/WSL/issues/1607|wsl --import should mention 'tar.gz' support !]])
+  * Create the directory where the Linux installation (mostly its ''ext4.vhdx'' file) will be restored
+    * Hint: use an explicit directory path and name using the name of the distribution that will be restored, because the name of the restored file itself will always be the same (''ext4.vhdx'')\\ e.g. ''D:\WSL_Distributions\Ubuntu_custom''
+  * Import the distribution, giving it a unique name (that does not appear already in ''wsl -l -v'')
+    * <code>> wsl -l -v
+  NAME      STATE           VERSION
+* Ubuntu    Stopped         2
+> wsl --import Ubuntu_custom D:\WSL_Distributions\Ubuntu_custom C:\Scratch\<your_login>\WSL\WSL_Ubuntu_20.04.5_LTS_stdu_22-08-29.tar.gz
+> wsl -l -v
+  NAME             STATE           VERSION
+* Ubuntu           Stopped         2
+  Ubuntu_custom    Stopped         2</code>
+    * After importing, there should be a new ''ext4.vhdx'' file in the previously empty ''D:\WSL_Distributions\Ubuntu_custom'' directory
+  * Start the imported ''Ubuntu_custom'' distribution
+    * Directly from the Windows Terminal pull-down menu
+    * Or from a PowerShell, using ''wsl --distribution Ubuntu_custom''
+    * WARNING: even if the distribution we imported had an existing default ''stdu'' user, the //new// default user will be ''root'' !
+      * It is possible to explicitly specify the requested user each time we start a terminal, but it will be more convenient to specify a default user\\ ''%%wsl --distribution Ubuntu_custom --user stdu%%''
+      * You can easily open a ''root'' session with\\ ''%%wsl -d Ubuntu_custom -u root%%''
+  * Specify a default user (note: [[https://docs.microsoft.com/en-us/windows/wsl/use-custom-distro#add-wsl-specific-components-like-a-default-user|Add WSL a default user]] also shows how to //create a new user//). We just have to use the root account to add a default user (user ''stdu'' in this example) to the [[https://docs.microsoft.com/en-us/windows/wsl/wsl-config#user-settings|/etc/wsl.conf]] file
+    * <code># cat /etc/wsl.conf
+cat: /etc/wsl.conf: No such file or directory
+# echo -e "[user]\ndefault=stdu" >> /etc/wsl.conf
+# cat /etc/wsl.conf
+[user]
+default=stdu</code>
+    * Restart the Linux installation to take the new settings into account
+      * ''%%wsl  --terminate Ubuntu_custom%%''
+    * If you need the ''root'' account later, you will need to use the ''sudo'' command from the new default account
+      * <code>$ whoami
+stdu
+stdu@sadira034:~$ sudo su -
+[sudo] password for stdu:
+root@sadira034:~# whoami
+root</code>
 FIXME Read [[https://www.howtogeek.com/426562/how-to-export-and-import-your-linux-systems-on-windows-10/|How to Export and Import Your Linux Systems on Windows 10]] and [[https://winaero.com/blog/export-import-wsl-linux-distro-windows-10/|Export and Import WSL Linux Distro in Windows 10]] and similar threads
@@ Line 1145: / Line 1229: @@
   * [[https://docs.microsoft.com/en-us/windows/wsl/release-notes|Release Notes for Windows Subsystem for Linux]]
+  * [[https://craigloewen-msft.github.io/WSLTipsAndTricks/|WSL Tips and Tricks]]
   * [[https://docs.microsoft.com/en-us/windows/wsl/faq|Frequently Asked Questions]]
   * [[https://docs.microsoft.com/en-us/windows/wsl/troubleshooting|Troubleshooting]]

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