Week 2 Learning Journal

SSH and File System Mount Information

SSH

• SSH Layers:
  • SSH operates on three layers:
    1. Transport layer
    2. Authentication layer
    3. Communication layer
• CLI Usage:
  • SSH is commonly used via the command-line interface (CLI) for secure remote access to servers.
• Key-Based Authentication:
  • SSH authentication often involves the use of key pairs, consisting of a private key and a corresponding public key.
• Sudo User and Package Management:
  • In Linux, the sudo command is used to execute commands with superuser privileges.
  • Package management commands like dnf, yum, and apt are often used with sudo to install, remove, or update software packages.

Docker, Vagrant, and Containers

• Learning About:
  • Docker and Vagrant are tools used for containerization and virtualization, respectively.
  • Containers provide a lightweight and portable way to package and deploy applications.

Chapter 2: Displaying File System Mount Information

• Command Usage:
  • Various commands can be used to display information about file system mounts and storage devices.
• Commands:
  1. man mount: Displays the manual page for the mount command, providing detailed information on its usage and options.
  2. mount | grep nvme: Filters mount information to display only entries related to NVMe devices.
  3. blkid: Prints block device attributes like UUID and file system type.
  4. lsblk: Lists information about block devices and their relationships.
  5. df: Displays disk space usage of file systems.
  6. df -h: Displays disk space usage in a human-readable format.
  7. vim /etc/mtab: Opens the mount table file /etc/mtab for editing using the Vim text editor.

Day 2: Linux Filesystems

Commands and Tools

• mount Command:
  • Used to mount filesystems and displays information about mounted filesystems.
  • Use man mount to access the manual page for detailed information on the mount command.
• /etc/mtab File:
  • Stores information about currently mounted filesystems.
  • Use mount | grep nvme or cat /etc/mtab | grep nvme to filter and display information about NVMe devices.
• /proc/mounts:
  • Another file used to show information about mounted filesystems.
• blkid Command:
  • Prints block device attributes like UUID and filesystem type.
• lsblk Command:
  • Lists information about block devices, their partitions, and other details.
  • Use lsblk -f to display additional information.
• fuser Command:
  • Identifies processes using a specified file or filesystem.
  • Use fuser /mnt/backup or fuser -v /mnt/backup to check processes using a specific directory.
• lsof Command:
  • Lists open files and the processes that opened them.
  • Use lsof | head to display the first few lines of output or lsof | grep /mnt/backup to filter output for processes related to a specific directory.
• mount -a Command:
  • Mounts all filesystems listed in /etc/fstab.
• df -h Command:
  • Displays disk space usage in a human-readable format.
• Editing /etc/mtab:
  • Use vim /etc/mtab to open the /etc/mtab file for editing using the Vim text editor.

Day 3: Chapter 2 - Videos 2 to 6

Video 2

• Manually Mounting Filesystems:
  • Use umount /mnt/data to unmount a filesystem.
  • Use fuser and lsof commands to identify processes preventing a filesystem from being unmounted.
  • fuser -v provides more detailed information.
  • lsof | head and lsof | grep /mnt/backup are used to list open files related to a specific directory.
  • Use fuser -k mnt/backup to kill processes using a filesystem.

Video 3

• Automatic Mounting at Boot:
  • When the system boots, it doesn’t automatically add entries into fstab, so drives are not auto-mounted.
  • Use mount -a command to read fstab and mount filesystems listed there.
  • Use lsblk -l to list block devices.
• sync Command:
  • sync flushes filesystem buffers.

Video 4

• Swap Space:
  • Swap space is used as virtual memory when physical RAM is full.
  • Typically, swap space is twice the amount of RAM.
  • Use commands like swapon -s, swapon --show, or cat /proc/swaps to view swap usage.
  • free command displays memory usage.
• Systemd Mount Units:
  • Systemd automatically creates mount units based on fstab information.
  • Explore systemd mount units in /run/systemd/generator.

Video 6 (Lab 1 of Chapter 2)

Learning Objectives:

1. Create and enable a swap partition using /dev/xvdg1.
2. Add an entry to /etc/fstab to ensure the swap partition persists through a reboot (use the UUID).
3. Create and enable a 1 GB swap file in the root directory called “extraswap”.
4. Add an entry to /etc/fstab to ensure the swap file persists through a reboot (use the full path to the file name).

Lab: Working with Swap Space

Task 1: Creating and Enabling a Swap Partition

• Designating Swap Disk:
  • Used lsblk command to identify the swap disk.
  • Created swap space using mkswap /dev/xvdg1.
  • Enabled swap space using sudo swapon /dev/xvdg1.
  • Verified swap space using swapon --show.
• Adding Entry to /etc/fstab:
  • Edited /etc/fstab using vim /etc/fstab.
  • Added the UUID entry for swap partition and saved the file.

Task 2: Creating and Enabling a Swap File

• Creating Swap File:
  • Created a 1 GB swap file using dd if=/dev/zero of=/extraswap bs=1M count=1024.
  • Checked file size using ll -h /extraswap.
  • Restricted read access for others and granted only root write access using chmod 600 /extraswap.
  • Designated the file as swap using mkswap /extraswap.
  • Enabled the swap file using swapon /extraswap.
  • Verified the swap file using swapon --show.
• Adding Entry to /etc/fstab:
  • Added the swap file entry to /etc/fstab to ensure persistence through reboot.

Lab: Working with Systemd Mount Units

Task 1: Creating a Unit File for Data Mount

• Creating Unit File:
  • Used lsblk -f to grab UUID for the data mount.
  • Created a unit file mnt-data.mount in /etc/systemd/system with appropriate configuration.
  • Reloaded systemd using systemctl daemon-reload.
  • Enabled and started the mount unit using systemctl enable mnt-data.mount --now.

Task 2: Creating a Unit File for Backup Mount

• Creating Unit File:
  • Similar steps as Task 1 for creating a unit file mnt-backup.mount.

Task 3: Creating an Automount Unit File for Backup Mount

• Creating Automount Unit File:
  • Created an automount unit file mnt-backup.automount based on provided instructions.
  • Enabled and started the automount unit using appropriate systemctl commands.

Chapter 4: Automatically Mounting File Systems with Autofs

Lesson 1: Introduction to Autofs

• Installation:
  • Installed autofs package using yum install -y autofs.
  • Enabled and started autofs service using systemctl enable autofs --now.
  • Checked the status of autofs service using systemctl status autofs.
• Configuration Files:
  1. /etc/sysconfig/autofs: Global options for all mounts.
  2. /etc/auto.master: Main configuration file with entries for mounts.
• Mount Points:
  • Created mount points using mkdir.
  • Configured indirect and direct mounts in /etc/auto.master.
  • Created map files for indirect mounts.

Lesson 2: File System Types and Extensions

• File System Types:
  • Discussed various file system types like ISO 9660, UDF, HFS.
  • Explained ISO 9660 extensions: Rock Ridge, Joliet, El Torito.

Lesson 3: Data Encryption

• Installation:
  • Installed cryptsetup package using yum install -y cryptsetup.

Lab: Working with Autofs

Learning Objectives:

• Install the autofs Package and Start and Enable the autofs Service
• Create an Indirect Mount at /mnt/marketing
• Create a Direct Mount at /mnt/admin/data
• Create a Direct Mount at /mnt/user/data

Performing the Lab:

• Installation and Configuration:
  • Installed autofs package and started/enabled the service.
  • Created mount points for marketing, admin, and user data.
  • Edited /etc/auto.master to include entries for mounts.
• Indirect Mount:
  • Created an indirect mount for marketing data.
  • Configured /etc/auto.marketing file with mount options.
• Direct Mounts:
  • Configured direct mounts for admin and user data.
  • Edited /etc/auto.admin and /etc/auto.user accordingly.
• Verification:
  • Restarted autofs service and checked mount points using df -h and ll.

Additional Activities

Mounting and Formatting External Hard Drive

Identification and Confirmation

• Identifying Drive Name:
  • Used lsblk command to identify the name of the external hard drive.
  • Confirmed using sudo blkid /dev/sdc1.

Formatting Process

• Formatting External Hard Drive:
  • Used sudo mkfs.fat -F 32 -n extdrive /dev/sdc1 command to format the drive as FAT32 with label “extdrive”.
  • Verified the formatting using sudo blkid /dev/sdc1.

Result

• Successful Formatting:
  • Successfully formatted the external drive from NTFS to FAT32 file system.

Considerations

• File System Choice:
  • Opted for FAT32 file system for compatibility with both Linux and Windows.
  • Mentioned other file system options like exFAT, NTFS, or ext4 based on specific requirements.
• Alternative Tools:
  • Mentioned the availability of GUI tools like Gparted for more flexibility, similar to Disk Manager in Windows.