LFCS Mock Exam

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This mock exam is designed to test your knowledge across all LFCS topics: Operations, Networking, Storage, Essential Commands, and Users & Groups.

Instructions

• Complete the exercises without looking at the answers.
• The answers are provided at the end of the document.

Part 1: Operations & Deployment

1. Configure a system to automatically load a kernel module dummy_module at boot.
2. Identify a device connected via PCI and check if a kernel module is loaded for it.
3. Create a cron job to run /usr/local/bin/backup.sh every day at 2:30 AM.
4. Check if the system is vulnerable to the Meltdown CPU flaw.

Part 2: Networking

1. Assign a static IP address 192.168.50.10/24 with gateway 192.168.50.1 to interface eth0.
2. Configure the system to synchronize time with pool.ntp.org.
3. Allow SSH connections on port 2222 through the firewall.
4. Add a static route to reach network 10.10.0.0/16 via gateway 192.168.50.254.

Part 3: Storage

1. Create a 10 GB LVM logical volume named lv_data in volume group vg01.
2. Format it with ext4 and mount it on /mnt/data.
3. Create a 2 GB swap file and enable it.
4. Mount an NFS share server:/share on /mnt/nfs automatically at boot.

Part 4: Essential Commands

1. Check which process is consuming the most CPU and kill it.
2. Find the 10 largest files in /var/log.
3. Generate a self-signed SSL certificate valid for 365 days.
4. Clone a Git repository and push a file named README.md after adding a new line.

Part 5: Users & Groups

1. Create a new user developer1 with bash shell and home directory.
2. Add this user to a group developers.
3. Set the maximum number of open files for developer1 to 4096.
4. Set ACL so that developer1 has read/write access to /var/www/html/index.html without changing the file’s group ownership.

Answers (Do not read until done!)

Part 1: Operations & Deployment

1. echo "dummy_module" | sudo tee /etc/modules-load.d/dummy_module.conf
2. lspci -v and look for kernel driver in use
3. crontab -e → 30 2 * * * /usr/local/bin/backup.sh
4. grep bugs /proc/cpuinfo or cat /proc/cpuinfo | grep -i meltdown

Part 2: Networking

1. sudo nmcli con mod eth0 ipv4.addresses 192.168.50.10/24 sudo nmcli con mod eth0 ipv4.gateway 192.168.50.1 sudo nmcli con mod eth0 ipv4.method manual sudo nmcli con up eth0
2. sudo apt install chrony sudo nano /etc/chrony/chrony.conf → add server pool.ntp.org iburst sudo systemctl restart chrony
3. sudo firewall-cmd --permanent --add-port=2222/tcp sudo firewall-cmd --reload
4. sudo ip route add 10.10.0.0/16 via 192.168.50.254

Part 3: Storage

1. sudo lvcreate -L 10G -n lv_data vg01
2. sudo mkfs.ext4 /dev/vg01/lv_data sudo mkdir -p /mnt/data sudo mount /dev/vg01/lv_data /mnt/data
3. sudo fallocate -l 2G /swapfile sudo chmod 600 /swapfile sudo mkswap /swapfile sudo swapon /swapfile
4. /etc/fstab entry: server:/share /mnt/nfs nfs defaults 0 0

Part 4: Essential Commands

1. top or ps aux --sort=-%cpu | head → kill <PID>
2. du -ah /var/log | sort -rh | head -10
3. openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout server.key -out server.crt
4. git clone <url> echo "new line" >> README.md git add README.md git commit -m "Add new line" git push origin main

Part 5: Users & Groups

1. sudo useradd -m -s /bin/bash developer1 sudo passwd developer1
2. sudo groupadd developers sudo usermod -aG developers developer1
3. ulimit -n 4096 (temporary) or add to /etc/security/limits.conf: developer1 hard nofile 4096
4. setfacl -m u:developer1:rw /var/www/html/index.html