Hands-on introduction to cybersecurity: a tool tour
You learn the core ideas of security, try tools like Nmap, Netcat, Wireshark, OpenSSL and Tripwire in your own lab, and protect a small server.
Level 101 · 20 lessons · 21 practice labs
Lessons
Foundations and seeing the network
- Confidentiality, integrity, availability: the three goals of security: You learn, with everyday examples, what it means for data to stay secret, stay unchanged and be available when needed.
- Threat, vulnerability and risk: the difference: Using an office with its door left open, you will tell threat, vulnerability and risk apart and write a simple risk statement.
- Authorised work: using tools only in your own lab: You learn why security tools are used only on systems you are allowed to test and how to draw the limits of your lab.
- Sending messages and files between two machines with Netcat: You will listen on one machine and connect from another with Netcat, seeing for yourself how a TCP connection is made.
- Checking whether a port is open with Netcat: You will quickly check with Netcat whether a service answers on its expected port and confirm a firewall rule.
- Listing devices on your own subnet with Nmap: You will list the live devices and services on your lab network with Nmap and produce a simple inventory table.
- Fast inventory of large ranges with Masscan and rate limits: You will see what load Masscan’s speed puts on a network and take a safe port inventory using a rate limit.
- First capture with Wireshark: inside a web request: You will capture the packets sent when opening a web page with Wireshark and follow the DNS, TCP and HTTP steps in order.
- Finding common misconfigurations on your own web server with Nikto: You will scan your own lab web server with Nikto and read findings such as missing headers and forgotten files.
- Short task: collect the devices and open ports of your lab network in one table
Protecting data and accounts, layering the defence
- Encrypting and decrypting a file with OpenSSL: You will encrypt a confidential document with a password using OpenSSL and show that only someone with the right password can open it.
- Proving a file has not changed with sha256sum: You will take a file’s fingerprint and see how even a one-letter change is noticed at once.
- Watching important files for changes with Tripwire: You will record a baseline of system files with Tripwire and see how an unauthorised change shows up in its report.
- Detecting data hidden in an image with steghide: You will see with steghide that data can be hidden inside an image and learn how to check suspicious files for it.
- Seeing how fast a weak-password ZIP opens with John: You will watch John open a weak-password archive you created within minutes and measure the value of a strong password.
- Seeing password guesses in logs and stopping them with fail2ban: You will recognise repeated failed logins to your lab service in the logs and block the source automatically with fail2ban.
- Adding a second factor (TOTP) to a login script: You will add a one-time code from a phone app to a simple login script so a password alone is no longer enough.
- Drawing a threat map for a simple login service: You will sketch the parts of a small login service and list what could go wrong in each part using the STRIDE method.
- Defence in depth: layer after layer around a service: You will combine a firewall, permissions, encryption and monitoring so a service stays protected even if one control fails.
- Capstone: inspect, protect and report on a small server: With the tools you learned, you inspect a lab server, fix the problems you find and present the before-and-after state in a short report.
Practice labs
- Classify Tarçınlı Fırın's assets by confidentiality, integrity and availability: Read the lab's asset list and hand in a table marking the most important security goal for each asset.
- Separate the threat, vulnerability and risk in this scenario: Label ten statements about Kumsal Turizm's booking server as threat, vulnerability or risk and justify each one.
- Draft the first risk register for a small office: Score five risks from Sedirli Hukuk Bürosu's lab notes by likelihood and impact and produce a prioritised risk register.
- Check whether a port on this server is really open: Test three ports on the lab server with Netcat and record which one is listening, with evidence.
- Add every device on this subnet to the inventory: Find the live devices on the lab subnet with Nmap and fill an inventory table with address, open ports and likely role.
- Inventory a wide range without disrupting service: Scan the lab range with a rate limit, compare the result with the previous inventory and add the undocumented service to the report.
- Find and remove the forgotten default page on this web server: Scan your lab web server, find the default install page, remove it and confirm by rerunning the scan.
- Close the folder with directory listing on and rescan: Find the folder with directory listing enabled on Ayçiçeği Gıda's intranet, fix the configuration and prove it with scan output.
- Sort ten web scanner findings into real issues and false alarms: Verify each finding in the lab web server's scan output, fix the real ones and document the false alarms with reasons.
- Show which details travel in clear text inside a web request: Capture lab traffic, mark the headers in a plain HTTP request and note which information travels in clear text.
- Find the service logging in over clear text and move it to an encrypted one: Identify the lab service whose password crosses in clear text, enable its encrypted version and verify with a new capture.
- Find and report the machine making unexpected connections on the lab network: Inspect the capture in Wireshark, identify the machine talking to an unexpected destination with port and time, and write a short incident note.
- Encrypt a sensitive file and prove only the right key opens it: Encrypt Mercanköşk Otelcilik's guest list with OpenSSL and show it fails with a wrong passphrase and opens with the right one.
- Detect the image that hides embedded data: Inspect the images in the lab folder, find the one carrying hidden data and record how you spotted it in a finding note.
- Measure how weak a poorly protected archive is and fix the policy: Measure how long the lab's password-protected ZIP survives a wordlist, repackage it with strong encryption and write a short policy recommendation.
- Prove with a hash that a downloaded file is unchanged: Compare the lab files' SHA-256 hashes with the published list and flag the file that does not match.
- Set up an integrity baseline for important system files: Build a Tripwire baseline for /etc and /usr/bin on the lab server, make a change and confirm it appears in the report.
- Find and roll back the tampered configuration file on this server: Review the changes in the integrity report, pick out the unexpected one, restore it from backup and show a clean rescan.
- Find and count password-guessing attempts in the logs: Count failed logins in the lab server's auth log by source address and report the busiest source.
- Stop repeated failed logins with fail2ban and test it: Add a fail2ban rule to the lab SSH service, confirm with your own attempts that it blocks, and note the rule settings.
- Add a second login factor to a service and document the layers: Add a TOTP step to the lab login script, update its threat map and summarise the defence layers around the service on one page.
About this course
You learn the core ideas of security, try tools like Nmap, Netcat, Wireshark, OpenSSL and Tripwire in your own lab, and protect a small server.
What you will learn
- Foundations and seeing the network
- Protecting data and accounts, layering the defence
Prerequisites
No prior knowledge is needed; the course starts from zero.
Lab environment
Lessons run in your own Kali Linux terminal in the browser, connected to a private lab network. Nothing to install.
Frequently asked questions
- Is this course right for my level?
- The course is at beginner level; every term is explained where it first appears.
- Is there anything to install?
- No. Every lesson runs in your own lab environment that opens in the browser.
- How do lessons work?
- Each lesson has 8 to 10 steps and a short quiz. Early steps show the command to type, later steps give less help; if two attempts fail, the solution opens.
- Can I try it for free?
- Yes. The first three lessons of every course are free.