Start CTF (capture the flag) practice with a small kit: a packet analyzer, a reverse engineering framework, a scripting language with a CTF library, a web proxy and a notes file. Learn each against practice challenges, and test only systems you own or have explicit permission to attack.
What is a CTF?
A capture the flag event gives you deliberately vulnerable targets or puzzles. Solving one reveals a text string, the flag, which you submit for points. Challenges usually fall into groups: web, binary exploitation, reverse engineering, cryptography, forensics and miscellaneous puzzles.
The skill is not memorizing tools. It is reading something unfamiliar, forming a guess and testing it. Tools just shorten the loop.
Which tools fit each category?
Forensics and network puzzles: Wireshark. Wireshark is a free, open-source packet analyzer. Given a captured network file, you can filter by protocol, follow a conversation and pull a file out of a stream. Many beginner forensics challenges are solved by reading one conversation carefully.
Reverse engineering: Ghidra. Ghidra is a software reverse engineering framework released by the US National Security Agency as open source. It disassembles a compiled program and can show an approximate source-code view, so you can read what a binary does without the source. Start with small programs that check a password and work out what it expects.
Binary exploitation and scripting: pwntools. pwntools is a Python library described by its authors as a CTF framework and exploit development library, designed for rapid prototyping. It helps you connect to a challenge server, pack and unpack data, and script interactions. Use it for challenge servers built for practice, never against live systems.
Web: an intercepting proxy and a browser's developer tools. Learn to read requests and responses, change a parameter and replay a call.
Everything else: a notes file and a terminal. Basic command-line skills, such as searching text, decoding common encodings and inspecting file types, solve many early puzzles. Keep a log of what you tried. You will repeat yourself otherwise.
How should a beginner practice?
A constructed example: a learner opens a forensics challenge with a capture file. They open it in Wireshark, filter to web traffic, follow one stream and notice a file download. They export the file, check its type and find that it is a compressed archive. Inside is the flag. The steps were simple. The habit that mattered was following one thread at a time and noting each step.
Start with beginner-friendly platforms and public practice sets that are built for learning. Read write-ups after you solve a challenge, or after you have been stuck for a fixed time, to see another approach. Join a team. Explaining your thinking to others is one of the fastest ways to improve.
What are the rules?
Only attack what you have permission to attack. CTF targets are set up for it. Real websites, other people's networks and live services are not. Check an event's rules, and do not share flags or solutions during a live competition unless the rules allow it. Treat challenge files with care too: a binary from a challenge may be malicious, so open it in a virtual machine you can delete.
How to check or apply this
- Install a virtual machine for practice and keep it separate from your daily computer.
- Learn Wireshark first: capture, filter, follow stream and export an object.
- Pick up Python basics, then try pwntools against a practice server.
- Open small programs in Ghidra and write down what each function does.
- Learn to read raw web requests in your browser tools or a proxy.
- Keep a notes file for every challenge: what you tried, what failed and what worked.
- After solving or timing out, read a public write-up and compare.
Quick check
Is it legal to use these tools?
The tools are public and widely used for learning and defense. Legality depends on what you point them at. Use them only on systems you own or are explicitly authorized to test.
What is a flag in a CTF?
A flag is a secret text string hidden in a challenge. You find it by solving the puzzle and submit it to prove you solved it.
Sources
Last reviewed: 18 October 2026.
