How it works

Hack The Flag runs in your terminal. There is no website to log in to and no client to install. You connect with SSH and everything happens there.

1. Connect

ssh app.hacktheflag.net

There is no sign-up form and no password. The server identifies you by your SSH public key. The first time you connect it creates a player for that key and gives you a nickname. Every later connection from the same key is the same player.

That means you need an SSH key. If ls ~/.ssh/*.pub shows nothing, create one first:

ssh-keygen -t ed25519

It also means your key is your account. Connect from another machine with a different key and you start from zero, so copy your key if you want to play from two computers.

2. Pick a riddle

The main menu has three places to go: Riddles, Scoreboard and My Progress. Move with the arrow keys, open with Enter, go back with Esc, quit with q.

Riddles lists every challenge with its difficulty and whether you have solved it. Open one to read it. Each riddle is a cipher or a puzzle that leads to one answer.

3. Submit the answer

Type your answer into the riddle screen and press Enter. You are told straight away whether it is right. Capital letters do not matter. Wrong answers cost nothing, but submissions are rate limited, so guessing in bulk will not work.

Flags look like this:

<HTF-this_is_a_flag/>

4. Scoring

The first player to solve a riddle gets one extra point, which is what separates players who are otherwise level. Only solves made before the edition closes count toward the scoreboard.

New to this?

The blog has guides on the tools and ciphers you are likely to meet.