From aeef05a47fae9b532aa0471e92a8a33e105705ed Mon Sep 17 00:00:00 2001
From: Michael Zhang <mail@mzhang.io>
Date: Wed, 18 Sep 2024 01:14:15 -0500
Subject: [PATCH] faq page wip

---
 .../index.lagda.md                            |   2 +-
 src/content/posts/2024-09-18-ctf-faq.md       | 101 ++++++++++++++++++
 2 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 src/content/posts/2024-09-18-ctf-faq.md

diff --git a/src/content/posts/2024-09-15-circle-is-a-suspension-over-booleans/index.lagda.md b/src/content/posts/2024-09-15-circle-is-a-suspension-over-booleans/index.lagda.md
index 851c0c2..7998b49 100644
--- a/src/content/posts/2024-09-15-circle-is-a-suspension-over-booleans/index.lagda.md
+++ b/src/content/posts/2024-09-15-circle-is-a-suspension-over-booleans/index.lagda.md
@@ -135,7 +135,7 @@ rightInv (loop i) =
   -- Σ2→S¹ (merid false) = loop
   -- Σ2→S¹ (sym (merid true)) = refl_base
   cong (λ p → p i) (
-    cong Σ2→S¹ (merid false ∙ sym (merid true)) ≡⟨ congFunct {x = merid false _} Σ2→S¹ refl refl ⟩
+    cong Σ2→S¹ (merid false ∙ sym (merid true)) ≡⟨ congFunct {x = merid false {!   !}} Σ2→S¹ refl refl ⟩
     loop ∙ refl ≡⟨ sym (rUnit loop) ⟩
     loop ∎
   )
diff --git a/src/content/posts/2024-09-18-ctf-faq.md b/src/content/posts/2024-09-18-ctf-faq.md
new file mode 100644
index 0000000..6107c7a
--- /dev/null
+++ b/src/content/posts/2024-09-18-ctf-faq.md
@@ -0,0 +1,101 @@
+---
+title: CTF FAQ
+date: 2024-09-18T00:49:55-05:00
+tags: [ctf]
+draft: true
+---
+
+There's a lot of foundational stuff that is sometimes not obvious to people who are just starting out in CTF.
+
+### What does nc \<ip\> mean?
+
+For example,
+
+```
+nc chal.examplectf.com 12345
+```
+
+This is a quick way of saying that a server is running at a specific IP on a specific port.
+`nc` stands for netcat, which is a tool that lets you talk to a server through your command line.
+
+> [!admonition: NOTE]
+> This also means that the flag is hidden on the server, and will **not** appear in any of the files that have been distributed to you.
+
+In reality, you'd probably only use `nc` to play around with it initially.
+You'd probably want to move to using a script soon, because you are usually given a copy of the program to play around with locally.
+
+With vanilla Python, you can open a [socket] and replicate the `nc` behavior with:
+
+[socket]: https://docs.python.org/3/library/socket.html
+
+```py
+import socket
+s = socket()
+s.connect(("chal.examplectf.com", 12345))
+```
+
+Alternatively, use [pwntools]:
+
+```py
+from pwn import *
+r = remote("chal.examplectf.com", 12345)
+```
+
+### Why do I get a binary and a C file?
+
+The binary is often provided because the specific addresses are meaningful to construct an attack.
+Sometimes a libc is also provided to help craft attacks that need specific libc addresses.
+
+Using something like [pwntools] makes it easy to do exploration and perform automated searches for addresses through a binary locally very quickly, and then swap out the target to the server once you've found a method to crack the binary.
+
+[pwntools]: https://pwntools.com
+
+### I get some text file with values like N, e, c. What does this mean?
+
+These are usually some values for working with a cryptosystem called [RSA].
+
+[RSA]: https://en.wikipedia.org/wiki/RSA_(cryptosystem)
+
+* $N$ is the modulus. It's part of the public key. It's calculated with $N = p \times q$, but usually $p$ and $q$ are left as private
+* $e$ is the public exponent. It's also part of the public key
+* $c$ is the ciphertext.
+* $m$ (if included) is the message, but this is usually the thing you're looking for
+
+Lots of CTFs will do modified versions of RSA as a puzzle.
+
+> [!admonition: NOTE]
+> If the $N$ is just given to you directly instead of in a script, just go ahead and chuck the $N$ into [factordb] to see if it's already been factored!
+
+[factordb]: https://factordb.com/
+
+### I need to quickly convert some data
+
+[CyberChef] is my tool of choice when it comes to this stuff.
+
+[cyberchef]: https://gchq.github.io/CyberChef/
+
+### I have a file but I don't know what it is
+
+Plug the file through the [file] command!
+It'll tell you what kind of file it is, by looking at the first few numbers. For example:
+
+[file]: https://en.wikipedia.org/wiki/File_(command)
+
+```
+$ file binary
+binary: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=62bc37ea6fa41f79dc756cc63ece93d8c5499e89, for GNU/Linux 3.2.0, not stripped
+```
+
+This means it's an executable program.
+
+Another useful tool is [binwalk], which tells you if there's other files packed in there.
+This is sometimes useful for some forensics challenges.
+
+[binwalk]: https://github.com/ReFirmLabs/binwalk
+
+### I'm on Windows. What do?
+
+Install [WSL] or [dual boot].
+
+[WSL]: https://learn.microsoft.com/en-us/windows/wsl/about
+[dual boot]: https://wiki.archlinux.org/title/Dual_boot_with_Windows