joshkerr.com

joshkerr.com

Sign in Subscribe

Hack The Box Write Up for Cache

Hack The Box Write Up for Cache

This is a fun medium skill level server at Hack The Box. It is a linux Ubuntu box and it had a few fun elements. I learned a lot about memcached for this one. It also requires some sqlmap work so if you aren’t familiar with that tool, I

Hack The Box write up for Tabby

Hack The Box write up for Tabby

Tabby [https://www.hackthebox.eu/home/machines/profile/259] is a box on Hackthebox.eu. It was a ton of fun and I learned a lot about Tomcat and LXD. This box was hard for me because I'm a novice. I ended up needing help from the HackTheBox

Hack The Box write up for Remote

Hack The Box write up for Remote

This is my guide to hacking the remote [https://www.hackthebox.eu/home/machines/profile/234] box over at Hack The Box [http://hackthebox.edu]. Getting the user flag was very time consuming. There were a lot of little steps that need to all go right. Getting root was above

Hack the Box write up for Devel

Hack the Box write up for Devel

I've been doing some ethical hacking lately. This is my first writeup for one of the computers I hacked into (legally.) The machine I compromised is called Devel [https://www.hackthebox.eu/home/machines/profile/3] on Hackthebox.eu [http://hackthebox.edu]. I'm a beginner when

Hack The Box write up for Traceback

Hack The Box write up for Traceback

This was a great box! This article is my guide for hacking traceback, one of the retired machines at HackTheBox.eu [http://hackthebox.eu]. This is my first hacking guide, so hopefully i'm doing this correctly. I enjoyed this box. It was right at my skill level and

Stunning sunset in downtown Austin, TX

Stunning sunset in downtown Austin, TX

I took this photo from my balcony. I used my iPhone XS (which takes pretty great photos.)

How to move your blog from Medium to Wordpress

How to move your blog from Medium to Wordpress

Medium recently shut down their third-party API without any notice. I was immediately incensed and decided to migrate my blog away from Medium. You can read more angst on this post and followup discussion on HackerNews about why I left. This article will show you how to migrate your content

Proof that the Universe will repeat itself

Proof that the Universe will repeat itself

What if I told you the universe is destined to repeat itself—and that includes you? Before you dismiss me as having spent too much time staring at the night sky, let me introduce you to one of the most mind-bending theorems in mathematics: the Poincaré recurrence theorem. It'

How canaries protect us from the snooping US Government

Privacy Featured

How canaries protect us from the snooping US Government

In the early days of coal mining, workers faced an invisible killer: toxic gases like carbon monoxide and methane that could accumulate without warning. Their solution was elegantly simple—bring a canary into the mine. These small birds, more sensitive to poison than humans, would stop singing or collapse before

Medium needs to support Latex for math and science

Medium needs to support Latex for math and science

Medium is a great story telling platform but it falls short for publishing any serious science and math related articles. The big issue with this type of content on Medium is that it relies on math which can’t be easily rendered on Medium. Most writing platforms struggle with math

The Infinite Monkey Theorem

big numbers Featured

The Infinite Monkey Theorem

The infinite monkey theorem is a bar in Austin, TX, but it is also a very cool mathematical theorem that deals with very big numbers. This article is about the theorem which has become very popular in recent times. The theorem as I understand it is as follows: A monkey

1+2+3+4+... = -1/12

1+2+3+4+... = -1/12

This is a remarkable and hard to believe consequence in mathematics. If you were to sum the natural numbers all the way to infinity, you would get \(-\frac{1}{12}\). $$ 1+2+3+4+5+6... = -\frac{1}{12} $$ This is just insane. It makes no sense that

Graham's number - big numbers blow my mind!

Graham's number - big numbers blow my mind!

What's the biggest number you can think of? A million? A billion? The number of atoms in the observable universe (roughly \(10^{80}\))? Whatever you're imagining, I promise you it's basically zero compared to Graham's number—a number so incomprehensibly vast that

The longest finite time ever calculated by a physicist

The longest finite time ever calculated by a physicist

I've written quite a bit on big numbers [https://joshkerr.com/tag/big-numbers/] because I find them fascinating. Two of the areas where you find interesting big numbers are astronomy and cosmology. For example the observable universe is thought to be 93 billion light years across (That'

The Ackermann function explained

The Ackermann function explained

The Ackermann function is a recursive function originally invented by Wilhelm Ackermann. It is one of a series of mathematical functions that quickly generates enormous numbers. If you haven't read my article on Knuth's up arrow notation, I recommend taking a look at it first before

Knuth's up arrow notation explained

Knuth's up arrow notation explained

When we talk about large numbers, we are talking about numbers that are bigger than what we use in our ordinary day to day life. These are numbers typically used by mathematicians in fields such as cosmology, cryptography and statistical mechanics. Since big numbers have a lot of digits, it

How big is googol?

How big is googol?

Googol is a big number. The search engine was famously named after it. There are several ways that we can think about Googol. Written with exponents, the number can be represented like so: $$ 10^{100} $$ If you expand it out you would write a 1 followed by 100 zeros: 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Mind blown: the fast growing hierarchy for laymen — aka enormous numbers

Mind blown: the fast growing hierarchy for laymen — aka enormous numbers

WARNING — I’m not a mathematician so I probably made a bunch of errors. Please leave corrections in the comments. A few years ago I stumbled upon an article by famed computer scientist and quantum physics expert Scott Aaronson titled “Who can name the bigger number?” The article inspired a

Who can name the biggest number contest

Who can name the biggest number contest

Imagine a simple game: two people stand at a whiteboard, and each tries to write down the biggest number they can. Whoever writes the larger number wins. No infinities allowed. No saying "your number plus one." Just pure mathematical creativity. Sounds easy, right? You might start by filling

9/11 from the eyes of a New Yorker

9/11 from the eyes of a New Yorker

I witnessed the attacks of September 11th 2001 first hand in New York City as the World Trade Center towers collapsed before my very own eyes. It was a painful day for many people all over the world but it was uniquely different for those of us that lived in

Top 10 greatest music artists of all time.

Top 10 greatest music artists of all time.

This is my list of the greatest music artists of all time. My only criteria is that they have to be modern (so Beethoven doesn’t qualify.) For each selection I’ve listed the reasons why they are on my list. I mostly looked at each artist’s influence both

Donald Trump’s valet guy thinks Trump is in over his head

Donald Trump’s valet guy thinks Trump is in over his head

I attended a wedding a couple of weekends ago at Trump’s Mar A Lago estate & club in Palm Beach Florida. After a glorious wedding party I stood in the front driveway waiting for my Uber to take me back to my hotel. One of the valets came over

The Chromebook Pixel is Medium’s best writing platform

The Chromebook Pixel is Medium’s best writing platform

A bespoke writing experience from the Google’s top of the line notebook I love to write on Medium. The supplied editor is gorgeous and makes it drop dead easy to produce beautiful articles. Unfortunately, the editor doesn’t do much to help with my atrocious grammar. Without proper grammar,

Star Wars Rogue One — you have to see these screenshots

Star Wars Rogue One — you have to see these screenshots

If you haven’t seen the teaser trailer for the new Star Wars movie Rogue One you need to stop what you are doing and go watch it: The story takes place before Star Wars IV A New Hope and follows the adventure of the rebels who steal the Death

I trust Medium to host my blog and you should too

I trust Medium to host my blog and you should too

Update: On February 1st, 2019, I moved my website away from Medium and back to Wordpress. I'm currently hosting my site on Wordpress.com. I mention the reasons for the move in this blog article. A few hours ago I completed the migration of my personal blog to