Archives

This page is simply a placeholder where I can have links to archives of past efforts I’ve been involved with, mainly from the late 90s/early 2000s, in case they come up in future conversation. And for clarification, by “archives” I really mean “links from my site that redirect to pages archived on the Wayback Machine”.

The list:

  • SPAM-L FAQ – I maintained the FAQ for the SPAM-L from the late 90s until the list was shut down in the late 2000s. The list had hundreds of members representing organizations from around the world.
  • spam.abuse.net – This was the original website that explained “what is spam”, “why is it bad”, etc. back when the Internet was much more of a “Wild Wild West”. I was a contributor to the site and my name can be found in the list of signatories at the bottom of the page.
  • CAUCE – The Coalition Against Unsolicited Commercial Email. I co-founded this group back in 1998 and we grew to over 30,000 members. Our goal was to see legislation crafted to amend the Junk Fax Law (47 USC 227) to apply to email. While we were not successful, we did succeed in bringing much public attention to the spam problem.
  • Turntide – TurnTide was a startup that made an anti-spam router. It would sit in front of your mail server and process all traffic on port 25. If a particular IP address was sending spam, we wouldn’t block them, just slow them down with traffic shaping, causing queues to fill up on their end. Customers loved it, spammers hated it. 5 months in, we were bought by Symantec for $28 Million.

HOWTO: Safely use “git rebase -i”

Git is a very powerful revision control system used in software development, and at this point, is effectively the industry standard. One of the things that makes Git so powerful is that there are all sorts of low-level operations that developers can do in it. This includes everything from tagging releases, to having an insane number of branches, to painless merging of said branches, to rewriting history.

“I am serious. And don’t call me Shirley.”

If you’re new to Git, your brain probably threw an exception when reaching the end of the paragraph as you thought to yourself, “Wait WHAT? Why would you want to REWRITE HISTORY?” Good question! Normally, you don’t want to mess history in a revision control system. But sometimes you may want to or even need to. A few possible reasons for rewriting history include:

  • Feature Branch “B” is a branch of Feature Branch “A” and you want to merge B’s changes to master, but not A’s.
  • Squashing all the commits in a feature branch to a single commit, after having previously pushed those commits.
  • A developer made a commit with something that doesn’t belong in Git, such as PII or credentials.
  • You want to “clean up” the commit history a little.

Whether any of the above are fully valid reasons or not is something up to you and your dev team.

That said, rebasing is not something you want to experiment with for the first time on your production repo. It’s just a bad idea. So I built a playground/lab where anyone can experiment with git rebasing in an isolated and local environment, which can be stood up in seconds. Here’s how to get started:

git clone git@github.com:dmuth/git-rebase-i-playground.git
cd git-rebase-i-playground
./init.sh
Continue reading “HOWTO: Safely use “git rebase -i””

Great Palace Map from Zelda II: New Adventure of Link

I’ve been trying to keep myself amused during the COVID-19 shutdown, and as such have been trying a number of new things. One new thing I decided to look into is playing hacked NES ROMs. It turns out there are a great number of ROM hacks out there, with the website ROMhacking.net listing over 4,600 hacked ROMs as of this writing.

While looking into hacked ROMs, I quickly learned that ROM hacks fall into one of 3 main categories: “really good”, “really bad”, and “joke”. I spent some time looking around, and found one particular ROM which I found in the “really good” category: Zelda II: New Adventure of Link, created by someone named HollowShadow. So I downloaded OpenEmu, grabbed the ROM hack, bought a USB NES controller, and got to playing!

Being a big fan of Zelda 2, I had no problem playing through the vast majority of the ROM. It’s when I got to the final palace is when the game became quite difficult, and quickly got lost.

What I needed was a map, but because this was a ROM hack, there wasn’t a whole lot available to me in the way of resources.

So I decided to make a map.

Continue reading “Great Palace Map from Zelda II: New Adventure of Link”

Philadelphia Public Transit vs COVID-19

We’re well past a month into the COVID-19 shutdown, and I noticed that fewer and fewer trains were running on Regional Rail each day. I knew that SEPTA had decreased their service due to less riders, but I wondered just how strict the service cuts were. I also wondered if more or perhaps less trains were running on time.

Fortunately, I have several years worth of train data due to running SeptaStats.com, so I could answer these questions myself!

I started off by firing up Splunk Lab then went for a walk while it took 15 minutes or so to load the data up. I came back, and decided to see where we were:

“That’s one big Twinkie.”

That’s well north of 60 million data points. While I could crunch that data as-is, it would take longer for me to run my subsequent queries as well as look for trends in the data. I ended up writing a couple of scripts to summarize that data on a daily basis, so that I can get a bucketed breakdown of late trains for the entire day. We’ll get back to that bucketing later, because I first want to talk about train volumes.

I figured that with the perceived dropoff in service, I could look at how many distinct trains (identified by train number) each day. Sure enough, there was a drop off in train service levels:

“Symmetrical book stacking… just like the Philadelphia mass turbulence of 1947!”

Things started to get serious the week of Monday, March 16th. In fact, that was the last day of “normal” service on Regional Rail. Starting on Tuesday the 17th, the number of trains per weekday went from nearly 500 to about 362, with the weekends unaffected.

Continue reading “Philadelphia Public Transit vs COVID-19”

How to Watch Netflix with Friends during COVID-19

With this whole COVID-19 pandemic going on, we all have to socially isolate ourselves in our homes in order to flatten the curve of cases, and this is likely to continue for some time.

I’ve looked into ways to watch Netflix with friends online, and after trying several different “solutions”, I found one which works quite well: Netflix Party

In order to use Netflix Party, each person will need a desktop or laptop running the Google Chrome web browser. If you don’t have Chrome installed, ask your child to install it on your computer for you. If you don’t have any children, text your neighbor’s kid for installation instructions.

To install Netflix Party click “Install Netflix Party” from the Netflix Party website. This will take you to the plugin page on the Chrome Web Store. Click the “Add to Chrome” button to install it.

“I am serious. And don’t call me Shirley.”

You’ll be prompted to install the extension in Chrome. Do that.

“That rug really tied the room together, did it not?”
Continue reading “How to Watch Netflix with Friends during COVID-19”

Welcome to dmuth.org!

Welcome to my website and blog! It has been been around in one form or another for well over a decade. It’s changed purposes a few times, and at this point is now a mostly tech blog where I share things I’ve learned or made. Feel free to have a look around, or consider checking out some of the more popular posts I’ve made over the years:

“Who disturbs my nap?”

Thanks for visiting, and feel free to reach out if you have any comments or just want to chat!

SSH At Scale: CAs and Principals

If you manage Linux servers over the Internet, you use SSH to connect to them. SSH lets you have a remote shell on a host over an encrypted channel so that an attacker cannot watch what you are doing over the network. In this blog post, I’m going to talk about using SSH at scale across thousands of posts.

Phase 0: Passwords

When you get started with SSH for the first time, you likely won’t have keys set up and will instead use passwords to authenticate to your servers. It will look something like this:

ssh dmuth@cheetah.dmuth.org
dmuth@cheetah.dmuth.org's passsword: ********
$ 

You use SSH to connect to the server, type in your password, and you’re good to go. That’s fine for small scale, such as managing a single server, but it doesn’t come without downsides. Specifically, you won’t be able to easily use a tool such as Ansible nor do code checkins with Git.

And that’s actually a bigger problem than it sounds, because if you make it harder to use a tool, that tool will be used far less often. This can lead to things such as configuration drift due to Ansible being run less often, or giant code pushes happening once a day if Git is being run less. And giant code pushes are a particular problem, because if other engineers have written code, you’ll have to do a merge, and if a bug presents itself, you’ll now have to think back to what you did 8 hours ago, not 8 minutes ago. Having to type in a password every single time will also slow down the rate of deployment, which in turn slows down the rate of product releases. Not good.

Seriously, don’t use SSH with a password for any reason other than as a stepping step to using keys. And that brings us to…

Continue reading “SSH At Scale: CAs and Principals”

Staying Safe Online: A Guide for Beginners and Non-Technical People

Perhaps you’re worried about being doxxed, perhaps you’ve received some specific threats, maybe you just want to increase your security. No matter the reason, this article is for you! Below I will list a collection of good practices to keep you and your accounts safe online. I fully expect to update this post as things change in the future.

I have tried to put things in a logical order, with some later steps depending on earlier steps, and some things that may be considered “controversial” towards the end.

This post was last updated on Jan 2, 2020.


Passwords

Let’s start with passwords. I shouldn’t have to say this, but I will do so anyway: do not reuse passwords. Reusing passwords mean that if a single account provider is breached and your plaintext password is recovered, you now have additional accounts at risk of compromise. This has happened before.

Anyone in a hoodie is NOT to be trusted.

I recommend using a password manager such as LastPass to keep track of your passwords. While having your passwords stored in an app that uploads them somewhere increases your risk slightly, I feel it is outweighed by using a different password for each service. For passwords themselves, you can use random characters or a system such as Diceware to create long passwords that are easier to remember. While the latter is slightly less secure, a password that can be remembered is one less password to store into a password manager.

Continue reading “Staying Safe Online: A Guide for Beginners and Non-Technical People”

“Hey Siri! Is SEPTA F*cked?”

I’m happy to announce that I’ve created shortcuts in IOS so that Siri can now tell you if SEPTA is fucked!

Before you can get started, you will need to configure IOS to allow Untrusted Shortcuts. There are more detailed instructions on Apple’s support website, but it comes down to doing these two things:

  1. Go into Settings > Shortcuts
  2. Turn on the setting that says “Allow Untrusted Shortcuts”.
“Hey Siri, Is SEPTA Fucked?”

If you don’t see the setting mentioned in Step 2), you will need to open the Shortcuts app, run at least one shortcut, and come back to that screen. (Thanks, Apple!)

If you need further help allowing Untrusted Shortcuts, this writeup is more thorough and includes screenshots.

Anyway, once you have enabled Untrusted Shortcuts, you can click on any of these links to add shortcuts to Siri that will query the website’s API and report back on the status of Regional Rail, Busses, or both:

Once a Shortcut is loaded, you can run the shortcut by either tapping on the Shortcut in the Shortscuts app, or simply by asking Siri the question mentioned above.

Feel free to try this out, and let me know in the comments how it works for you!

Special thanks to @RadioColin over on Twitter for the initial draft of the shortcut!