Find the bandwidth hog by viewing all network connections passing through your DD-WRT router
Something was using all of my upstream bandwidth, wasn’t sure what device or who it was (had friends over). To get to the bottom of it quickly, a simple command can be run from the DD-WRT web-based gui that will show all network connections on your DD-WRT router.
Just follow these 5 easy steps below:
1. Login to your router’s web interface.
2. Click the “Administration” tab, and then click the “Commands” tab.
3. In the text area to enter commands, enter this:
cat /proc/net/ip_conntrack
4. Click the “Run Commands” button below where you entered the command above.
Once you’ve clicked the “Run Commands” button, wait a few seconds, and you’ll eventually see some output similar to what you see in the image above, below is the raw text from the image:
Now the key to tracking down the offending user/device is to look for a source IP (almost always a non-routable IP, like 192.168.1.x, 10.10.10.x or whatever) that shows up a LOT more often than other non-routable IP’s.
Once you’ve found that IP, go to the “Status” tab in the DD-WRT web interface, click “LAN”, find the IP that you suspected was the culprit from above and make a note of the MAC address associated with that IP.
Manipulate Mailgun Bounce Lists: Show, Add, and Delete Email Addresses. All from the terminal.
I recently came across a situation where a client reached their disk usage limit. As a result, they were unable to receive emails. This went un-noticed for a couple days (I didn’t manage the server at the time, I do now).
This client has a couple different WordPress sites with several employees receiving various notification emails. All their sites use Mailgun and the Mailgun WordPress plugin for sending emails. During the time they were unable to receive email, a few employee email addresses got placed on a Mailgun bounce list with a status of 550 Administrative prohibition.
Bounce list stores events of delivery failures due to permanent recipient mailbox errors such as non-existent mailbox. Soft bounces (for example, mailbox is full) and other failures (for example, ESP rejects an email because it thinks it is spam) are not added to the list.
Subsequent delivery attempts to an address found in a bounce list are prevented to protect your sending reputation.
I first noticed the bounce issue in the logs, like in the image below. After not being able to find a way to manage email addresses on the bounce list from the browser, I hit up Google and was pleased to find that you can interact with Mailgun bounce lists via their API.
Show Email Addresses in the Mailgun Bounce List
To list email addresses on the bounce list, do something like this on the terminal/command line, replacing key-xxx-xxx with your actual Mailgun API key:
You can find your Mailgun API key on the Mailgun dashboard, under API Keys. The Mailgun API will return JSON, which is a bit difficult to read in the terminal. I usually copy the output and paste it into this JSON formatter, which makes the data much easier to read, as you can see in the screenshot above.
Even when the formatted JSON in it’s raw form is easier to read. See, here’s the returned JSON, in it’s original form:
Now here’s the pretty, formatted JSON as raw text:
Much easier to read, right? Those of you using REST clients like Postman will have your results automatically prettified, removing the need using a site like the JSON formatter I typically use.
Delete an Email Address from the Mailgun Bounce List
If you’ve found an email address you’d like to remove from the Mailgun bounce list, or already know the email you want to remove, do this from a terminal and replace email@somedomain.com with the real email address to delete. And of course, replace key-xxx-xxx with your actual Mailgun API key:
Sometimes you may wish to manually add an email address to the Mailgun bounce list. This can be done very easily with the CURL command below. It will add email@somedomain.com to the Mailgun bounce list, so make sure to change that to the email you really want to add to the list.
Not much concerning Mailgun bounce lists specifically. It’s possible to add multiple addresses to a bounce list at once, but that gets a little more difficult from the terminal as it requires sending JSON to the Mailgun API. Using a client like Postman would be a better option if you intend on sending much data.
The Mailgun API can be used to do all sorts of stuff, like pull stats and to create new domains. It’s a powerful API and one of my favorites to work with.
A Dockerfile That Provides Quick WordPress Development Environments
Back in May of this year I started playing around with Docker quite a bit. Took me a bit to wrap my brain around everything Docker can do, wish I had read this article from Adam Ierymenko before starting.
Anyway, Docker describes itself as such:
Docker is an open platform for building, shipping and running distributed applications. It gives programmers, development teams and operations engineers the common toolbox they need to take advantage of the distributed and networked nature of modern applications.
I’m not using Docker to it’s fullest extent, not even close. I mostly use it for setting up quick WordPress development environments for building client sites or just to do some testing.
I came across an outdated Dockerfile that had exactly what I needed but lacked the ability to SSH to the Docker container. I forked it on GitHub and added some modifications (like SSH).
It’s on the Docker Hub Registry, making it super easy to use. There’s a few items on the to-do list, but the one I want to take care of first is adding support for Docker Compose, which will make installation even easier.
To get started with this Docker image, you just need to have Docker installed and then run the following command:
Once you’ve got the Docker image pulled, fire up a new container like with the command below. It will create a new Docker container named project-name.
Give it a bit to get everything setup then navigate to http://127.0.0.1:80 in your browser to access your new WordPress install.
For more information I suggest checking out the readme. Every time that I push commits to GitHub, a new build of the Docker image will automatically be built as I’ve got it setup as an automated build repository at the Docker Hub Registry. Pretty nifty.
So, I’m relatively new to Docker, if you’re a pro and see something I should be doing differently, please let me know. Any advice on setting up Docker Compose for this project would be great, too (if I’m not mistaken, it just involved linking multiple containers together).
Keybase.io is quite simple, basically a web interface and command line client that makes PGP more user-friendly. At the same time, it makes it easy to get someones public key, and know it’s the correct key.
Keybase.io allows you to encrypt, decrypt, sign, and verify messages to other keybase.io users. The Keybase.io homepage has an excellent description on the inner workings and how to make use of the command line client.
I like how the purpose of the Keybase.io website, as opposed to the command line client, is described:
Keybase.io is also a Keybase client, however certain crypto actions (signing and decrypting) are limited to users who store client-encrypted copies of their private keys on the server, an optional feature we didn’t mention above.
On the website, all crypto is performed in JavaScript, in your browser. Some people have strong feelings about this, for good reason.
Everything has it’s flaws, though. So for me, Keybase.io is an easy way for me to communicate securely with those I need to do so with. I’ll likely continue using it, but need more people I communicate with frequently to be members.
Invites
I do have invites for Keybase.io. I’ll only send them to people I know. If you’re a regular here, a client of mine, or old online friend, you qualify. Real world friends and family obviously qualify.
So easy to miss, but so important for SSH Private Key Authentication
I don’t allow password logins on any of my servers. Can only login via SSH key based authentication. No root login is allowed, and I specify every user that’s allowed to login via SSH, ie: me.
None of that will be of interest to you if you already know how to generate SSH keys.
I’ll SSH into my new Droplet, only to be rejected. I immediately know why, because it’s happened so many times. It’s due to incorrect permissions on your Droplet, VPS, server, whatever.
For SSH private key authentication to work, the ~/.ssh/authorized_keys file and the ~/.ssh folder need specific permissions:
After you’ve followed those steps, change permissions on the ~/.ssh/authorized_keys file again and on the ~/.ssh folder again. Like so from your terminal:
If you do allow password logins, I’d love to hear what scenario causes you to need to allow password logins. Let me know in the comments if you don’t mind.
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