If you want to use Docker on servers or virtual machines, technical limitations can sometimes lead to a situation in which – even without intentional limitation – it is not possible to access the outer world from a docker container. Read more “Docker MTU issues and solutions”
In order to gain experience with a Kubernetes cluster or to be able to experiment with it, a functioning cluster is required. Since most conceptual challenges do not require a high performance test cluster, it is also sufficient to build a smaller and therefore more cost-effective one. For this reason I decided to set up a Raspberry Pi Kubernetes Cluster for testing purposes.
- 4x Raspberry Pi 3 Model B+
- 4x microSD Card (I’m using SanDisk Ultra 64GB)
- Power supply unit for the Raspberry Pi devices. You can also use any other 5V power source which provides enough current.
- 4 Micro USB cables for connecting the power suppy unit
- 4 Layer Acrylic Cluster Case
If the Raspberry Pis are not to be connected via WLAN but cable, the corresponding network components are also required:
- 5 Port Switch
- 4 short ethernet cables
The website of Hypriot has a very good tutorial how to set up a Kubernetes cluster with Raspberry Pi boards: https://blog.hypriot.com/post/setup-kubernetes-raspberry-pi-cluster/. If you need some configuration examples (executable on a Raspberry Pi Kubernetes Cluster) please check out my GitHub repository with configuration examples: https://github.com/MatthiasLohr/kubernetes-rpi-examples.
In How to set up your YubiKey NEO I already mentioned that you can also use your YubiKey as SSH key. In GPG Agent Forwarding I show how to forward your GPG agent to remote machines for decryption/signing. What’s missing is a tutorial on how to make it all work together, how to use your GPG Agent for SSH in Gnome. Read more “GPG Agent for SSH in Gnome”
Windows 10 offers certmgr.msc, a tool for managing the local certificate store. However, Windows 10 also offers a feature to disable the export of the private key (see below). With iSECPartners’ jailbreak (GitHub) you can export it anyway.
Docking stations are quite a pleasant thing, because they save you having to plug in and out a lot of different cables (network, USB, monitors, power,…). Meanwhile, docking solutions via USB-C/Thunderbolt are also available. This means that a single USB cable is all it takes to connect the computer to the peripherals and the power supply. Practically USB-C or Thunderbolt are standards, so you can combine different devices like the HP Elite Thunderbolt Dock with a Lenovo X1 Carbon, right?
Introducing DigitalOcean Spaces
DigitalOcean Spaces is a new product from DigitalOcean, which offers a S3 compatible, flexible storage place for your data – and it’s much simpler to configure compared to Amazon’s S3 or other solutions i know.
Because uploading the whole stuff via a web based interfaces is really annoying, i tried to mount the storage with my Ubuntu Linux. Here’s the result, which may help you to success faster than i did.
Everybody is talking about blockchains. No, they mean Blockchains. Or is it Bitcoin? Where is the difference? Isn’t that all the same?
How to get your mails delivered to Microsoft’s SMTP servers
When setting up a new SMTP server (i needed one for my GitLab instance), sometimes it happens that you get a new IP address which was used before for sending spam mails – or other mysterious things which might end up at the blacklist of (major) email providers – like Microsoft. So i just found this:
<firstname.lastname@example.org>: host outlook-com.olc.protection.outlook.com[188.8.131.52] said: 550 SC-001 (COL004-MC6F4) Unfortunately, messages from aa.bb.cc.dd weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. (in reply to MAIL FROM command)
So… i am my own internet provider, what now?
After some time of searching, i found a list of multiple links to the Mircosoft Delisting Service – and none of them is working, except only one. If you want to save your time when having the same problem – here it is:
After using the form, it may take some time until the request is processed. After processing you will receive a mail from Microsoft with the confirmation or rejection. If successful, it would take up to 24-48 hours to be unblocked from all relevant mail servers.
As far as i know, this applies for outlook.com, live.com and hotmail.com email addresses.
Monitor your IP’s status
Microsoft offers mail server administrators the Smart Network Data Service platform (https://postmaster.live.com/snds/), on which they can register their IP addresses and view the corresponding status, e. g. whether the IP is blocked or not. It is also worth taking a look at the Junk Mail Reporting Program to find out which mails classify users of Microsoft mail services as spam.