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I recently had an issue within the network of a customer who was experiencing a big amount of broadcast, unknown unicast and multicast – short BUM – traffic within one of his layer 2 network segments. My customer is a company which is offering dedicated servers and virtual machines to all sorts of customers and with all sorts of hardware configurations. During the last years, they did not invest much time and money into ther network which is why there are no filters for spoofed/forged traffic and loops in place by now. ...

Due to a software issue on one of our QFX5100 switches, we’ve decided to reinstall the software on the device via the USB reinstallation method. We tried at multiple times to boot the switch from the USB thumb drive without success, even trying multiple different USB thumb drives and different methods to write the installation image onto the switch. The result kept the same: The device showed some cryptic text on the serial interface for a few seconds and then booted once again from the JunOS image residing on the SSDs. ...

Two years ago, I’ve used multiple Intel X710-DA4 NICs to built an EVPN Setup for my company level66.network. Whilst most of the connections to other peers worked quite well, I’ve had a few links which showed some strange issues. Most commonly the links were reported as flapping from the other peers or they just reported packetloss on their end. After quite some time of troubleshooting, switching optics and using different ports we found the solution. With the default configuration of the Linux driver, the NIC seems to sent out some (maybe malformed) LLDP messages causing issues with some specific networking gear. We were not able to narrow it down to a specific vendor, though. These messages are directly generated on the NIC and are therefore not shown in a tcpdump. That’s why we were not aware of them. ...

Some time ago, I built my own Stratux Air Traffic Receiver which I used to show other airplanes on my electronic flight bag. Since a few flights, I am trying the app SafeSky. SafeSky uses multiple datasources from the internet to gather and display other traffic in EFB like ForeFlight and SkyDemon. The app runs on the same device as the navigation software, exporting the data into the local network via messages in the GDL90 format similar to the Stratux. The navigation tools like ForeFlight and SkyDemon are able to decode these messages and to display the traffic information directly on the moving map. ...

During the boot-process of my SG115 appliance with OPNsense I stubled over a issue with the configuration of the BIOS settings of the appliance. During the initialization of USB, the kernel died and moved over to the debug-mode leaving the installation of OPNsense unfinished. usbus0: EHCI version 1.0 usbus0 on ehci0 usbus0: 480Mbps High Speed USB v2.0 isab0: <PCI-ISA bridge> at device 31.0 on pci0 isa0: <ISA bus> on isab0 acpi_button0: <Power Button> on acpi0 acpi_button1: <Sleep Button> on acpi0 acpi_tz0: <Thermal Zone> on acpi0 atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0 atkbd0: <AT Keyboard> irq 1 on atkbdc0 NMI ISA 20, EISA 0 NMI/cpu0 ... going to debugger timeout stopping cpus [ thread pid 0 tid 100000 ] Stopped at send_kbd_command+0x49: movq %r12,%rdi db> While searching through the internet, I stumbeled over a post at reddit of one claiming a similar issue while running pfSense on the SG115 appliance. The trick is to disable the “Port 60/64 Emulation” in the USB settings in the BIOS. Once the emulation is disabled, the boot-process works as desired. ...

I keep forgetting the default-password of the Growatt ShineWiFI-X used to connect the Growatt PV-Inverters to their cloud-service. Therefore I created this blogpost to keep me reminded of the password userd to connect to the Wi-Fi dongle during the first setup. growatt growatt-20221120 (put the current date in there) 12345678 Additionally, a installer code is needed during the registration of the inverter in the app. If you live in germany and are not willing to request a code on your own (by mail to: service.de@growatt.com), you may try this one: AMZXB ...

During the morning of the 8th of November 2022 multiple customers contacted me regarding connectivity issues to services pretty much all across the internet. Once I started digging through the traceroutes and MTRs of customers, I found most of them showing excessive packetloss starting at a hop resolving to “dtag.equinix-fr5.nl-ix.net”. Until that point, I have not even been aware that Deutsche Telekom (AS3320) is connected to NL-ix as they’ve neither listed their presence at PeeringDB… ...

Today, I had a strange issue with IPv6 on my Proxmox VE based Hypervisors. I configured IPv6 for a customer by using a transfer subnet between our gateway router and the virtuel firewall. Additionally, I’ve routed a /56 subnet to be used by the customer onto the firewall and added a few /64s onto the internal interfaces of the customer. Once I configured static addresses on the servers running behind the firewall, they were able to reach the IPv6 internet without any issues. ...

During the last month, our engery supplier installed a digital meter for our power usage at home. As he in addition to that offered to unlock the device or to give us the PIN to unlock it ourselves, I were looking for a solution to extract the data from the meter and push it into our Home Assistant installation. I bought the Volkszähler TTL from eBay and wired it onto the serial interface of an ESP8266 laying around on my desk. The seller shared me two links to YouTube videos (https://youtu.be/RbyXqJiBC8Q, https://youtu.be/VuXpzKetOhc), where he explains how to modify and build the Tasmota firmware to include the SML interface to the power meter. ...

Flying has been always one of my dreams. My aviation career initially started as a small kid when my parents registered me on a holiday-course to build a small model glider (Graupner RC UHU). After roughly one week of crafting, the small model airplane was ready and successfully had its maiden flight on a hill near the village I lived. A few months later, I upgraded it with a kit providing an electric motor and a bigger battery so it could stay in the air even during bad wind conditions. After a few flights even through stronger winds, I accidentally smashed it into the ground and fully destroyed it. ...