TL;DR: If you experience poor network performance on your wireless notebook, Microsoft may be using your device as a download server without your consent. Problem: I noticed a high number of requests between Windows clients in different network zones on a customer’s firewall. It appeared that allmost every client was attempting to connect to allmest […]
IP Scan Between Microsoft Clients on Port :7680 ? Read More »
Problem: ssh rejects connecting to old servers with this error: Discussion: After upgrading your client operating system, the new installed openssh-client disabled some old ssh key type and key exchange mechanisms, but you can enable them with command line options or in ssh_config. Solution 1: Add a command line option: Solution 2: Add a line
Reactivate old SSH host key types Read More »
Problem: you find a key and a cert file on, and need to check if the cert matches the key. Solution: Check the modulo (n=p*q) of both key and cert to see if they are equal. Version: tested with openssl 3.0.11 on devuan 5
How to Check If an RSA Cert Matches an RSA Key Read More »
Problem: After upgrading an old HP ProLiant DL320 G6 Server to Linux kernel 6.1 (Devuan 5, Debian12) the system crashes during reboot. You will see the following kernel output: These errors are repeated several times, and the RAID controller driver “hpsa” for the SmartArray Controller P212 gives up, causing /dev/sda vanish. Discussion: While not absolutely
DMAR Kernel Log Errors and RAID Controller Crash Read More »
Problem: when adding a shortcut of a webpage to the Android home screen, Chrome used <link rel=”icon” …> to give this shortcut an icon. Lately Google Chrome broke this feature (intentionally probably). Chrome just shows a grey round circle with a single letter instead of the provided icon. Discussion: Google removed it’s claim “don’t be
Icon Missing When Adding a Webpage to the Android Homepage Read More »
Problem: after upgrading Cisco ISO XE from 15 to 16 on an ASR-1001-X router, the permanent license of this router changes to “evaluation license” and Cisco forces you to use the call-home “feature”. You will find log entries like these: Discussion: Cisco enforces this call-home feature for newer software releases. There is not much you
Cisco “Smart” License Read More »
Problem: Chrome shows an error message like “NET::ERR_SSL_OBSOLETE_VERSION” when connecting to an old device. This might be an old network device or printer or KVM switch oder DRAC/RemoteInside port of servers. Discussion: since Chrome ~98 Google decided that you are not allowed to connect devices that use TLS1.1 and below, only TLS1.2 and above are
Chrome Refuses to Connect to Old Devices Read More »
Problem: You plug in a NodeMCU ESP32 board (from BerryBase in my case) to you computer, but no USB serial port is registered in /dev/. lsusb shows a device called “VeriFone USB to UART Bridge Controller” instead of the expected “CP2102/CP2109 UART Bridge Controller” In this case Ardunio Studio cannot find the module. Solution: thanks
ESP32 Module does not Register as Serial Port Read More »
Problem: After an update of a server to Devuan4/Debian11the switch shuts down the interfaces to the server with status “dcxNoACKi” 48 minutes after the reboot. Discussion: the switch is a Cisco Nexus 5000 switch. It implements “Data Center Bridging Capability Exchange (DCBX)”. The server is a Dell server with X710 Controller 10GbE with i40e drivers.
Interface down on Cisco Nexus switch with “dcxNoACKi” Read More »
Problem: when you switch between Apple Mac and normal keyboards and use German keyboard layout, you can change the keyboard layout on MacOS to “de standard” to have most characters where you would expect them (e.g. @ { } …) but on german keyboards the “AltGr” is located directly right of the space bar. On
Change Right Modifier Keys on MacOS Read More »