Recent posts (paged)
ESP32 Module does not Register as Serial Port
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" # lsusb Bus 005 Device 008: ID 11ca:0204 VeriFone ...
Interface down on Cisco Nexus switch with "dcxNoACKi"
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 C...
Change Right Modifier Keys on MacOS
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 MacOS th...
Windows / Linux Timezone Settings
Problem: if you have Windows and Linux on the same computer, windows shows the wrong time shifted by your timezone (dst) after rebooting from Linux. Discussion: Linux stores UTC in the computers hardware clock usually. This makes multi user, multi timezone, and dst handling easy, because it knows hardware clock is a...
Devuan Update Fails with Signature Invalid
Problem: (5. September 2022) when fetching Devuan updates you get the following error: Err http://deb.devuan.org/merged beowulf InRelease The following signatures were invalid: EXPKEYSIG BB23C00C61FC752C Devuan Repository (Amprolla3 on Nemesis) repository@devuan.org Discussion: The devuan key to sign the repository ...
Chrome Won't Let You Proceed to Website with Invalid Certificate
As an IT professional it's quite common that have to connect web servers with invalid certificates, for different reasons. For expample opening a management GUI of an appliance may be necessary to change its own certificate or TLS settings. Problem: sometimes chrome won't let you open this website, and gives you no ...
Smartd Reports "Reallocated_Sector_Ct" erroneously
Problem: In syslog you find a line like this: smartd[1514]: Device: /dev/sda [SAT], Failed SMART usage Attribute: 5 Reallocated_Sector_Ct. But when you check with "smartctl -a" you find a reallocated sector count of zero: # smartctl -a /dev/sda ... ID# ATTRIBUTE_NAME FLAG TYPE UPDATED WHEN_FAILED RAW_VALUE 5...
Devuan4/Debian11 usability annoyances
Problem: When pasting commandos to the shell, the shell no longer executes the command but shows the pasted text highlighted and shows the line feed but does not process it. Discussion: Devuan4 and Debian11 upgraded the readline library with a new default "feature" that should prevent noobs from accidentally pasting...
Cisco Serial Number Production Date
Every Cisco switch has a serial number that shows information about it's production location and year. SW# show version Cisco IOS Software, C3560 Software (C3560-IPBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1) Copyright (c) 1986-2007 by Cisco Systems, Inc. Compiled Thu 19-Jul-07 18:15 by nachen Image text-bas...
Linux Connection NAT Helper not Working
Some protocols need more than one TCP or UDP connection. For NAT to work the firewall needs to open additional ports to allow client server connection automatically. Examples are FTP (port 21 handshake, additional ports for data), PPTP (port 1723 for handshake, proto GRE 47 for payload) Since Linux kernel (~) 4.7 th...