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 “Proceed on” button. […]
Chrome Won’t Let You Proceed to Website with Invalid Certificate Read More »
Problem: In syslog you find a line like this: But when you check with “smartctl -a” you find a reallocated sector count of zero: Discussion: The harddisk had actually no reallocated sectors, but Smartctrl (Smartmontools) reported a wrong error, because when it was started a different harddisk with errors was found as /dev/sda, but with
Smartd Reports “Reallocated_Sector_Ct” erroneously Read More »
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 commands into the shell. But
Devuan4/Debian11 usability annoyances Read More »
Every Cisco switch has a serial number that shows information about it’s production location and year. As you see this switch is very old and was running very long. Without any issues btw. The serial number here is shown as “Processor board ID”, you might also find “System serial number” or similar. The format is
Cisco Serial Number Production Date Read More »
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 these helpers are
Linux Connection NAT Helper not Working Read More »
Problem: curl php wget and others show a cert error like the following since 6. Oct 2021, even though the cert has not expired: The asked server uses a Letsencrypt certificate. Discussion: Currently Letsencrypt includes two chains for validation of the certificate: Cert -> R3 -> ISRG Root X1 (in new trust store) Cert ->
Debian Curl/PHP/wget etc show an certificate error falsely Read More »
Admins who prefer a Unix style operation system and don’t like the centralized “one tool doing it all” approach of systemd, switch to Devuan. This mostly improves uptime over boot time. Admins of servers don’t care about boot time and prefer uptime. This list keeps track of the related versions of Devuan and Debian. Debian
Devuan / Debian Versions Read More »
There are at least two pieces of software you can update in a Cisco ASR-1001-X. The ROMMON (firmware) and the IOS itself. This router uses “Cisco IOS XE Software”. Which is an IOS process on a Linux kernel as far as I know. Cisco recommends specific ROMMON releases for different generations of software. You can
Cisco ASR-1001-X Update Read More »
DHCP relaying is used to forward DHCP requests to a DHCP server if the client and the server are not on the same network. One standard implementation of this is isc-dhcp-relay which is part of the isc-dhcp package. Problem: The dhcrelay is forwarding the dhcp request to the dhcp server and the dhcp server is
DHCP Relay on Linux Read More »
After Devuan 3 update ls output showed characters, that are not really in the directory listing. The reason is that “ls” draws quotes around filenames with spaces. This is a bug from my point of view, ls should never change the actual filenames. If a filename has quotes or double quotes it’s even weirder .
LS Style After Devuan 3 or Debian 10 Update Read More »