Rare Connection Resets after Linux Upgrade

Problem: after upgrading from Debian 6 to Debian 8 some of the machines lose their ethernet network connection under heavy load for some seconds rarely. You find lines like these in syslog: [2333099.217735] NETDEV WATCHDOG: eth1 (tg3): transmit queue 0 timed out [2333099.217966] tg3 0000:03:04.1 eth1: transmit timed out, resetting [2333099.384391] tg3 0000:03:04.1 eth1: 0: Host …

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Compiling Sendmail on Debian7

Problem: after compiling sendmail on Debian7 with “./Build” sendmail does not recognize hash .db files. You see the following error message: readcf: map access: class hash not available Discussion: ./Build should detect the berkley DB automatically. When devtools/bin/configure.sh finds libdb.so it adds -DNEWDB as compile option. On Debian7 the libdb.so file moved to /usr/lib/x86_64-linux-gnu/ and configure.sh fails to …

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Generate CSR using openssl

Browsers started to warn users about certificates with Sha1 signature. Sha256 is needed now a days. So it’s time to renew certificates from Thawte, Godaddy, etc You can generate a new Certificate Signing Request with openssl with this command: openssl req -nodes -newkey rsa:2048 -keyout servername.key -out servername.csr -sha256 “servername.csr” is an ascii file you can send …

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Debian 8 Uses only One Core of a Multi Core CPU

Problem: A fresh installed Debian 8 (Jessie) 32bit 686 uses only one core of a 6 core Xeon CPU. amd64 kernels don’t have this problem. Solution: The HP Proliant DL360 Gen9 has a BIOS option called “Processor x2APIC Support”. When you set this option to “Disabled” the Linux kernel uses all 6 cores. x2APIC is a …

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Openbox goes weird with R.A.T.5 Mad Catz

Problem: when you connect the Mad Catz R.A.T.5 mouse to a Linux box running openbox window manager, the window handling stops working. Sometimes mouse follow focus does not work, sometimes even  clicking a window cannot activate it. Sometimes clicking window borders does not work, sometimes clicking into windows is ignored. Solution: This mouse has a mode button, which is …

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USB SCSI Disconnects when Idle

Problem: An external USB harddrive disconnects and immediately reconnects with different device name. You find log entries like these: Jan 17 00:46:52 workstation kernel: [212306.086568] sd 33:0:0:0: [sdj] Attached SCSI disk Jan 17 01:51:14 workstation kernel: [216168.064075] usb 2-4: USB disconnect, device number 11 Jan 17 01:51:15 workstation kernel: [216168.596514] usb 2-4: new SuperSpeed USB device …

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