Cups PDF Filter Crashes

Problem: for some PDF files cups does not print the page, the web gui just tells “filter failed” and in the cups logfile you find [Job 528] PID 19521 (gs) crashed on signal 11! Discussion: cups on debian uses ghostscript as pdf renderer. The pdf renderer of ghostsciprt crashes on many files. You can test by simply running …

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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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Google Maps Marker on Mobile

Problem: A responsive webapp shows a google map with markers that are clickable. On desktop everything works as expected, but on mobile the markers are not clickable. Discussion: After debugging with chrome remote inspector, I found that a div->frame with opacity:0 was lying above (explicit z-index:2) the clickable markers. I don’t know what this frame is for, …

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F5 Drops WebSockets

Problem: F5 LTM is used als load balancer for multiple web servers. When the client opens a websocket connection to the web server, the connection is closed. Discussion: F5 LTM version before 11.6.0 has a bug in the request_log module (profile). The “request_log” module crashes and drops the connection. The bug is a known issue: https://support.f5.com/kb/en-us/solutions/public/16000/600/sol16690.html Solution: If you …

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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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ASR Tips’n’Tricks

ASR-1001-X and IOS-XE is sometimes different and sometimes very similar to classic IOS. Update. You can update, the firmware as usual: # copy http: bootflash: # conf t (config)# boot system flash bootflash:asr1001x-universalk9.03.16.00.S.155-3.S-ext.SPA.bin Show SFP (transceiver) info: # show hw-module interface tenGigabitEthernet 0/0/0 transceiver status # show hw-module interface tenGigabitEthernet 0/0/0 transceiver idprom .. to be continued