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squashing old git history

You may have an internal project that you wish to open source. When starting the project, you didn’t take that into account, so it’s likely to contain references to private data that you do not wish to share. Step one would be to clean things up. If this is a slow process, this can take time, while in the mean time the project gets updates. Now, at one point you’re confident that at commit X1000, the project contains only non-private data.

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Loadbalancer maintenance 22nd february 2017

In the night of Wednesday (22nd of Febr. 2017) to Thursday (23rd of Febr. 2017) between 23:45 and 03:00 we will perform maintenance on our loadbalancers. ####Maintenance window 22-02-2017 23:45 - 23-02-2017 03:00 ####Description Loadbalancers will be upgraded to increase throughput and enable new capabilities. ####Impact When maintenance starts, we’ll reroute all traffic to the secondary loadbalancer. Customers that have a multi-site setup should therefore not have any service interruption.

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detect invisible selection / copy buffer / chrome

In Look before you paste from a website to terminal the author rightly warns us about carelessly pasting any input from a web page into the terminal. This LookBeforePaste Chrome Extension is a quick attempt at trying to warn the user. Example output when pressing CTRL-C on the malicious code: Heuristics are defined as follows. They could certainly be improved, but it’s a start. function isSuspicious(node) { if (node.nodeType == node.

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convert / dehydrated / certbot / letsencrypt config

If you find yourself in the situation that you have to reuse your Letsencrypt credentials/account generated by Dehydrated (a bash Letsencrypt interface) with the official Certbot client, like me, you’ll want to convert your config files. In my case, I wanted to change my e-mail address, and the Dehydrated client offered no such command. With Certbot you can do this: $ certbot register --update-registration --account f65c... But you’ll need your credentials in a format that Certbot groks.

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mysql / deterministic / reads sql data

Can I use the MySQL function characteristic DETERMINISTIC in combination with READS SQL DATA and do I want to? TL;DR If the following two groups of statements are the same to you, you want the DETERMINISTIC characteristic on your FUNCTION, even if you have READS SQL DATA. SET @id = (SELECT my_func()); SELECT * FROM my_large_table WHERE id = @id; -- versus SELECT * FROM my_large_table WHERE id = my_func(); (All of this is tested with MySQL 5.

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Availability during holiday December 2016

Starting the 17th of December we are on leave. We return to the office on the 2nd of January. During this period we are available 24/7 for incident response and other urgent matters as usual. If you already know of any urgent requests which needs to be handled during this period, please inform us in advance so we can plan the required availability.

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patch-a-day / pdns-recursor / broken edns lookups

Last month, our e-mail exchange (Postfix) started having trouble delivering mail to certain destinations. These destinations all appeared to be using Microsoft Office 365 for their e-mail. What was wrong? Who was to blame? And how to fix it? The problem appeared like this: Nov 16 17:04:08 mail postfix/smtp[13330]: warning: no MX host for umcg.nl has a valid address record Nov 16 17:04:08 mail postfix/smtp[13330]: 1D1D21422C2: to=<-EMAIL-@umcg.nl>, relay=none, delay=2257, delays=2256/0.02/0.52/0, dsn=4.

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patch-a-day / dovecot / broken mime parts / xenial

At times, Dovecot started spewing messages into dovecot.log about a corrupted index cache file because of “Broken MIME parts”. This happened on Ubuntu/Xenial with dovecot_2.2.22-1ubuntu2.2: imap: Error: Corrupted index cache file dovecot.index.cache: Broken MIME parts for mail UID 33928 in mailbox INBOX: Cached MIME parts don't match message during parsing: Cached header size mismatch (parts=4100...) imap: Error: unlink(dovecot.index.cache) failed: No such file or directory (in mail-cache.c:28) imap: Error: Corrupted index cache file dovecot.

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tmpfs files not found / systemd

While debugging a problem with EDNS records, I wanted to get some cache info from the PowerDNS pdns-recursor. rec_control dump-cache should supply it, but I did not see it. # rec_control dump-cache out.txt Error opening dump file for writing: Permission denied Doh, it’s running as the pdns user. Let’s write in /tmp. # rec_control dump-cache /tmp/out.txt dumped 42053 records # less /tmp/out.txt /tmp/out.txt: No such file or directory Wait what? No files?

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mysql sys schema / mysqldump failure

After upgrading the mysql-server to 5.7 and enabling GTIDs, the mysql-backup script started spewing errors. Warning: A partial dump from a server that has GTIDs will by default include the GTIDs of all transactions, even those that changed suppressed parts of the database. If you don't want to restore GTIDs, pass --set-gtid-purged=OFF. To make a complete dump, pass --all-databases --triggers --routines --events. (...repeated for every database schema...) mysqldump: Couldn't execute 'SHOW FIELDS FROM `host_summary`': View 'sys.

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copy-pasting into java applications / x11

The other day I was rebooting our development server. It has full disk encryption, and the password for it has to be specified at boot time, long before it has network access. Even though the machine is in the same building, walking over there is obviously not an option. The machine has IPMI, like all modern machines do, so we can connect a virtual console over the local network. For that, we use the SuperMicro ipmiview tool.

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packaging supermicro ipmiview / debian

Do you want to quickly deploy SuperMicro ipmiview on your desktop? IPMI is a specification for monitoring and management of computer hardware. Usually this is used for accessing servers in a data center when the regular remote login is not available. Think: hard rebooting a stuck machine, specifying the full disk encryption password at boot time, logging onto a machine where the remote login (ssh daemon) has disappeared. The SuperMicro IPMI devices have an embedded webserver, but it requires Java to access the console.

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golang / statically linked

So, Go binaries are supposed to be statically linked. That’s nice if you run inside cut-down environments where not even libc is available. But sometimes they use shared libraries anyway? TL;DR: Use CGO_ENABLED=0 or -tags netgo to create a static executable. Take this example: $ go version go version go1.6.2 linux/amd64 $ go build gocollect.go $ file gocollect gocollect: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, \ interpreter /lib64/ld-linux-x86-64.

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sipp / travis / osx build / openssl

A couple of days ago our SIPp Travis CI builds started failing due to missing OpenSSL include files. Between SIPp build 196 and SIPp build 215 the OSX builds on Travis started failing with the following configure error: checking openssl/bio.h usability... no checking openssl/bio.h presence... no checking for openssl/bio.h... no configure: error: <openssl/bio.h> header missing It turns out that something had changed in the build environment and OpenSSL headers and libraries were no longer reachable.

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lxc / create image / debian squeeze

I’m quite happy with our LXC environment on which I’ve got various Debian and Ubuntu build VMs so I can package backports and other fixes into nice .deb packages. Today I needed an old Debian/Squeeze machine to build backports on. Step one: check the lists. $ lxc remote list +-----------------+--------------------------+---------------+-----+-----+ | NAME | URL | PROTOCOL | PUB | STC | +-----------------+--------------------------+---------------+-----+-----+ | images | https://images.linuxco...| simplestreams | YES | NO | +-----------------+--------------------------+---------------+-----+-----+ | local (default) | unix:// | lxd | NO | YES | +-----------------+--------------------------+---------------+-----+-----+ | ubuntu | https://cloud-images.

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Planned maintenance 22 August 2016

In the night of Monday (August. 22nd) to Tuesday (August. 23rd) between 23:45 and 06:00 we will perform network maintenance on our core network. ####Maintenance window Monday (August. 22nd) to Tuesday (August. 23rd) between 23:45 and 06:00 (CEST) ####Description One of the core routers (CR2) at TCN will be relocated to a new rack to allow further expansion on this site and make some desired improvements in the meantime. Impact During the maintenance, routing will be adjusted to free CR2 of traffic.

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HTTP_PROXY "httpoxy" vulnerability (Dutch)

Een stukje uitleg over de HTTP_PROXY vulnerability die op https://httpoxy.org/ gemeld is. Je site is vulnerable indien aan de volgende criteria wordt voldaan: Je hebt een webapplicatie die zelf webaanroepen doet; bijvoorbeeld communicatie met een payment provider of interne backend (d.m.v. python-requests, curl, http_get, etc…). De webserver laat de Proxy header door als HTTP_PROXY. Dit is standaard zo. De HTTP_PROXY header komt tussen de environment variabelen. Dit is niet zo onder bijvoorbeeld python met uwsgi, maar wel bij CGI applicaties en ook bij php-fpm en apache-mod_php!

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Planned maintenance 21 July 2016 [UPDATED]

In the night of Thursday (Jul. 21st) to Friday (Jul. 22nd) between 23:00 and 04:00 we will perform network maintenance on our core network. ####Maintenance window Thursday (Jul. 21st) to Friday (Jul. 22nd) between 23:00 and 04:00 (CEST) ####Description Extra network capacity on our core network will be deployed and tested. During the maintenance, routing will be adjusted to free the links affected of any traffic. Impact No impact expected. Increased chance for short service disruptions due to changes in network.

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letsencrypt / license update / show differences

This morning, Let’s Encrypt e-mailed me that the Subscriber Agreement was updated; but it had no diff. Let’s Encrypt Subscriber, We’re writing to let you know that we are updating the Let’s Encrypt Subscriber Agreement, effective August 1, 2016. You can find the updated agreement (v1.1.1) as well as the current agreement (v1.0.1) in the “Let’s Encrypt Subscriber Agreement” section of the following page: https://letsencrypt.org/repository/ Thank you for helping to secure the Web by using Let’s Encrypt.

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Planned maintenance 17 June 2016

In the night of Friday (Jun. 17th) to Saturday (Jun. 18th) between 23:00 and 4:00 we will perform network maintenance on our core network. ####Maintenance window Friday (Jun. 17th 2016) to Saturday (Jun. 18th 2016) between 23:00 and 4:00. ####Description Extra network capacity on our core network will be deployed and tested. During the maintenance routing will be adjusted to allow active maintenance on certain fiber paths. Impact No impact expected.

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apt / insufficiently signed / weak digest

When adding our own apt repository to a new Ubuntu/Xenial machine, I got a “insufficiently signed (weak digest)” error. # apt-get update ... W: gpgv:/var/lib/apt/lists/partial/ppa.osso.nl_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 4D1...0F5 (weak digest) Confirmed it with gpgv. # gpgv --keyring /etc/apt/trusted.gpg \ /var/lib/apt/lists/ppa.osso.nl_ubuntu_dists_xenial_InRelease gpgv: Signature made Wed 23 Mar 2016 10:14:48 AM UTC using RSA key ID B36530F5 gpgv: Good signature from "PPA-OSSO-NL <support+ppa@osso.nl>" # gpgv --weak-digest sha1 --verbose --keyring /etc/apt/trusted.

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lxcfs - proc uptime

When removing the excess LXC and LXD package from the LXC guest and working around Ubuntu/Xenial reboot issues I noticed the lxcfs mounts on my LXC guest. (No, you don’t need the lxcfs package on the guest.) guest# mount | grep lxc lxcfs on /proc/cpuinfo type fuse.lxcfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) lxcfs on /proc/diskstats type fuse.lxcfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) lxcfs on /proc/meminfo type fuse.lxcfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) lxcfs on /proc/stat type fuse.lxcfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) lxcfs on /proc/swaps type fuse.

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lxc - ubuntu xenial - reboot

The current Ubuntu/Xenial guest image on our new LXD container host contained too many packages. It held the lxd package and a bunch of lxc packages. They are not needed on the container guest. At some point before or after removing them, for some reason the ZFS container got unmounted. This went unnoticed until I tried a reboot: guest# reboot lxd# lxc exec guest /bin/bash error: Container is not running. lxd# lxc start guest error: Error calling 'lxd forkstart guest /var/lib/lxd/containers /var/log/lxd/guest/lxc.

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renaming / lxd managed lxc container

Renaming an LXD managed LXC container is not straight forward. But if you want to rename the host from inside the container, you should do so on the outside as well. If you don’t, you may notice that for instance the DHCP manual IP address assignment doesn’t work as expected. Creating a new LXC container For example, we’ll create a new container called walter-old with a fresh Debian/Jessie on it.

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missing sofiles / linker / asterisk / pjsip

When compiling Asterisk with a PJProject debianized using the debian/ directory to Ubuntu/Trusty, I got the following compile error: $ gcc -o chan_pjsip.so -pthread -shared -Wl,--version-script,chan_pjsip.exports,--warn-common \ chan_pjsip.o pjsip/dialplan_functions.o -lpjsua2 -lstdc++ -lpjsua -lpjsip-ua \ -lpjsip-simple -lpjsip -lpjmedia-codec -lpjmedia-videodev -lpjmedia-audiodev \ -lpjmedia -lpjnath -lpjlib-util -lsrtp -lpj -lm -lrt -lpthread \ -lSDL2 -lavformat -lavcodec -lswscale -lavutil -lv4l2 -lopencore-amrnb \ -lopencore-amrwb /usr/bin/ld: cannot find -lSDL2 /usr/bin/ld: cannot find -lavformat /usr/bin/ld: cannot find -lavcodec /usr/bin/ld: cannot find -lswscale /usr/bin/ld: cannot find -lavutil /usr/bin/ld: cannot find -lv4l2 /usr/bin/ld: cannot find -lopencore-amrnb /usr/bin/ld: cannot find -lopencore-amrwb collect2: error: ld returned 1 exit status That’s odd.

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