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.
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.
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.
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.
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.
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.
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!
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.
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.
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.
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 <email@example.com>" # gpgv --weak-digest sha1 --verbose --keyring /etc/apt/trusted.
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.
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.
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.
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.
CVE-2015-7547: glibc getaddrinfo stack-based buffer overflow
On February 16, 2016 details on a vulnerability in glibc were released (CVE-2015-7547). The vulnerability is remotely exploitable and affects a lot of systems. More info will be added later when more information is available. We started emergency patch procedures for our environments and managed customer environments. Summary Classification: Critical. Remote exploitation possible. Impact: Wide impact, all services that use glibc and perform dns resolving are vulnerable. upstream description The glibc DNS client side resolver is vulnerable to a stack-based buffer overflow when the getaddrinfo() library function is used.
python / xinetd / virtualenv
So, while developing a server application for a client, my colleague Harm decided it would be a waste of our programming time to add TCP server code. Inetd and friends can do that really well. The amount of new connects to the server would be minimal, so the overhead of spawning a new Python process for every connect was negligible. Using xinetd as an inetd server wrapper is simple. The config would look basically like this:
Planned maintenance 13 Feb 2016
In the night of Friday (Feb. 12th) to Saturday (Feb. 13th) between 1:00 and 2:00 our co-location provider will perform maintenance on the PDU’s in one of our racks. Customers we consider to be directly affected (bare metal servers) will receive an additional notification. Outside of that it’s mostly OSSO infrastructure services that are affected. ####Maintenance window 01:00-02:00 on 13th of Februari 2016. ####Description The PDU’s of one of the racks will be taken into service one by one (A and B feed).
salt master losing children
I recently set up psdiff on a few of my servers as a basic means to monitor process activity. It disclosed that my SaltStack master daemon — which I’m running as a non-privileged user — was losing a single child, exactly 24 hours after I had ran salt commands. This seemed to be a recurring phenomenon. The salt server — version 0.17.5+ds-1 on Ubuntu Trusty — was running these processes:
Polyglot XHTML: Serving pages that are valid HTML and valid XML at the same time. A number of documents have been written on the subject, which I shall not repeat here. My summary: HTML5 is not going away. XHTML pages validate in the browser. If you can get better validation during the development of your website, then you’ll save yourself time and headaches. Thus, for your development environment, you’ll set the equivalent of this:
Availability during holiday december 2015
From 24th of December we are on leave and return to the office on the 4th 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.
Planned maintenance - router upgrade RUG RH POP (01:00-04:00 8 DEC 2015)
In the night of Monday (Dec. 7th) to Tuesday (Dec. 8th) between 1:00 and 6:00 we will upgrade the router at our RUG Rekenhal POP. Impact is limited to IP Access locations and IP Transit customers on this POP. ####Maintenance window 01:00-04:00 on 8th of December 2015. ####Description We will upgrade the router to allow planned network upgrades. Impact The router at the RUG Rekenhal POP will be unavailable for 30min-60min.
asterisk / editline / key bindings
Getting the Asterisk PBX CLI to work more like you’re used to from the (readline) bash shell can, be a time-saver. For example, you may want reverse-i-search (^R), backward word deletion (^W) and word skipping (^<arrow-left> and ^<arrow-right>). It can be done, but you must configure the editline library in a similar manner as you would configure .inputrc. Support for the .editrc configuration file was added in May 2011 (git commit d508a921).
Planned maintenance virtual servers TCN (01:00-06:00 27 NOV 2015)
In the night of Thursday (Nov. 26th) to Friday (Nov. 27th) between 1:00 and 6:00 we will perform maintenance to the virtual server infrastructure at location TCN. ####Maintenance window 01:00-06:00 on 27th of November 2015 ####Description Virtual server infrastructure will be upgraded to a new major software release. Due to the major version upgrade and incompatibility between versions servers will experience downtime for 15-60 minutes Impact Virtual servers will be offline for ~15 minutes (up to 60 minutes worst case).
encfs / recursion into itself
We wanted to use EncFS to be able to store encrypted backups. The requirements for that are: The backup server initiates the backup. That’s where we configure which hours are safe (resource wise) and which files need backing up (etc, home, root, srv, …). And it means the backup server can safely be placed behind a gateway disallowing all incoming connections. The backup server cannot know the passwords of files.