Ubuntu: Networking - Docker and KVM on the same box

If you like me have a box which is running everything, like; Docker, kvm and lxc then you probably also once in a while get gray hair from sorting out networking.  So Docker like to control networking and I let it - only exception is that I'm having a separate bridge (macvlan) for everything Docker as it does sometimes makes life easier (not often). But as Docker see everything, even with multiple network cards / bridges as one whole, it does apply it's iptables rules to everything. Which does cause some problems for kvm and lxc.  One easy way to allow communcation to the kvm vm's via your bridge (if you use bridged networking) is to allow it: iptables -A FORWARD -i br0 -o br0 -j ACCEPT Replace 'br0' with what ever you use as bridge for kvm / lxc. To have this to execute automatically everytime you retart networking (reboot the box) create the following file: /etc/systemd/system/restore-iptables-rules.service With this content: [Unit] Description = Apply iptab

MacOS (Catalina): install a fresh xCode 12.4

I'm not in love with Big Sur (far from it - it's plain ugly), and only now upgraded to Catalina. After upgrading I wanted to upgrade xCode to 12.4 (which is the latest version which is supported on Catalina). App Store only want's to install 12.5 which is only supported (install-able) on Big Sur (piece of junk). But I found a way. Install brew ( open follow the instructions on how to install (you might be asked to install xcode-command-line tools - do so). Install 'mas' on the command line, do: brew install mas Install xCode  on the command line, do: mas install xcode - click [download] and it will install xCode 12.4. And there you have, xCode 12.4 is installed.  

Linux: lxc guest does not get an DHCP address using bridge

Title could also be; lxc networking does not work, using a bridge. I use a bridge for all my lxc guests (also for docker). This is so that I do not need to setup iptables forwarding to my guests (easy). But setting up a new Ubuntu 20.04 LTE host gave me some headacke. I could not get my gust to get an ipaddress, and using tcpdump I could see that it did not get an dhcp reply - and looking in the dhcpserver log I could see that nohing arrived there either. Lots of digging aournd for a good two hours (compaing to another Ubuntu 20.04 LTE), and finally I found the differnce. On the box where it was workning I had /etc/sysctl.d/99-sysctl-bridge.conf containg: net.bridge.bridge-nf-call-ip6tables=0 net.bridge.bridge-nf-call-iptables=0 net.bridge.bridge-nf-call-arptables=0   Adding the same file to my problem box, and issuing "sysctl -p /etc/sysctl.d/99-sysctl-bridge.conf", then restaring my lxc guest, and it got an ip address.   What it does is that it disables the firewall on the

MacOS: Disable start of xterm when starting XQuartz

 There are many good references to how to disable the start of xterm when starting XQuartz on MacOS. But as some of us are installing it using (home)brew the preferences file is not the one many are pointing to. Using the (home)brew version of XQuartz the preferences file is org.xquartz.X11.plist, and to disable xterm from auto starting do the forllowing; Start a terminal and type the following: $ defaults write org.xquartz.X11 app_to_run $(which false) To see the result do: $ defaults read org.xquartz.X11 {     SUHasLaunchedBefore = 1;     SULastCheckTime = "2021-04-22 11:33:05 AM +0000";     "app_to_run" = "/usr/bin/false";     "cache_fonts" = 1;     depth = "-1";     "done_xinit_check" = 1;     "enable_fake_buttons" = 0;     "enable_iglx" = 0;     "no_auth" = 0;     "nolisten_tcp" = 1; } Now (re-)start XQuartz and xterm should no longer autostart.

Docker: Connecting to a Remote Host

I for one, maybe not everyone, but I for a long time though that to be able to communicate with a docker instance I had to be on that box. First, after digging around I found the DOCKER_HOST environment variable, which served it purpose, and allowed me to connect to one or more of my docker hosts; $ export DOCKER_HOST="ssh://me@dockerhost $ docker ps CONTAINER ID IMAGE... 1b2e8e4a546a casperghst42/pms-docker... 4de622e79fa6 casperghst42/httpserver... ... Now after (unsuccessly) having looked at VS Code and it's Docker extension (which as of writing is broken in more than one way), I discovered Docker Contexts. Instead of using DOCKER_HOST one should use docker contexts , which allow to setup multiple hosts to connect to. Example: $ docker context ls NAME           TYPE           DESCRIPTION default        moby           Current DOCKER_HOST based dockerhost * moby .... Setting up a new context is quite easy: $ docker context create <contextname> -

Is High-End Hifi a hoax ....

In an youtube video John Darko (could have been this one ) argued that a thing costing 25,000$ is reasonable well priced, if it provide the same as other things which cost around the same. The problem in this, is that will you actually get something which is really at that quality and/or good (to the price), or are you being ripped off. In another video (this one ) John Darko argues that the Allo DigiOne Signature (priced around 500$) is as good as a similar streamer, costing more than 3,000$ - now how does the first (later) comment connect to the first comment. It does not..... Yes the Hifi industry is driving by quality, but price does not have anything to do with it. Remember your iPhone which cost your more than 1,000$ actually only cost around 250$ to produce, then you probably have to take another 25-50$ for the work on the design and so stuff. But when you then hear than Apple earns +10 billion $ a quarter... then it starts to show that someone is paying a lot more for something

EIZO Colornavigator - Data Access Error

The other day I changed the SSD in one of my Macbooks (retina ...), and restored it from a TimeMachine backup. Everything was working, except for Eizo Colornavigator 7, which gave me an error: "Data Access Error - Failed to write data. The data my be corrupted. Uninstall ColorNavigator 7 once and reinstall it" If for the life of it couldn't figure out what was going on, even using AppCleaner (which normally does a proper cleanup) did not fix it. I removed everything else I could find which had to do with Eizo, and still problem was there. I then contacted Eizo Support, which told me to reinstall ... dooo..... But I then just for the fun of it install the latest version again, and look at what it installed, and found "/Library/Application Support/EIZO/tools/ColorNavigator 7/" which have Uninstaller” and "ColorNavigator 7”. So the fix is: # cd  "/Library/Application Support/EIZO/ColorNavigator 7/tools” # open “ColorNavigator 7 Un