Linux Containers: Configuring Network Address (part 636)

 Computing, Linux, Working Notes  3 Responses »
Jun 052019
 

On previous occasions (yes that does mean more than once) I have messed around with the network configuration of containers to get :-

  1. A consistent behaviour.
  2. A fixed IPv4 address with no DHCP configuration (this one is easy).
  3. A fixed IPv6 address with no autoconfigured global addresses (this one has been tricky)

This turns out to be relatively easy providing that you configure the addresses within the container rather than within the container configuration. At least it looks good to go so far (I’ve been mistaken in the past).

The container configuration is quite simple :-

lxc.net.0.type = veth
lxc.net.0.flags = down
lxc.net.0.link = br0

Note that the bridge interface (br0) may be different. Also note that there is no lxc.net.0.ipv4.address, lxc.net.0.ipv4.gateway, lxc.net.0.ipv6.address, or lxc.net.0.ipv6.gateway.

The configuration within the container is dependent on what userland you are running, but for Debian (and Ubuntu if you’re not using Netplan) :-

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
    address 10.0.0.34/16
    gateway 10.0.0.1

iface eth0 inet6 static
    address 2001:0db8:cafe:dead:0000:0000:0000:3eb/64
    scope global
    gateway 2001:0db8:cafe:dead:0000:0000:0000:0001
    privext 0
    accept_ra 0
    autoconf 0

Not sure quite which options are required but having all of “privext 0”, “accept_ra 0” and “autoconf 0” does mean no additional autoconfigured IPv6 addresses.

(And no the part number of this post isn’t anything more than a joke)

Silly Tools for The Graphical Terminal: Flag

 Computing, Linux  No Responses »
Jan 252019
 

If you are using the right kind of terminal that supports graphics inline (such as KiTTY), then you can write simple (or complex) tools that insert images into the terminal.

Being able to display the flag of a country (if you know its two-letter ISO code) is kind of trivial but useful if you need it.

And a shell function to do that is remarkably simple :-

function flag {
    wget -o /dev/null -O /var/tmp/flag.$$ http://flagpedia.net/data/flags/normal/${1}.png
    if [ $? -eq 0 ]
    then
        kitty +kitten icat /var/tmp/flag.$$ && rm /var/tmp/flag.$$
    else
        echo Not found
    fi
}

(that’s a Zsh function which may require adaption to Bash).

Why Does Tilde (~) Mean Home In Linux?

 Computing, History  No Responses »
Nov 112018
 

If you use the Unix or Linux command-line, you may very well wonder about the origins of some of the “special” characters. One of those is tilde (~) which is expanded by the shell into “home” :-

✓ mike@Michelin» echo $HOME                        
/home/mike
✓ mike@Michelin» echo ~
/home/mike
✓ mike@Michelin» echo ~root
/root

This doesn’t of course work in general; just in the shell.

But where did this usage originate?

As it turns out, it was the markings on the keyboard of the ADM3A terminal :-

If you used Unix in the late 1970s/1980s, you may very well have used the ADM3A terminal and it seems that those who added the tilde feature to the Unix shell were amongst the users.

Steam on Linux

 Computing, Linux  No Responses »
Sep 102018
 

If you have not heard, Steam have added a compatibility layer to Steam which allows a limited number of Windows games to run. The “compatibility layer” is in fact a fork of WINE called Proton.

Peered at from 500 metres away, Proton allows Windows software to run (or not infrequently crash and burn) by translating the Win32 API into Linux APIs, and translating the variety of graphics APIs into Vulkan. That is a really difficult thing to do.

I have taken a very quick look at the new Steam client (and “Proton” is no longer part of a beta release of the Steam client – it’s in the standard client). It works perfectly adequately, although you will have variable experiences running Windows software.

For some reason this news has captured the imagination of a number of ‘tubers who are more gamers than Linux users, which has lead to some misunderstanding :-

  1. This is not Linux gaming; it is Windows gaming under Linux. If you have a bad experience with Steam under Linux, you are not experiencing a bad time with Linux gaming. Linux gaming involves native Linux software, and yes there is some out there.
  2. Problems with Steam could well be down to the Proton compatibility layer with unsupported API calls or buggy usage of the Win32 API which relies on Windows behaving in a certain way for undefined parameters.
  3. In addition problems with Steam could be due to the hardware you are running; take a game that works perfectly fine with an Nvidia card. It may behave problematically with an AMD card or even a different Nvidia card. Or the other way around.

The important thing to remember when looking at videos about Steam is that the person looking at Steam may not be the most experienced Linux user out there. That is not necessarily bad – the whole purpose of Steam is to be able to run games easily without a whole lot of Linux experience.

But they may not be understanding properly what is going on – for example the first thing I would do as a professional game-orientated ‘tuber would be to try out a selection of games with an nvidia card, and then repeat using an AMD card – just to see if things work better, worse, or at least differently.

And again, this is not about Linux gaming but about allowing easy access to old Windows titles that someone may have bought in the past. 

Pentland Hills

Linux: No You Don’t Need The Command-Line, But It Isn’t That Scary

 Computing, Linux  No Responses »
Sep 082018
 

Having used Linux for well over 20 years (yes it is that old), and Unix before that, I’m often puzzled by how scary some people seem to find Linux. Why should it be scary? It’s just a computer – you’re the human in charge of it.

Yes There Are Gooeys

(graphical user interfaces – GUIs – gooeys)

Yes there is plenty of software with a graphical user interface – I use plenty on a daily basis including a standard web browser, an email client, a password manager, an office package.

On a slightly less frequent basis there are many more that I use. Indeed providing that you accept the use of alternatives, you can find Linux software to do just about anything.

But Don’t Ignore The Command-Line

Yes, Linux has a command-line, and for those of us familiar with it, it can be very powerful. And there is no harm in learning how to use the command-line just to the point where you can follow instructions on how to “get something done” there.

Because if I have a fix for some niggle that you are having, it is easier and less error-prone to pass instructions for a command-line incantation than instructions for a gooey (and yes I have done both).

The Birds

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