Tag: Open Source

"Submarine" by "NH53" on Flickr

Recursive Git Submodules

JonTheNiceGuy Leave a comment

One of my colleagues asked today about using recursive git submodules. First, let’s quickly drill into what a Submodule is.

Git Submodules

A submodule is a separate git repository, attached to the git repository you’re working on via two “touch points” – a file in the root directory called .gitmodules, and, when checked out, the HEAD file in the .git directory.

When you clone a repository with a submodule attached, it creates the directory the submodule will be cloned into, but leave it empty, unless you either do git submodule update --init --recursive or, when you clone the repository initially, you can ask it to pull any recursive submodules, like this git clone https://your.vcs.example.org/someorg/somerepo.git --recursive.

Git stores the commit reference of the submodule (via a file in .git/modules/$SUBMODULE_NAME/HEAD which contains the commit reference). If you change a file in that submodule, it marks the path of the submodule as “dirty” (because you have an uncommitted change), and if you either commit that change, or pull an updated commit from the source repository, then it will mark the path of the submodule as having changed.

In other words, you can track two separate but linked parts of your code in the same tree, working on each in turn, and without impacting each other code base.

I’ve used this, mostly with Ansible playbooks, where I’ve consumed someone else’s role, like this:

My_Project
|
+- Roles
|  |
|  +- <SUBMODULE> someorg.some_role
|  +- <SUBMODULE> anotherorg.another_role
+- inventory
+- playbook.yml
+- .git
|  |
|  +- HEAD
|  +- modules
|  +- etc
+- .gitmodules

In .gitmodules the file looks like this:

[submodule "module1"]
 path = module1
 url = https://your.vcs.example.org/someorg/module1.git

Once you’ve checked out this submodule, you can do any normal operations in this submodule, like pulls, pushes, commits, tags, etc.

So, what happens when you want to nest this stuff?

Nesting Submodule Recursion

So, my colleague wanted to have files in three layers of directories. In this instance, I’ve simulated this by creating three directories, root, module1 and module2. Typically these would be pulled from their respective Git Service paths, like GitHub or GitLab, but here I’m just using everything on my local file system. Where, in the following screen shot, you see /tmp/ you could easily replace that with https://your.vcs.example.org/someorg/.

The output of running mkdir {root,module1,module2} ; cd root ; git init ; cd ../module1 ; git init ; cd ../module2 ; git init ; touch README.md ; git add README.md ; git commit -m 'Added README.md' ; cd ../module1 ; git submodule add /tmp/module2 module2 ; git commit -m 'Added module2' ; cd ../root ; git submodule add /tmp/module1 module1 ; git submodule update --init --recursive ; tree showing the resulting tree of submodules under the root directory.
The output of running mkdir {root,module1,module2} ; cd root ; git init ; cd ../module1 ; git init ; cd ../module2 ; git init ; touch README.md ; git add README.md ; git commit -m ‘Added README.md’ ; cd ../module1 ; git submodule add /tmp/module2 module2 ; git commit -m ‘Added module2’ ; cd ../root ; git submodule add /tmp/module1 module1 ; git submodule update –init –recursive ; tree showing the resulting tree of submodules under the root directory.

So, here, we’ve created these three paths (basically to initiate the repositories), added a basic commit to the furthest submodule (module2), then done a submodule add into the next furthest submodule (module1) and finally added that into the root tree.

Note, however, when you perform the submodule add it doesn’t automatically clone any submodules, and if you were to, from another machine, perform git clone https://your.vcs.example.org/someorg/root.git you wouldn’t get any of the submodules (neither module1 nor module2) without adding either --recursive to the clone command (like this: git clone --recursive https://your.vcs.example.org/someorg/root.git), or by running the follow-up command git submodule update --init --recursive.

Oh, and if any of these submodules are updated? You need to go in and pull those updates, and then commit that change, like this!

The workflow of pulling updates for each of the submodules, with git add, git commit, and git pull, also noting that when a module has been changed, it shows as having “new commits”.
And here we have the finish of the workflow, updating the other submodules. Note that some of these steps (probably the ones in the earlier image) are likely to have been performed by some other developer on another system, so having all the updates on one machine is pretty rare!

The only thing which isn’t in these submodules is if you’ve done a git clone of the root repo (using the terms from the above screen images), the submodules won’t be using the “master” branch (or a particular “tag” or “branch hame”, for that matter), but will instead be using the commit reference. If you wanted to switch to a specific branch or tag, then you’d need to issue the command git checkout some_remote/some_branch or git checkout master instead of (in the above screen captures) git pull.

If you have any questions or issues with this post, please either add a comment, or contact me via one of the methods at the top or side of this page!

Featured image is “Submarine” by “NH53” on Flickr and is released under a CC-BY license.

"$bash" by "Andrew Mager" on Flickr

One to read: Put your bash code in functions

JonTheNiceGuy Leave a comment

I’ve got a few mildly ropey bash scripts which I could do with making a bit more resilient, and perhaps even operating faster ;)

As such, I found this page really interesting: https://ricardoanderegg.com/posts/bash_wrap_functions/

In it, Ricardo introduces me to two things which are interesting.

  1. Using the wait command literally waits for all the backgrounded tasks to finish.
  2. Running bash commands like this: function1 & function2 & function3 should run all three processes in parallel. To be honest, I’d always usually do it like this:
    function1 &
    function2 &
    function3 &

The other thing which Ricardo links to is a page suggesting that if you’re downloading a bash script and executing it (which, you know, probably isn’t a good idea at the best of times), then wrapping it in a function, like this:

#!/bin/bash

function main() {
  echo "Some function"
}

main

This means that the bash scripting engine needs to download and parse all the functions before it can run the script. As a result, you’re less likely to get a broken run of your script, because imagine it only got as far as:

#!/bin/bash
echo "Some fun

Then it wouldn’t have terminated the echo command (as an example)…

Anyway, some great tricks here! Love it!

Featured image is “$bash” by “Andrew Mager” on Flickr and is released under a CC-BY-SA license.

A screenshot of the Wordpress site, showing updates available

wp-upgrade.sh – A simple tool to update and upgrade WordPress components via cron

JonTheNiceGuy Leave a comment

A simple tool to update and upgrade WordPress components

A few years ago, I hosted my blog on Dreamhost. They’ve customized something inside the blog which means it doesn’t automatically update itself. I’ve long since moved this blog off to my own hosting, but I can’t figure out which thing it was they changed, and I’ve got so much content and stuff in here, I don’t really want to mess with it.

Anyway, I like keeping my systems up to date, and I hate logging into a blog and finding updates are pending, so I wrote this script. It uses wp-cli which I have installed to /usr/local/bin/wp as per the install guide. This is also useful if you’re hosting your site in such a way that you can’t make changes to core or plugins from the web interface.

This script updates:

  1. All core files (lines core update-db, core update and language core update)
  2. All plugins (lines plugin update --all and language plugin update --all)
  3. All themes (lines theme update --all and language theme update --all)

To remove any part of this script, just delete those lines, including the /usr/local/bin/wp and --quiet && \ fragments!

I then run sudo -u www-data crontab -e (replacing www-data with the real account name of the user who controls the blog, which can be found by doing an ls -l /var/www/html/ replacing the path to where your blog is located) and I add the bottom line to that crontab file (the rest is just comments to remind you what the fields are!)

#                                         day of month [1-31]
#                                             month [1-12]
#                                                 day of week [1-6 Mon-Sat, 0/7 Sun]
# minute   hour                                         command
1          1,3,5,7,9,11,13,15,17,19,21,23 *   *   *     /usr/local/bin/wp-upgrade.sh /var/www/jon.sprig.gs/blog

This means that every other hour, at 1 minute past the hour, every day, every month, I run the update :)

If you’ve got email setup for this host and user, you’ll get an email whenever it upgrades a component too.

"Root" by "llee_wu" on Flickr

A quick note on using Firefox in Windows in a Corporate or Enterprise environment

JonTheNiceGuy Leave a comment

I’ve been using Firefox as my “browser of choice” for around 15 years. I tend to prefer to use it for all sorts of reasons, but the main thing I expect is support for extensions. Not many of them, but … well, there’s a few!

There are two stumbling blocks for using Firefox in a corporate or enterprise setting. These are:

  1. NTLM or Kerberos Authentication for resources like Sharepoint and ADFS.
  2. Enterprise TLS certificates (usually deployed via GPO as part of the domain)

These are both trivially fixed in the about:config screen, but first you need to get past a scary looking warning page!

In the address bar, where it probably currently says jon.sprig.gs, click in there and type about:config.

Getting to about:config

This brings you to a scary page!

Proceed with caution! (of course!!)

Click the “Accept the Risk and Continue” (note, this is with Firefox 76. Wording with later or earlier versions may differ).

As if it wasn’t obvious enough from the previous screen, this “may impact performance and security”…

And then you get a search box.

In the “Search preference name” type in ntlm and find the line that says network.automatic-ntlm-auth.trusted-uris.

The “NTLM Options page”

Type in there the suffixes of any TRUSTED domains. For example, if your company uses the domain names of bigcompany.com, bigco.local and big.company then you’d type in:

bigcompany.com,bigco.local,big.company

Any pages that you browse to, where they request NTLM authentication, will receive an NTLM set of credentials if prompted (same as IE, Edge, and Chrome already do!) NTLM is effectively a way to pass a trusted Kerberos ticket (a bit like your domain credentials) into a web page.

Next up, let’s get those pesky certificate errors removed!

This assumes that you have a centrally managed TLS Root Certificate, and the admins in your network haven’t just been dumping self signed certificates everywhere (nothing gets around that… just sayin’).

Still in about:config, clear the search box and type enterprise, like this!

Enterprise Roots are here!

Find the line security.enterprise_roots.enabled and make sure it says true. If it doesn’t double click it, so it does.

Now you can close your preferences page, and you should be fine to visit your internal source code repository, time sheeting system or sharepoint site, with almost no interruptions!

If you’ve been tasked for turning this stuff on in your estate of managed desktop environment machines, then you might find this article (on Autoconfiguration of Firefox) of use (but I’ve not tried it!)

Featured image is “Root” by “llee_wu” on Flickr and is released under a CC-BY-ND license.

Screencast 005: SSH Keys and Client Configuration (a Mentoring style video)

JonTheNiceGuy 2 Comments

I’m back again with another Mentoring Style video, in which I talk about how to create and use SSH keys (although, in hindsight, not using PuTTY which I probably should have covered!) and how to use SSH Config Files to make your life easier.

Screencast 005: SSH Keys and Client Configuration

Also available on Archive.org and LBRY.

Much of the SSH config I created here was based on files I’ve uploaded to Github already.

Publishing a “Bio” in Secure Scuttlebutt, using ssb-server

JonTheNiceGuy Leave a comment

This is one of those “oh, there it is” posts, more for myself than anyone else. Anyway, if you use SSB from a shell (perhaps you run your own SSB Pub, for example), you might want to run this style of command:

ssb-server publish --type about --about "$(ssb-server whoami | jq .id -r)" --name "Some Server" --description "I'm just some server, you know"

As long as you have --name or --description in there, you should be good to go!

"vieux port Marseille" by "Jeanne Menjoulet" on Flickr

Networking tricks with Multipass in Virtualbox on Windows (Bridged interfaces and Port Forwards)

JonTheNiceGuy 15 Comments

TL;DR? Want to “just” bridge one or more interfaces to a Multipass instance when you’re using Virtualbox? See the Bridging Summary below. Want to do a port forward? See the Port Forward section below. You will need the psexec command and to execute this as an administrator. The use of these two may be considered a security incident on your computing environment, depending on how your security processes and infrastructure are defined and configured.

Ah Multipass. This is a tool created by Canonical to create a “A mini-cloud on your Mac or Windows workstation.” (from their website)…

I’ve often seen this endorsed as the tool of choice from Canonical employees to do “stuff” like run Kubernetes, develop tools for UBPorts (previously Ubuntu Touch) devices, and so on.

So far, it seems interesting. It’s a little bit like Vagrant with an in-built cloud-init Provisioner, and as I want to test out the cloud-init files I’m creating for AWS and Azure, that’d be so much easier than actually building the AWS or Azure machines, or finding a viable cloud-init plugin for Vagrant to test it out.

BUT… Multipass is really designed for Linux systems (running LibVirt), OS X (running HyperKit) and Windows (running Hyper-V). Even if I were using Windows 10 Pro on this machine, I use Virtualbox for “things” on my Windows Machine, and Hyper-V steals the VT-X bit, which means that VirtualBox can’t run x64 code…. Soooo I can’t use the Hyper-V mode.

Now, there is a “fix” for this. You can put Multipass into Virtualbox mode, which lets you run Multipass on Windows or OS X without using their designed-for hypervisor, but this has a downside, you see, VirtualBox doesn’t give MultiPass the same interface to route networking connections to the VM, and there’s currently no CLI or GUI options to say “bridge my network” or “forward a port” (in part because it needs to be portable to the native hypervisor options, apparently). So, I needed to fudge some things so I can get my beloved bridged connections.

I got to the point where I could do this, thanks to the responses to a few issues I raised on the Multipass Github issues, mostly #1333.

The first thing you need to install in Windows is PsExec, because Multipass runs it’s Virtual Machines as the SYSTEM account, and talking to SYSTEM account processes is nominally hard. Get PsExec from the SysInternals website. Some IT Security professionals will note the addition of PsExec as a potential security incident, but then again, they might also see the running of a virtual machine as a security incident too, as these aren’t controlled with a central image. Anyway… Just bear it in mind, and don’t shout at me if you get frogmarched in front of your CISO.

I’m guessing if you’re here, you’ve already installed Multipass, (but if not, and it seems interesting – it’s over at https://multipass.run. Get it and install it, then carry on…) and you’ve probably enabled the VirtualBox mode (if not – open a command prompt as administrator, and run “multipass set local.driver=virtualbox“). Now, you can start sorting out your bridges.

Sorting out bridges

First things first, you need to launch a virtual machine. I did, and it generated a name for my image.

C:\Users\JON>multipass launch
Launched: witty-kelpie

Fab! We have a running virtual machine, and you should be able to get a shell in there by running multipass shell "witty-kelpie" (the name of the machine it launched before). But, uh-oh. We have the “default” NAT interface of this device mapped, not a bridged interface.

C:\Users\JON>multipass shell "witty-kelpie"
Welcome to Ubuntu 18.04.3 LTS (GNU/Linux 4.15.0-76-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Feb  6 10:56:38 GMT 2020

  System load:  0.3               Processes:             82
  Usage of /:   20.9% of 4.67GB   Users logged in:       0
  Memory usage: 11%               IP address for enp0s3: 10.0.2.15
  Swap usage:   0%


0 packages can be updated.
0 updates are security updates.


To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@witty-kelpie:~$

So, exit the machine, and issue a multipass stop "witty-kelpie" command to ask Virtualbox to shut it down.

So, this is where the fun[1] part begins.
[1] The “Fun” part here depends on how you view this specific set of circumstances 😉

We need to get the descriptions of all the interfaces we might want to bridge to this device. I have three interfaces on my machine – a WiFi interface, a Ethernet interface on my laptop, and an Ethernet interface on my USB3 dock. At some point in the past, I renamed these interfaces, so I’d recognise them in the list of interfaces, so they’re not just called “Connection #1”, “Connection #2” and so on… but you should recognise your interfaces.

To get this list of interfaces, open PowerShell (as a “user”), and run this command:

PS C:\Users\JON> Get-NetAdapter -Physical | format-list -property "Name","DriverDescription"

Name              : On-Board Network Connection
DriverDescription : Intel(R) Ethernet Connection I219-LM

Name              : Wi-Fi
DriverDescription : Intel(R) Dual Band Wireless-AC 8260

Name              : Dock Network Connection
DriverDescription : DisplayLink Network Adapter NCM

For reasons best known to the Oracle team, they use the “Driver Description” to identify the interfaces, not the name assigned to the device by the user, so, before we get started, find your interface, and note down the description for later. If you want to bridge “all” of them, make a note of all the interfaces in question, and in the order you want to attach them. Note that Virtualbox doesn’t really like exposing more than 8 NICs without changing the Chipset to ICH9 (but really… 9+ NICs? really??) and the first one is already consumed with the NAT interface you’re using to connect to it… so that gives you 7 bridgeable interfaces. Whee!

So, now you know what interfaces you want to bridge, let’s configure the Virtualbox side. Like I said before you need psexec. I’ve got psexec stored in my Downloads folder. You can only run psexec as administrator, so open up an Administrator command prompt or powershell session, and run your command.

Just for clarity, your commands are likely to have some different paths, so remember that wherever “your” PsExec64.exe command is located, mine is in C:\Users\JON\Downloads\sysinternals\PsExec64.exe, and wherever your vboxmanage.exe is located, mine is in C:\Program Files\Oracle\VirtualBox\vboxmanage.exe.

Here, I’m going to attach my dock port (“DisplayLink Network Adapter NCM”) to the second VirtualBox interface, the Wifi adaptor to the third interface and my locally connected interface to the fourth interface. Your interfaces WILL have different descriptions, and you’re likely not to need quite so many of them!

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" modifyvm "witty-kelpie" --nic2 bridged --bridgeadapter2 "DisplayLink Network Adapter NCM" --nic3 bridged --bridgeadapter3 "Intel(R) Dual Band Wireless-AC 8260" --nic4 bridged --bridgeadapter4 "Intel(R) Ethernet Connection I219-LM"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

An error code of 0 means that it completed successfuly and with no issues.

If you wanted to use a “Host Only” network (if you’re used to using Vagrant, you might know it as “Private” Networking), then change the NIC you’re interested in from --nicX bridged --bridgeadapterX "Some Description" to --nicX hostonly --hostonlyadapterX "VirtualBox Host-Only Ethernet Adapter" (where X is replaced with the NIC number you want to swap, ranged between 2 and 8, as 1 is the NAT interface you use to SSH into the virtual machine.)

Now we need to check to make sure the machine has it’s requisite number of interfaces. We use the showvminfo flag to the vboxmanage command. It produces a LOT of content, so I’ve manually filtered the lines I want, but you should spot it reasonably quickly.

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" showvminfo "witty-kelpie"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com


Name:                        witty-kelpie
Groups:                      /Multipass
Guest OS:                    Ubuntu (64-bit)
<SNIP SOME CONTENT>
NIC 1:                       MAC: 0800273CCED0, Attachment: NAT, Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 1 Settings:  MTU: 0, Socket (send: 64, receive: 64), TCP Window (send:64, receive: 64)
NIC 1 Rule(0):   name = ssh, protocol = tcp, host ip = , host port = 53507, guest ip = , guest port = 22
NIC 2:                       MAC: 080027303758, Attachment: Bridged Interface 'DisplayLink Network Adapter NCM', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 3:                       MAC: 0800276EA174, Attachment: Bridged Interface 'Intel(R) Dual Band Wireless-AC 8260', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 4:                       MAC: 080027042135, Attachment: Bridged Interface 'Intel(R) Ethernet Connection I219-LM', Cable connected: on, Trace: off (file: none), Type: 82540EM, Reported speed: 0 Mbps, Boot priority: 0, Promisc Policy: deny, Bandwidth group: none
NIC 5:                       disabled
NIC 6:                       disabled
NIC 7:                       disabled
NIC 8:                       disabled
<SNIP SOME CONTENT>

Configured memory balloon size: 0MB

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

Fab! We now have working interfaces… But wait, let’s start that VM back up and see what happens.

C:\Users\JON>multipass shell "witty-kelpie"
Welcome to Ubuntu 18.04.3 LTS (GNU/Linux 4.15.0-76-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Thu Feb  6 11:31:08 GMT 2020

  System load:  0.1               Processes:             84
  Usage of /:   21.1% of 4.67GB   Users logged in:       0
  Memory usage: 11%               IP address for enp0s3: 10.0.2.15
  Swap usage:   0%


0 packages can be updated.
0 updates are security updates.


Last login: Thu Feb  6 10:56:45 2020 from 10.0.2.2
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@witty-kelpie:~$

Wait, what….. We’ve still only got the one interface up with an IP address… OK, let’s fix this!

As of Ubuntu 18.04, interfaces are managed using Netplan, and, well, when the VM was built, it didn’t know about any interface past the first one, so we need to get Netplan to get them enabled. Let’s check they’re detected by the VM, and see what they’re all called:

ubuntu@witty-kelpie:~$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:3c:ce:d0 brd ff:ff:ff:ff:ff:ff
3: enp0s8: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:30:37:58 brd ff:ff:ff:ff:ff:ff
4: enp0s9: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:6e:a1:74 brd ff:ff:ff:ff:ff:ff
5: enp0s10: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 08:00:27:04:21:35 brd ff:ff:ff:ff:ff:ff
ubuntu@witty-kelpie:~$

If you compare the link/ether lines to the output from showvminfo we executed before, you’ll see that the MAC address against enp0s3 matches the NAT interface, while enp0s8 matches the DisplayLink adapter, and so on… So we basically want to ask NetPlan to do a DHCP lookup for all the new interfaces we’ve added to it. If you’ve got 1 NAT and 7 physical interfaces (why oh why…) then you’d have enp0s8, 9, 10, 16, 17, 18 and 19 (I’ll come back to the random numbering in a tic)… so we now need to ask Netplan to do DHCP on all of those interfaces (assuming we’ll be asking for them all to come up!)

If we want to push that in, then we need to add a new file in /etc/netplan called something like 60-extra-interfaces.yaml, that should contain:

network:
  ethernets:
    enp0s8:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 10
    enp0s9:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 11
    enp0s10:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 12
    enp0s16:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 13
    enp0s17:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 14
    enp0s18:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 15
    enp0s19:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 16

Going through this, we basically ask netplan not to assume the interfaces are attached. This stops the boot process for waiting for a timeout to configure each of the interfaces before proceeding, so it means your boot should be reasonably fast, particularly if you don’t always attach a network cable or join a Wifi network on all your interfaces!

We also say to assume we want IPv4 DHCP on each of those interfaces. I’ve done IPv4 only, as most people don’t use IPv6 at home, but if you are doing IPv6 as well, then you’d also need the same lines that start dhcp4 copied to show dhcp6 (like dhcp6: yes and dhcp6-overrides: route-metric: 10)

The eagle eyed of you might notice that the route metric increases for each extra interface. This is because realistically, if you have two interfaces connected (perhaps if you’ve got wifi enabled, and plug a network cable in), then you’re more likely to want to prioritize traffic going over the lower numbered interfaces than the higher number interfaces.

Once you’ve created this file, you need to run netplan apply or reboot your machine.

So, yehr, that gets you sorted on the interface front.

Bridging Summary

To review, you launch your machine with multipass launch, and immediately stop it with multipass stop "vm-name", then, as an admin, run psexec vboxmanage modifyvm "vm-name" --nic2 bridged --bridgedadapter2 "NIC description", and then start the machine with multipass start "vm-name". Lastly, ask the interface to do DHCP by manipulating your Netplan configuration.

Interface Names in VirtualBox

Just a quick note on the fact that the interface names aren’t called things like eth0 any more. A few years back, Ubuntu (amongst pretty much all of the Linux distribution vendors) changed from using eth0 style naming to what they call “Predictable Network Interface Names”. This derives the names from things like, what the BIOS provides for on-board interfaces, slot index numbers for PCI Express ports, and for this case, the “geographic location of the connector”. In Virtualbox, these interfaces are provided as the “Geographically” attached to “port 0” (so enp0 are all on port 0), but for some reason, they broadcast themselves as being attached to the port 0 at “slots” 3, 8, 9, 10, 16, 17, 18 and 19… hence enp0s3 and so on. shrug It just means that if you don’t have the interfaces coming up on the interfaces you’re expecting, you need to run ip link to confirm the MAC addresses match.

Port Forwarding

Unlike with the Bridging, we don’t need to power down the VM to add the extra interfaces, we just need to use psexec (as an admin again) to execute a vboxmanage command – in this case, it’s:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" controlvm "witty-kelpie" --natpf1 "myport,tcp,,1234,,2345"

OK, that’s a bit more obscure. Basically it says “Create a NAT rule on NIC 1 called ‘myport’ to forward TCP connections from port 1234 attached to any IP associated to the host OS to port 2345 attached to the DHCP supplied IP on the guest OS”.

If we wanted to run a DNS server in our VM, we could run multiple NAT rules in the same command, like this:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" controlvm "witty-kelpie" --natpf1 "TCP DNS,tcp,127.0.0.1,53,,53" --natpf1 "UDP DNS,udp,127.0.0.1,53,,53"

If we then decide we don’t need those NAT rules any more, we just (with psexec and appropriate paths) issue: vboxmanage controlvm "vm-name" --natpf1 delete "TCP DNS"

Using ifupdown instead of netplan

Late Edit 2020-04-01: On Github, someone asked me how they could use the same type of config with netplan, but instead on a 16.04 system. Ubuntu 16.04 doesn’t use netplan, but instead uses ifupdown instead. Here’s how to configure the file for ifupdown:

You can either add the following stanzas to /etc/network/interfaces, or create a separate file for each interface in /etc/network/interfaces.d/<number>-<interface>.cfg (e.g. /etc/network/interfaces.d/10-enp0s8.cfg)

allow-hotplug enp0s8
iface enp0s8 inet dhcp
  metric 10

To re-iterate, in the above netplan file, the interfaces we identified were: enp0s8, enp0s9, enp0s10, enp0s16, enp0s17, enp0s18 and enp0s19. Each interface was incrementally assigned a route metric, starting at 10 and ending at 16, so enp0s8 has a metric of 10, while enp0s16 has a metric of 13, and so on. To build these files, I’ve created this brief shell script you could use:

export metric=10
for int in 8 9 10 16 17 18 19
do
  echo -e "allow-hotplug enp0s${int}\niface enp0s${int} inet dhcp\n  metric $metric" > /etc/network/interfaces.d/enp0s${int}.cfg
  ((metric++))
done

As before, you could reboot to make the changes to the interfaces. Bear in mind, however, that unlike Netplan, these interfaces will try and DHCP on boot with this configuration, so boot time will take longer if every interface attached isn’t connected to a network.

Using NAT Network instead of NAT Interface

Late update 2020-05-26: Ruzsinsky contacted me by email to ask how I’d use a “NAT Network” instead of a “NAT interface”. Essentially, it’s the same as the Bridged interface above, with one other tweak first, we need to create the Net Network, with this command (as an Admin)

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" natnetwork add --netname MyNet --network 192.0.2.0/24

Next, stop your multipass virtual machine with multipass stop "witty-kelpie", and configure your second interface, like this:

C:\WINDOWS\system32>C:\Users\JON\Downloads\sysinternals\PsExec64.exe -s "c:\program files\oracle\virtualbox\vboxmanage" modifyvm "witty-kelpie" --nic2 natnetwork --nat-network2 "MyNet"

PsExec v2.2 - Execute processes remotely
Copyright (C) 2001-2016 Mark Russinovich
Sysinternals - www.sysinternals.com

c:\program files\oracle\virtualbox\vboxmanage exited on MINILITH with error code 0.

Start the vm with multipass start "witty-kelpie", open a shell with it multipass shell "witty-kelpie", become root sudo -i and then configure the interface in /etc/netplan/60-extra-interfaces.yaml like we did before:

network:
  ethernets:
    enp0s8:
      optional: yes
      dhcp4: yes
      dhcp4-overrides:
        route-metric: 10

And then run netplan apply or reboot.

What I would say, however, is that the first interface seems to be expected to be a NAT interface, at which point, having a NAT network as well seems a bit pointless. You might be better off using a “Host Only” (or “Private”) network for any inter-host communications between nodes at a network level… But you know your environments and requirements better than I do :)

Featured image is “vieux port Marseille” by “Jeanne Menjoulet” on Flickr and is released under a CC-BY-ND license.

"Unnatural Love" by "Keith Garner" on Flickr

Configuring a Remote Desktop (Gnome Shell) for Ubuntu

JonTheNiceGuy Leave a comment

I started thinking a couple of weeks ago, when my coding laptop broke, that it would be really useful to have a development machine somewhere else that I could use.

It wouldn’t need a lot of power (after all, I’m mostly developing web apps and not compiling stuff), but it does need to be a desktop OS, as I rather like being able to open code editors and suchlike, while I’ve got a web browser open.

I have an Android tablet, which while it’s great for being a tablet, it’s not much use as a desktop, and … yes, I’ve got a work laptop, but I don’t really want to install software on that (and I don’t think my admin team would be happy if I did).

Also, I quite like Linux.

Some time ago, I spotted that AWS has a “Virtual Desktop” environment, and I think that’s kinda what I’m after. Something I can spin up, run for a bit and then shut it down, so I thought I’d build something like that… but not pesky Windows, after all… who likes Windows, eh? ;)

So, I built a Virtual Desktop Environment (VDE) in AWS, using Terraform and a bit of shell script!

I start from an Ubuntu 18.04 server image, and, after the install is complete, I run this user-data script inside it. Yes, I know I could be doing this with Ansible, but… eh, I wanted it to be a quick deployment ;)

Oh, and there’s a couple of Terraform managed variables in here – ${aws_eip.vde.public_ip} is the AWS public IP address assigned to this host., ${var.firstuser} is the username we want to rename “ubuntu” (the stock server username) to. ${var.firstgecos} is the user’s “real name” which the machine identifies the user as (like “Log out Jon Spriggs” and so on). ${var.userpw} is either the password you want it to use, OR (by default) pwgen 12 which generates a 12 character long password. ${var.desktopenv} is the name of the desktop environment I want to install (Ubuntu by default) and … well, ${var.var_start} is a bit of a fudge, because I couldn’t, in a hurry, work out how to tell Terraform not to mangle the bash variable allocation of ${somevar} which is the format that Terraform also uses. D’oh.

#! /bin/bash
#################
# Set Hostname
#################
hostnamectl set-hostname vde.${aws_eip.vde.public_ip}.nip.io
#################
# Change User
#################
user=${var.firstuser}
if [ ! "$user" == 'ubuntu' ]
then
  until usermod -c "${var.firstgecos}" -l $user ubuntu ; do sleep 5 ; done
  until groupmod -n $user ubuntu ; do sleep 5 ; done
  until usermod  -d /home/$user -m $user ; do sleep 5 ; done
  if [ -f /etc/sudoers.d/90-cloudimg-ubuntu ]; then
    mv /etc/sudoers.d/90-cloudimg-ubuntu /etc/sudoers.d/90-cloud-init-users
  fi
  perl -pi -e "s/ubuntu/$user/g;" /etc/sudoers.d/90-cloud-init-users
fi
if [ '${var.userpw}' == '$(pwgen 12)' ]
then 
  apt update && apt install pwgen
fi
newpw="${var.userpw}"
echo "$newpw" > /var/log/userpw
fullpw="$newpw"
fullpw+="\n"
fullpw+="$newpw"
echo -e "$fullpw" | passwd $user
##########################
# Install Desktop and RDP
##########################
apt-get update
export DEBIAN_FRONTEND=noninteractive
apt-get full-upgrade -yq
apt-get autoremove -y
apt-get autoclean -y
apt-get install -y ${var.desktopenv}-desktop xrdp certbot
##########################
# Configure Certbot
##########################
echo "#!/bin/sh" > /etc/letsencrypt/merge_cert.sh
echo 'cat ${var.var_start}{RENEWED_LINEAGE}/privkey.pem ${var.var_start}{RENEWED_LINEAGE}/fullchain.pem > ${var.var_start}{RENEWED_LINEAGE}/merged.pem' >> /etc/letsencrypt/merge_cert.sh
echo 'chmod 640 ${var.var_start}{RENEWED_LINEAGE}/merged.pem' >> /etc/letsencrypt/merge_cert.sh
chmod 750 /etc/letsencrypt/merge_cert.sh
certbot certonly --standalone --deploy-hook /etc/letsencrypt/merge_cert.sh -n -d vde.${aws_eip.vde.public_ip}.nip.io -d ${aws_eip.vde.public_ip}.nip.io --register-unsafely-without-email --agree-tos
# Based on https://www.snel.com/support/xrdp-with-lets-encrypt-on-ubuntu-18-04/
sed -i 's~^certificate=$~certificate=/etc/letsencrypt/live/vde.${aws_eip.vde.public_ip}.nip.io/fullchain.pem~; s~^key_file=$~key_file=/etc/letsencrypt/live/vde.${aws_eip.vde.public_ip}.nip.io/privkey.pem' /etc/xrdp/xrdp.ini
##############################
# Fix colord remote user issue
##############################
# Derived from http://c-nergy.be/blog/?p=12043
echo "[Allow Colord all Users]
Identity=unix-user:*
Action=org.freedesktop.color-manager.create-device;org.freedesktop.color-manager.create-profile;org.freedesktop.color-manager.delete-device;org.freedesktop.color-manager.delete-profile;org.freedesktop.color-manager.modify-device;org.freedesktop.color-manager.modify-profile
ResultAny=no
ResultInactive=no
ResultActive=yes" > /etc/polkit-1/localauthority/50-local.d/45-allow.colord.pkla
##############################
# Configure Desktop
##############################
if [ '${var.desktopenv}' == 'ubuntu' ]
then 
  echo "#!/bin/bash" > /tmp/desktop_settings
  echo "gsettings set org.gnome.desktop.input-sources sources \"[('xkb', 'gb')]\"" >> /tmp/desktop_settings
  echo "gsettings set org.gnome.desktop.app-folders folder-children \"['Utilities', 'Sundry', 'YaST']\"" >> /tmp/desktop_settings
  echo "gsettings set org.gnome.desktop.privacy report-technical-problems false" >> /tmp/desktop_settings
  echo "gsettings set org.gnome.desktop.screensaver lock-enabled false" >> /tmp/desktop_settings
  echo "gsettings set org.gnome.desktop.session idle-delay 0" >> /tmp/desktop_settings
  echo "echo yes > /home/${var.firstuser}/.config/gnome-initial-setup-done" >> /tmp/desktop_settings
  sudo -H -u ${var.firstuser} dbus-launch --exit-with-session bash /tmp/desktop_settings
  rm -f /tmp/desktop_settings
fi
##########################
# Install VSCode
##########################
wget https://vscode-update.azurewebsites.net/latest/linux-deb-x64/stable -O /tmp/vscode.deb
apt install -y /tmp/vscode.deb
rm /var/crash/*
shutdown -r now

Ubuntu 18.04 has a “first login” wizard, that lets you pre-set up things like, what language will you be using. I bypassed this with the gsettings commands towards the end of the script, and writing the string “yes” to ~/.config/gnome-initial-setup-done.

Also, I wanted to be able to RDP to it. I’m a bit concerned by the use of VNC, especially where RDP is more than capable. It’s just an apt-install away, so… that’s what I do. But, because I’m RDP’ing into this box, I wanted to prevent the RDP session from locking, so I provide two commands to the session: gsettings set org.gnome.desktop.screensaver lock-enabled false which removes the screensaver’s ability to lock the screen, and gsettings set org.gnome.desktop.session idle-delay 0 which stops the screensaver from even starting in the first place.

Now all I need to do is to figure out where I’m going to store my code between boots ;)

So, in summary, I now have a Virtual Machine, which runs Ubuntu 18.04 Desktop, in AWS, with an RDP connection (powered by xRDP), and a disabled screensaver. Job done, I think!

Oh, and if I’m doing it “wrong”, let me know in the comments? :)

Featured image is “Unnatural Love” by “Keith Garner” on Flickr and is released under a CC-BY-SA license.

"Mesh Facade" by "Pedro Ângelo" on Flickr

Looking at the Nebula Overlay Meshed VPN Network from Slack

JonTheNiceGuy Leave a comment

Around 2-3 years ago, Slack– the company who produces Slack the IM client, started working on a meshed overlay network product, called Nebula, to manage their environment. After two years of running their production network on the back of it, they decided to open source it. I found out about Nebula via a Medium Post that was mentioned in the HangOps Slack Group. I got interested in it, asked a few questions about Nebula in the Slack, and then in the Github Issues for it, and then recently raised a Pull Request to add more complete documentation than their single (heavily) commented config file.

So, let’s go into some details on why this is interesting to me.

1. Nebula uses a flat IPv4 network to identify all hosts in the network, no matter where in the network those hosts reside.

This means that I can address any host in my (self allocated) 198.18.0.0/16 network, and I don’t need to worry about routing tables, production/DR sites, network tromboneing and so on… it’s just… Flat.

[Note: Yes, that IP address “looks” like a public subnet – but it’s actually a testing network, allocated by IANA for network testing!]

2. Nebula has host-based firewalling built into the configuration file.

This means that once I know how my network should operate (yes, I know that’s a big ask), I can restrict my servers from being able to reach my laptops, or I can stop my web server from being able to talk to my database server, except for on the database ports. Lateral movement becomes a LOT harder.

This firewalling also looks a lot like (Network) Security Groups (for the AWS and Azure familiar), so you have a default “Deny” rule, and then layer “Allow” rules on top. You also have Inbound and Outbound rules, so if you want to stop your laptops from talking anything but DNS, SSH, HTTPS and ICMP over Nebula…. well, yep, you can do that :)

3. Nebula uses a PKI environment. Where you can have multiple Certificate Authorities.

This means that I have a central server running my certificate authority (CA), with a “backup” CA, stored offline – in case of dire disaster with my primary CA, and push both CA’s to all my nodes. If I suddenly need to replace all the certificates that my current CA signed, I can do that with minimal interruption to my nodes. Good stuff.

Nebula also created their own PKI attributes to identify the roles of each device in the Nebula environment. By signing that as part of the certificate on each node too, means your CA asserts that the role that certificate holds is valid for that node in the network.

Creating a node’s certificate is a simple command:

nebula-cert sign -name jon-laptop -ip 198.18.0.1/16 -groups admin,laptop,support

This certificate has the IP address of the node baked in (it’s 198.18.0.1) and the groups it’s part of (admin, laptop and support), as well as the host name (jon-laptop). I can use any of these three items in my firewall rules I mentioned above.

4. It creates a peer-to-peer, meshed VPN.

While it’s possible to create a peer-to-peer meshed VPN with commercial products, I’ve not seen any which are as light-weight to deploy as this. Each node finds all the other nodes in the network by using a collection of “Lighthouses” (similar to Torrent Seeds or Skype Super Nodes) which tells all the connecting nodes where all the other machines in the network are located. These then initiate UDP connections to the other nodes they want to talk to. If they are struggling (because of NAT or Double NAT), then there’s a NAT Punching process (called, humourously, “punchy”) which lets you signal via the Lighthouse that you’re trying to reach another node that can’t see your connection, and asks it to also connect out to you over UDP… thereby fixing the connection issue. All good.

5. Nebula has clients for Windows, Mac and Linux. Apparently there are clients for iOS in the works (meh, I’m not on Apple… but I know some are) and I’ve heard nothing about Android as yet, but as it’s on Linux, I’m sure some enterprising soul can take a look at it (the client is written in Go).

If you want to have a look at Nebula for your own testing, I’ve created a Terraform based environment on AWS and Azure to show how you’d manage it all using Ansible Tower, which builds:

2 VPCs (AWS) and 1 VNet (Azure)
6 subnets (3 public, 3 private)
1 public AWX (the upstream project from Ansible Tower) Server
1 private Nebula Certificate Authority
2 public Web Servers (one in AWS, one in Azure)
2 private Database Servers (one in AWS, one in Azure)
2 public Bastion Servers (one in AWS, one in Azure) – that lets AWX reach into the Private sections of the network, without exposing SSH from all the hosts.

If you don’t want to provision the Azure side, just remove load_web2_module.tf from the Terraform directory in that repo… Job’s a good’n!

I have plans to look at a couple of variables, like Nebula’s closest rival, ZeroTier, and to look at using SaltStack instead of Ansible, to reduce the need for the extra Bastion servers.

Featured image is “Mesh Facade” by “Pedro Ângelo” on Flickr and is released under a CC-BY-SA license.

"Key mess" by "Alper Çuğun" on Flickr

Making Ansible Keys more useful in complex and nested data structures

JonTheNiceGuy Leave a comment

One of the things I miss about Jekyll when I’m working with Ansible is the ability to fragment my data across multiple files, but still have it as a structured *whole* at the end.

For example, given the following directory structure in Jekyll:

+ _data
|
+---+ members
|   +--- member1.yml
|   +--- member2.yml
|
+---+ groups
    +--- group1.yml
    +--- group2.yml

The content of member1.yml and member2.yml will be rendered into site.data.members.member1 and site.data.members.member2 and likewise, group1 and group2 are loaded into their respective variables.

This kind of structure isn’t possible in Ansible, because all the data files are compressed into one vars value that we can read. To work around this on a few different projects I’ve worked on, I’ve ended up doing the following:

- set_fact:
    my_members: |-
      [
        {%- for var in vars | dict2items -%}
          {%- if var.key | regex_search(my_regex) is not none -%}
            "{{ var.key | regex_replace(my_regex, '') }}": 
              {%- if var.value | string %}"{% endif -%}
              {{ var.value }}
              {%- if var.value | string %}"{% endif %},
          {%- endif -%}
        {%- endfor -%}
      ]
  vars:
    my_regex: '^member_'

So, what this does is to step over all the variables defined (for example, in host_vars\*, group_vars\*, from the gathered facts and from the role you’re in – following Ansible’s loading precedence), and then checks to see whether the key of that variable name (e.g. “member_i_am_a_member” or “member_1”) matches the regular expression (click here for more examples). If it does, the key (minus the regular expression matching piece [using regex_replace]) is added to a dictionary, and the value attached. If the value is actually a string, then it wraps it in quotes.

So, while this doesn’t give me my expressive data structure that Jekyll does (no site.data.members.member1.somevalue for me), I do at least get to have my_members.member1.somevalue if I put the right headers in! :)

I’ll leave extending this model for doing other sorts of building variables out (for example, something like if var.value['variable_place'] | default('') == 'my_members.member' + current_position) to the reader to work out how they could use something like this in their workflows!

Featured image is “Key mess” by “Alper Çuğun” on Flickr and is released under a CC-BY license.