"Money" by "Images Money" on Flickr

One to listen to: “Salary Negotiation for DevOps with Josh Doody”

A few weeks ago, during a podcast binge, I came across this podcast (Salary Negotiations for DevOps with Josh Doody on the Real World DevOps Podcast). I noted at the time that it was really good content with great advice… and then forgot about it. (Oh, and it’s not just for DevOps people!)

Fast forward to today, when one of the Admin Admin Podcast Listeners (in our Telegram Channel) announces that he’s just gone for a new job, had been offered it, and was thinking of taking the job… but that they’d offered him a package lower than he was hoping to receive. My response “Say you wanted more, see if they can meet you halfway!” The main thing I took away from this podcast was that by the time you’re in the interview stage, the company you’re being interviewed by is *likely* to have already paid several thousand pounds/dollars/euros to have you sat in front of them, so if they want you, they’ll probably pay that bit more to not have to go through that process again!

Anyway, this is a great podcast for anyone who works for an employer, is thinking of asking for a pay rise‌ or is looking for a new job, and it’s well worth a listen!

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

"Wifi Here on a Blackboard" by "Jem Stone" on Flickr

Free Wi-Fi does not need to be password-less!

Recently a friend of mine forwarded an email to me about a Wi-fi service he wanted to use from a firm, but he raised some technical questions with them which they seemed to completely misunderstand!

So, let’s talk about the misconceptions of Wi-fi passwords.

Many people assume that when you log into a system, it means that system is secure. For example, logging into a website makes sure that your data is secure and protected, right? Not necessarily – the password you entered could be on a web page that is not secured by TLS, or perhaps the web server doesn’t properly transfer it’s contents to a database. Maybe the website was badly written, and means it’s vulnerable to one of a handful of common attacks (with fun names like “Cross Site Scripting” or “SQL Injection Attacks”)…

People also assume the same thing about Wi-fi. You reached a log in page, so it must be secure, right? It depends. If you didn’t put in a password to access the Wi-fi in the first place (like in the image of the Windows 10 screen, or on my KDE Desktop) then you’re probably using Unsecured Wi-fi.

An example of a secured Wi-fi sign-in box on Windows 10
The same Wi-fi sign in box on KDE Neon

People like to compare network traffic to “sending things through the post”, notablycomparing E-Mail to “sending a postcard”, versus PGP encrypted E-Mail being compared to “sending a sealed letter”. Unencrypted Wi-fi is like using CB. Anyone who can hear your signal can understand what you are saying… but if you visit a website which uses HTTPS, then it’s like listening to someone saying random numbers over the radio.

And, if you’re using Unencrypted Wi-fi, it’s also possible for an attacker to see what website you visited, because the request for the address to reach on the Internet (e.g. “Google.com” = 172.217.23.14) is sent in the clear. Also because of the way that DNS works (that name to address matching thing) means that if someone knows you’re visiting a “site of interest” (like, perhaps a bank website), they can reply *before* the real DNS server, and tell you that the server on their machine is actually your bank’s website.

So, many of these things can be protected against by using a simple method, that many people who provide Wi-fi don’t do.

Turn on WPA2 (the authentication bit). Even if *everyone* uses the same password (which they’d have to for WPA2), the fact you’re logging into the Access Point means it creates a unique shared secret for your session.

“But hang on”, I hear the guy at the back cry, “you used the same password – how does that work?”

OK, so this is where the fun stuff starts. The password is just part of how you negotiate to get on to the network. There’s a complex beast of a method that explains how get a shared unique secret when you’re passing stuff around “in the clear”, and so as a result, when you first connect to that Wi-fi access point, and you hand over your password, it “Authorises” you on to the network, but then hands you over to the encryption part, where you generate a key and then use that to talk to each other. The encryption is the bit like “HTTPS”, where you make it so that people can’t see what you’re looking at.

“I got told that if everyone used the same password” said a hipster in the front row, “I wouldn’t be able to tell them apart.” Aha, not true. You can have a separate passphrase to access the Wi-fi from the Login page, after all, you’ve got to make sure that people aren’t breaking the rules (which they *TOTALLY* read, before clicking “I agree, just get me on the damn Wi-fi already”) by using your network.

“OK”, says the lady over on the right, “but when I connected to the Wi-fi, they asked me to log in using Facebook – that’s secure, right?”

Um, no. Well, maybe. See, if they gave you a WPA2 password to log into the Wi-fi, and then the first thing you got to was that login screen, then yep, it’s all good! {*} You can browse with (relative) impunity. But if they didn’t… well, not only are they asking you to shout your secrets on the radio, but if you’re really unlucky, the page asking you to log into Facebook might *also* not actually be Facebook, but another website that just looks like Facebook… after all, I’m sure that page you went to complained that it wasn’t Google or Facebook when you tried to open it…

{*} Except for the fact they’re asking you to tell them not only who you are, but who you’re also friends with, where you went to school, what your hobbies are, what groups you’re in, your date of birth and so on.

But anyway. I understand why those login screens are there. They’re asserting that not only do you understand that you mustn’t use their network for bad things, but that if the police come and ask them who used their network to do something naughty, they can say “He said his name was ‘Bob Smith’ and his email address was ‘bob@example.com’, Officer”…

It also means that the “free” service they provide to you, usually at some great expense (*eye roll*) can get them some return on investment (like, they just got your totally-real-and-not-at-all-made-up-email-address… honest, and they also know what websites you visited while you were there, which they can sell on).

So… What to do the next time you “need” Wi-fi, and there’s a free service there? Always use a VPN when you’re not using a network you trust. If the Wi-fi isn’t using WPA2 encryption (even something as simple as “Buy a drink first” is a great passphrase to use!) point them to this page, and tell them it’s virtually pain free (as long as the passphrase is easy to remember, easy to type and doesn’t have too many weird symbols in) and makes their service more safe and secure for their customers…

Featured image is “Wifi Here on a Blackboard” by “Jem Stone” on Flickr and is released under a CC-BY license.

"Centralized, Decentralized, Distributed" by "Amber Case" on Flickr

A brief summary of Terminology about non-centralised applications

I hang out in the #redecentralize matrix group, and yesterday one of the group asked a question about getting clarification on the terminology. Here’s what I wrote:

Self Hosted: An application (usually running on a server) that you run in your own environment.

Examples include: Ethercalc, Sandstorm, WordPress.

[Note, Self Hosted services may still be classed as self-hosted, even if you don’t manage the environment yourself, for example, if you use a Virtual Machine, a Virtual Private Server, or pay someone like modular.im to build and run it for you – provided you can migrate your hosted application to your own environment if you want to]

P2P (Peer to Peer): A locally running application (or client) which predominantly talks to other clients (referred to as a peer), not to a server. There may be a central server which helps facilitate the initial connection between applications, but this is typically only used for that introduction. There may also be a semi-fixed list of “seed nodes” used to discover other nodes in the network.

Examples include: Bittorrent, Secure Scuttlebutt

[Many VoIP systems will have some sort of federated connection between “signalling” nodes, but have a P2P connection for the Audio/Visual streams.]

Federated: A server-based application that can talk to other server applications. (Federation can also refer to the method by which they find each other – either by responses to specific HTTP(s) requests or from particular DNS records).

Examples include: Matrix.org, Mastodon

Distributed: This is more how data is processed – if it’s centralised but distributed (e.g. Facebook, Netflix) then a central server instructs other servers how to act, and the nodes perform actions on behalf of the server. When talking about Decentralised, this means that you could have several nodes cooperating on an activity.

Examples include: BOINC, DNS

Blockchain: A distributed, secure, append-only database. May be P2P or Federated.

Examples include: Bitcoin

Decentralised: Any application which does not require a central service to function. Usually implies Self hosted.

Examples include: Collabora Online, “Internet Mail” (the original decentralised service!)

Enhanced from a message sent to the #redentralize:matrix.org chat, following advice from participants in the group

I hope you find this list of definitions useful!

(Edited 2019-02-21 to address comments from Ben in the Binary Times Telegram group, also others from mylo5ha5 in the Redecentralize group. Typo fixed, thanks to uhoreg)

Featured image is “Centralized, Decentralized, Distributed” by “Amber Case” on Flickr and is released under a CC-BY-NC license.

"Juniper NetScreen 25 Firewall front" by "jackthegag" on Flickr

Standard Firewall Rules

One of the things I like to do is to explain how I set things up, but a firewall is one of those things that’s a bit complicated, because it depends on your situation, and what you’re trying to do in your environment. That said, there’s a template that you can probably get away with deploying, and see if it works for your content, and then you’ll see where to add the extra stuff from there. Firewall policies typically work from the top down.

This document will assume you have a simple boundary firewall. This simple firewall has two interfaces, the first being an “Outside” interface, connected to your ISP, with an IPv4 address of 192.0.2.2/24 and a default gateway of 192.0.2.1, it also has a IPv6 address of 2001:db8:123c:abd::2/64 and a default gateway address of 2001:db8:123c:abd::1. The second “Inside” interface, where your protected network is attached, has an IPv4 address of 198.51.100.1/24 and an IPv6 address of 2001:db8:123d:abc::1/64. On this inside interface, the firewall is the default gateway for the inside network.

I’ll be using simple text rules to describe firewall policies, following this format:

Source Interface: <outside | inside>
Source IP Address: <x.x.x.x/x | "any">
NAT Source IP Address: <x.x.x.x/x | no>
Destination Interface: <outside | inside>
Destination IP Address: <x.x.x.x/x | "any">
NAT Destination IP Address: <x.x.x.x/x | no>
Destination Port: <tcp | udp | icmp | ip>/<x>
Action: <allow | deny | reject>
Log: <yes | no>
Notes: <some commentary if required>

In this model, if you want to describe HTTP access to a web server, you might write the following policy:

Source Interface: outside
Source IP Address: 0.0.0.0/0 (Any IP)
NAT Source IP Address: no
Destination Interface: inside
Destination IP Address: 192.0.2.2 (External IP)
NAT Destination IP Address: 198.51.100.2 (Internal IP)
Destination Port: tcp/80
Action: allow
Log: yes

So, without further waffling, let’s build a policy. By default all traffic will be logged. In high-traffic environments, you may wish to prevent certain traffic from being logged, but on the whole, I think you shouldn’t really lose firewall logs unless you need to!

Allowing established, related and same-host traffic

This rule is only really needed on iptables based firewalls, as all the commercial vendors (as far as I can tell, at least) already cover this as “standard”. If you’re using UFW (a wrapper to iptables), this rule is covered off already, but essentially it goes a bit like this:

Source Interface: lo (short for "local", where the traffic never leaves the device)
Source IP Address: any
NAT Source IP Address: no
Destination Interface: lo
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: any
Action: allow
Log: no
Notes: This above rule permits traffic between localhost addresses (127.0.0.0/8) or between public addresses on the same host, for example, between two processes without being blocked.
flags: Established OR Related
Action: allow
Log: no
Notes: This above rule is somewhat special, as it looks for specific flags on the packet, that says "If we've already got a session open, let it carry on talking".

Dropping Noisy Traffic

In a network, some proportion of the traffic is going to be “noisy”. Whether it’s broadcast traffic from your application that uses mDNS, or the Windows File Share trying to find like-minded hosts to exchange data… these can fill up your logs, so lets drop the broadcast and multicast IPv4 traffic, and not log them.

Source Interface: any
Source IP Address: 0.0.0.0/0
NAT Source IP Address: no
Destination Interface: any
Destination IP Address: 255.255.255.255 (global broadcast), 192.0.2.255 ("outside" broadcast), 198.51.100.255 ("inside" broadcast) and 224.0.0.0/4 (multicast)
NAT Destination IP Address: no
Destination Port: any
Action: deny
Log: no
Notes: The global and local broadcast addresses are used to "find" other hosts in a network, whether that's a DHCP server or something like mDNS. Dropping this prevents the traffic from appearing in your logs later.

Permitting Management Traffic

Typically you want to trust certain machines to access or be accessed by this host – whether it’s your SYSLOG collector, or the box that can manage the firewall policy, so here we’ll create a policy that lets these in.

Source Interface: inside
Source IP Address: 198.51.100.2 and 2001:db8:123d:abc::2 (Management IP)
NAT Source IP Address: no
Destination Interface: inside
Destination IP Address: 198.51.100.1 and 2001:db8:123d:abc::1 (Firewall IP)
NAT Destination IP Address: no
Destination Port: SSH (tcp/22)
Action: permit
Log: yes
Notes: Allow inbound SSH access. You're unlikely to need more inbound ports, but if you do - customise them here.
Source Interface: inside
Source IP Address: 198.51.100.1 and 2001:db8:123d:abc::1 (Firewall IP)
NAT Source IP Address: no
Destination Interface: inside
Destination IP Address: 198.51.100.2 and 2001:db8:123d:abc::2 (Management IP)
NAT Destination IP Address: no
Destination Port: SYSLOG (udp/514)
Action: permit
Log: yes
Notes: Allow outbound SYSLOG access. Tailor this to outbound ports you need.

Allowing Control Traffic

ICMP is a protocol that is fundamental to IPv4 and IPv6. Commonly used for Traceroute and Ping, but also used to perform REJECT responses and that sort of thing. We’re only going to let it be initiated *out* not in. Some people won’t allow this rule, or tailor it to more specific destinations.

Source Interface: inside
Source IP Address: any
NAT Source IP Address: 192.0.2.2 (The firewall IP address which may be replaced with 0.0.0.0 indicating "whatever IP address is bound to the outbound interface")
Destination Interface: outside
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: icmp
Action: allow
Log: yes
Notes: ICMPv4 and ICMPv6 are different things. This is just the ICMPv4 version. IPv4 does require NAT, hence the difference from the IPv6 version below.
Source Interface: inside
Source IP Address: any
NAT Source IP Address: no
Destination Interface: outside
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: icmpv6
Action: allow
Log: yes
Notes: ICMPv4 and ICMPv6 may be treated as different things. This is just the ICMPv6 version. IPv6 does not require NAT.

Protect the Firewall

There should be no other traffic going to the Firewall, so let’s drop everything. There are two types of “Deny” message – a “Reject” and a “Drop”. A Reject sends a message back from the host which is refusing the connection – usually the end server to say that the service didn’t want to reply to you, but if there’s a box in the middle – like a firewall – this reject (actually an ICMP packet) comes from the firewall instead. In this case it’s identifying that the firewall was refusing the connection for the node, so it advertises the fact the end server is protected by a security box. Instead, firewall administrators tend to use Drop, which just silently discards the initial request, leaving the initiating end to “Time Out”. You’re free to either “Reject” or “Drop” whenever we show “Deny” in the below policies, but bear it in mind that it’s less secure to use Reject than it is to Drop.

Source Interface: any
Source IP Address: any
NAT Source IP Address: no
Destination Interface: any
Destination IP Address: 192.0.2.2, 2001:db8:123c:abd::2, 198.51.100.1 and 2001:db8:123d:abc::1 (may also be represented as :: or 0.0.0.0 depending on the platform)
NAT Destination IP Address: no
Destination Port: any
Action: deny
Log: no
Notes: Drop everything targetted at the firewall IPs. If you have more NICs or additional IP addresses on the firewall, these will also need blocking.

“Normal” Inbound Traffic

After you’ve got your firewall protected, now you can sort out your “normal” traffic flows. I’m going to add a single inbound policy to represent the sort of traffic you might want to configure (in this case a simple web server), but bear in mind some environments don’t have any “inbound” rules (for example, most homes would be in this case), and some might need lots and lots of inbound rules. This is just to give you a flavour on what you might see here.

Source Interface: outside
Source IP Address: any
NAT Source IP Address: no
Destination Interface: inside
Destination IP Address: 192.0.2.2 (External IP)
NAT Destination IP Address: 198.51.100.2 (Internal IP)
Destination Port: tcp/80 (HTTP), tcp/443 (HTTPS)
Action: allow
Log: yes
Notes: This is the IPv4-only rule. Note a NAT MUST be applied here.
Source Interface: outside
Source IP Address: any
NAT Source IP Address: no
Destination Interface: inside
Destination IP Address: 2001:db8:123d:abc::2
NAT Destination IP Address: no
Destination Port: tcp/80 (HTTP), tcp/443 (HTTPS)
Action: allow
Log: yes
Notes: This is the IPv6-only rule. Note that NO NAT is required (but, you may wish to perform NAT, depending on your environment).

“Normal” Outbound Traffic

If you’re used to a DSL router, that basically just allows all outbound traffic. We’re going to implement that here. If you want to be more specific about things, you’d define your outbound rules like the inbound rules in the block above… but if you’re not that worried, then this rule below is generally going to be all OK :)

Source Interface: inside
Source IP Address: any
NAT Source IP Address: 192.0.2.2 (The firewall IP address which may be replaced with 0.0.0.0 indicating "whatever IP address is bound to the outbound interface")
Destination Interface: outside
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: any
Action: allow
Log: yes
Notes: This is just the IPv4 version. IPv4 does require NAT, hence the difference from the IPv6 version below.
Source Interface: inside
Source IP Address: any
NAT Source IP Address: no
Destination Interface: outside
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: any
Action: allow
Log: yes
Notes: This is just the IPv6 version. IPv6 does not require NAT.

Drop Rule

Following your permit rules above, you now need to drop everything else. Fortunately, by now, you’ve “white-listed” all the permitted traffic, so now we can just drop “everything”. So, let’s do that!

Source Interface: any
Source IP Address: any
NAT Source IP Address: no
Destination Interface: any
Destination IP Address: any
NAT Destination IP Address: no
Destination Port: any
Action: deny
Log: yes

And so that is a basic firewall policy… or at least, it’s the template I tend to stick to! :)

Expanding XFS drives with LVM

Say, for example, you’ve got a lovely CentOS VM (using XFS by default) which has a disk that isn’t quite big enough. Fair enough, your VM Hypervisor is sensible enough to resize that disk without question… How do you resize the XFS partition? Assuming you’ve got your disk mounted as /dev/sda, and you’ve got a boot volume as partition 1 and a root volume as partition 2 (the standard install model)

  1. parted /dev/sda resizepart 2 100%
  2. partprobe /dev/sda
  3. pvresize /dev/sda2
  4. lvextend /dev/centos/root /dev/sda2
  5. xfs_growfs /dev/mapper/centos-root
The graphical version of the steps above

Research via:

"www.GetIPv6.info decal" from Phil Wolff on Flickr

Hurricane Electric IPv6 Gateway on Raspbian for Raspberry Pi

NOTE: This article was replaced on 2019-03-12 by a github repository where I now use Vagrant instead of a Raspberry Pi, because I was having some power issues with my Raspberry Pi. Also, using this method means I can easily use an Ansible Playbook. The following config will still work(!) however I prefer this Vagrant/Ansible workflow for this, so won’t update this blog post any further.

Following an off-hand remark from a colleague at work, I decided I wanted to set up a Raspberry Pi as a Hurricane Electric IPv6 6in4 tunnel router. Most of the advice around (in particular, this post about setting up IPv6 on the Raspberry Pi Forums) related to earlier version of Raspbian, so I thought I’d bring it up-to-date.

I installed the latest available version of Raspbian Stretch Lite (2018-11-13) and transferred it to a MicroSD card. I added the file ssh to the boot volume and unmounted it. I then fitted it into my Raspberry Pi, and booted it. While it was booting, I set a static IPv4 address on my router (192.168.1.252) for the Raspberry Pi, so I knew what IP address it would be on my network.

I logged into my Hurricane Electric (HE) account at tunnelbroker.net and created a new tunnel, specifying my public IP address, and selecting my closest HE endpoint. When the new tunnel was created, I went to the “Example Configurations” tab, and selected “Debian/Ubuntu” from the list of available OS options. I copied this configuration into my clipboard.

I SSH’d into the Pi, and gave it a basic config (changed the password, expanded the disk, turned off “predictable network names”, etc) and then rebooted it.

After this was done, I created a file in /etc/network/interfaces.d/he-ipv6 and pasted in the config from the HE website. I had to change the “local” line from the public IP I’d provided HE with, to the real IP address of this box. Note that any public IPs (that is, not 192.168.x.x addresses) in the config files and settings I’ve noted refer to documentation addressing (TEST-NET-2 and the IPv6 documentation address ranges)

auto he-ipv6
iface he-ipv6 inet6 v4tunnel
        address 2001:db8:123c:abd::2
        netmask 64
        endpoint 198.51.100.100
        local 192.168.1.252
        ttl 255
        gateway 2001:db8:123c:abd::1

Next, I created a file in /etc/network/interfaces.d/eth0 and put the following configuration in, using the first IPv6 address in the “routed /64” range listed on the HE site:

auto eth0
iface eth0 inet static
    address 192.168.1.252
    gateway 192.168.1.254
    netmask 24
    dns-nameserver 8.8.8.8
    dns-nameserver 8.8.4.4

iface eth0 inet6 static
    address 2001:db8:123d:abc::1
    netmask 64

Next, I disabled the DHCPd service by issuing systemctl stop dhcpcd.service Late edit (2019-01-22): Note, a colleague mentioned that this should have actually been systemctl stop dhcpcd.service && systemctl disable dhcpcd.service – good spot! Thanks!! This ensures that if, for some crazy reason, the router stops offering the right DHCP address to me, I can still access this box on this IP. Huzzah!

I accessed another host which had IPv6 access, and performed both a ping and an SSH attempt. Both worked. Fab. However, this now needs to be blocked, as we shouldn’t permit anything to be visible downstream from this gateway.

I’m using the Uncomplicated Firewall (ufw) which is a simple wrapper around IPTables. Let’s create our policy.

# First install the software
sudo apt update && sudo apt install ufw -y

# Permits inbound IPv4 SSH to this host - which should be internal only. 
# These rules allow tailored access in to our managed services
ufw allow in on eth0 app DNS
ufw allow in on eth0 app OpenSSH

# These rules accept all broadcast and multicast traffic
ufw allow in on eth0 to 224.0.0.0/4 # Multicast addresses
ufw allow in on eth0 to 255.255.255.255 # Global broadcast
ufw allow in on eth0 to 192.168.1.255 # Local broadcast

# Alternatively, accept everything coming in on eth0
# If you do this one, you don't need the lines above
ufw allow in on eth0

# Setup the default rules - deny inbound and routed, permit outbound
ufw default deny incoming 
ufw default deny routed
ufw default allow outgoing

# Prevent inbound IPv6 to the network
# Also, log any drops so we can spot them if we have an issue
ufw route deny log from ::/0 to 2001:db8:123d:abc::/64

# Permit outbound IPv6 from the network
ufw route allow from 2001:db8:123d:abc::/64

# Start the firewall!
ufw enable

# Check the policy
ufw status verbose
ufw status numbered

Most of the documentation I found suggested running radvd for IPv6 address allocation. This basically just allocates on a random basis, and, as far as I can make out, each renewal gives the host a new IPv6 address. To make that work, I performed apt-get update && apt-get install radvd -y and then created this file as /etc/radvd.conf. If all you want is a floating IP address with no static assignment – this will do it…

interface eth0
{
    AdvSendAdvert on;
    MinRtrAdvInterval 3;
    MaxRtrAdvInterval 10;
    prefix 2001:db8:123d:abc::/64
    {
        AdvOnLink on;
        AdvAutonomous on;
    };
   route ::/0 {
   };
};

However, this doesn’t give me the ability to statically assign IPv6 addresses to hosts. I found that a different IPv6 allocation method will do static addressing, based on your MAC address called SLAAC (note there are some privacy issues with this, but I’m OK with them for now…) In this mode assuming the prefix as before – 2001:db8:123d:abc:: and a MAC address of de:ad:be:ef:01:23, your IPv6 address will be something like: 2001:db8:123d:abc:dead:beff:feef:0123and this will be repeatably so – because you’re unlikely to change your MAC address (hopefully!!).

This SLAAC allocation mode is available in DNSMasq, which I’ve consumed before (in a Pi-Hole). To use this, I installed DNSMasq with apt-get update && apt-get install dnsmasq -y and then configured it as follows:

interface=eth0
listen-address=127.0.0.1
# DHCPv6 - Hurricane Electric Resolver and Google's
dhcp-option=option6:dns-server,[2001:470:20::2],[2001:4860:4860::8888]
# IPv6 DHCP scope
dhcp-range=2001:db8:123d:abc::, slaac

I decided to move from using my router as a DHCP server, to using this same host, so expanded that config as follows, based on several posts, but mostly centred around the MAN page (I’m happy to have this DNSMasq config improved if you’ve got any suggestions ;) )

# Stuff for DNS resolution
domain-needed
bogus-priv
no-resolv
filterwin2k
expand-hosts
domain=localnet
local=/localnet/
log-queries

# Global options
interface=eth0
listen-address=127.0.0.1

# Set these hosts as the DNS server for your network
# Hurricane Electric and Google
dhcp-option=option6:dns-server,[2001:470:20::2],2001:4860:4860::8888]

# My DNS servers are:
server=1.1.1.1                # Cloudflare's DNS server
server=8.8.8.8                # Google's DNS server

# IPv4 DHCP scope
dhcp-range=192.168.1.10,192.168.1.210,12h
# IPv6 DHCP scope
dhcp-range=2001:db8:123d:abc::, slaac

# Record the DHCP leases here
dhcp-leasefile=/run/dnsmasq/dhcp-lease

# DHCPv4 Router
dhcp-option=3,192.168.1.254

So, that’s what I’m doing now! Hope it helps you!

Late edit (2019-01-22): In issue 129 of the “Awesome Self Hosted Newsletter“, I found a post called “My New Years Resolution: Learn IPv6“… which uses a pfSense box and a Hurricane Electric tunnel too. Fab!

Header image is “www.GetIPv6.info decal” by “Phil Wolff” on Flickr and is released under a CC-BY-SA license. Used with thanks!

"Zenith Z-19 Terminal" from ajmexico on Flickr

Some things I learned this week while coding extensions to Ansible!

If you follow any of the content I post around the internet, you might have seen me asking questions about trying to get data out of azure_rm_*_facts into something that’s usable. I can’t go into why I needed that data yet (it’s a little project I’m working on), but the upshot is that trying to manipulate data using “set_fact” with jinja is *doable* but *messy*. In the end, I decided to hand it all off to a new ansible module I’m writing. So, here are the things I learned about this.

  1. There’s lots more documentation about writing a module (a plugin that let’s you do stuff) than there is about writing filters (things that change text inline) or lookups (things that let you search other data stores). In the end, while I could have spent the time to figure out how better to write a filter or a lookup, it actually makes more sense in my context to hand a module all my data, and say “Parse this” and register the result than it would have done to have the playbook constantly check whether things were in other things. I still might have to do that, but… you know, for now, I’ve got the bits I want! :)
  2. I did start looking at writing a filter, and discovered that the “debugging advice” on the ansible site is all geared up to enable more modules than enabling filters… but I did discover that modules execute on their target (e.g. WebHost01) while filters and lookups execute on the local machine. Why does this matter? Well…..
  3. While I was looking for documentation about debugging Ansible code, I stumbled over this page on debugging modules that makes it all look easy. Except, it’s only for debugging *MODULES* (very frustrating. Well, what does it actually mean? The modules get zipped up and sent to the host that will be executing the code, which means that with an extra flag to your playbook (ANSIBLE_KEEP_REMOTE_FILES – even if it’s going to be run on “localhost”), you get the combined output of the script placed into a path on your machine, which means you can debug that specific play. That doesn’t work for filters…
  4. SOO, I jumped into #ansible on Freenode and asked for help. They in turn couldn’t help me (it’s more about writing playbooks than writing filters, modules, etc), so they directed me to #ansible-devel, where I was advised to use a python library called “q” (Edit, same day: my friend @mohclips pointed me to this youtube video from 2003 of the guy who wrote q explaining about it. Thanks Nick! I learned something *else* about this library).
  5. Oh man, this is the motherlode. So, q makes life *VERY* easy. Assuming this is valid code: All you’d need to do would be to add two lines, as you’ll see here: This then dumps the output from each of the q(something) lines into /tmp/q for you to read at your leisure! (To be fair, I’d probably remove it after you’ve finished, so you don’t fill a disk :) )
  6. And that’s when I discovered that it’s actually easier to use q() for all my python debugging purposes than it is to follow the advice above about debugging modules. Yehr, it’s basically a load of print statements, so you don’t get to see stack traces, or read all the variables, and you don’t get to step through code to see why decisions were taken… but for the rubbish code I produce, it’s easily enough for me!

Header image is “Zenith Z-19 Terminal” by “ajmexico” on Flickr and is released under a CC-BY license. Used with thanks!

"LEGO Factory Playset" from Brickset on Flickr

Building Azure Environments in Ansible

Recently, I’ve been migrating my POV (proof of value) and POC (proof of concept) environment from K5 to Azure to be able to test vendor products inside Azure. I ran a few tests to build the environment using the native tools (the powershell scripts) and found that the Powershell way of delivering Azure environments seems overly complicated… particularly as I’m comfortable with how Ansible works.

To be fair, I also need to look at Terraform, but that isn’t what I’m looking at today :)

So, let’s start with the scaffolding. Any Ansible Playbook which deals with creating virtual machines needs to have some extra modules installed. Make sure you’ve got ansible 2.7 or later and the python azure library 2.0.0 or later (you can get both with pip for python).

Next, let’s look at the group_vars for this playbook.

This file has several pieces. We define the project settings (anything prefixed project_ is a project setting), including the prefix used for all resources we create (in this case “env01“), and a standard password used for all VMs we create (in this case “My$uper$ecret$Passw0rd“).

Next we define the standard images to load from the Marketplace. You can extend this with other images, these are just the “easiest” ones that I’m most familiar with (your mileage may vary). Next up is the networks to build inside the VNet, and lastly we define the actual machines we want to build. If you’ve got questions about any of the values we define here, just let me know in the comments below :)

Next, we’ll start looking at the playbook (this has been exploded out – the full playbook is also in the gist).

Here we start by pulling in the variables we might want to override, and we do this by reading system environment variables (ANSIBLE_PREFIX and BREAKGLASS) and using them if they’re set. If they’re not, use the project defaults, and if that hasn’t been set, use some pre-defined values… and then tell us what they are when we’re running the tasks (those are the debug: lines).

This block is where we create our “Static Assets” – individual items that we will be consuming later. This shows a clear win here over the Powershell methods endorsed by Microsoft – here you can create a Resource Group (RG) as part of the playbook! We also create a single Storage Account for this RG and a single VNET too.

These creation rules are not suitable for production use, as this defines an “Any-Any” Security group! You should tailor your security groups for your need, not for blanket access in!

This is where things start to get a bit more interesting – We’re using the “async/async_status” pattern here (and the rest of these sections) to start creating the resources in parallel. As far as I can tell, sometimes you’ll get a case where the async doesn’t quite get set up fast enough, then the async_status can’t track the resources properly, but re-running the playbook should be enough to sort that out, without slowing things down too much.

But what are we actually doing with this block of code? A UDR is a “User Defined Route” or routing table for Azure. Effectively, you treat each network interface as being plumbed directly to the router (none of this “same subnet broadcast” stuff works here!) so you can do routing at the router for all the networks.

By default there are some existing network routes (stuff to the internet flows to the internet, RFC1918 addresses are dropped with the exception of any RFC1918 addresses you have covered in your VNETs, and each of your subnets can reach each other “directly”). Adding a UDR overrides this routing table. The UDRs we’re creating here are applied at a subnet level, but currently don’t override any of the existing routes (they’re blank). We’ll start putting routes in after we’ve added the UDRs to the subnets. Talking of which….

Again, this block is not really suitable for production use, and assumes the VNET supernet of /8 will be broken down into several /24’s. In the “real world” you might deliver a handful of /26’s in a /24 VNET… or you might even have lots of disparate /24’s in the VNET which are then allocated exactly as individual /24 subnets… this is not what this model delivers but you might wish to investigate further!

Now that we’ve created our subnets, we can start adding the routing table to the UDR. This is a basic one – add a 0.0.0.0/0 route (internet access) from the “protected” network via the firewall. You can get a lot more specific than this – most people are likely to want to add the VNET range (in this case 10.0.0.0/8) via the firewall as well, except for this subnet (because otherwise, for example, 10.0.0.100 trying to reach 10.0.0.101 will go via the firewall too).

Without going too much into the intricacies of network architecture, if you are routing your traffic between subnets to the firewall, it’s probably better to get an appliance with more interfaces, so you can route traffic across the appliance, rather than going across a single interface as this will halve your traffic bandwidth (it’s currently capped 1Gb/s – so 500Mb/s).

Having mentioned “The Internet” – let’s give our firewall a public IP address, and create the rest of the interfaces as well.

This script creates a public IP address by default for each interface unless you explicitly tell it not to (see lines 40, 53 and 62 in the group_vars file I rendered above). You could easily turn this around by changing the lines which contain this:

item.1.public is not defined or (item.1.public is defined and item.1.public == 'true')

into lines which contain this:

item.1.public is defined and item.1.public == 'true'

OK, having done all that, we’re now ready to build our virtual machines. I’ve introduced a “Priority system” here – VMs with priority 0 go first, then 1, and 2 go last. The code snippet below is just for priority 0, but you can easily see how you’d extrapolate that out (and in fact, the full code sample does just that).

There are a few blocks here to draw attention to :) I’ve re-jigged them a bit here so it’s clearer to understand, but when you see them in the main playbook they’re a bit more compact. Let’s start with looking at the Network Interfaces section!

network_interfaces: |
  [
    {%- for nw in item.value.ports -%}
      '{{ prefix }}{{ item.value.name }}port{{ nw.subnet.name }}'
      {%- if not loop.last -%}, {%- endif -%} 
    {%- endfor -%}
  ]

In this part, we loop over the ports defined for the virtual machine. This is because one device may have 1 interface, or four interfaces. YAML is parsed to make a JSON variable, so here we can create a JSON variable, that when the YAML is parsed it will just drop in. We’ve previously created all the interfaces to have names like this PREFIXhostnamePORTsubnetname (or aFW01portWAN in more conventional terms), so here we construct a JSON array, like this: ['aFW01portWAN'] but that could just as easily have been ['aFW01portWAN', 'aFW01portProtect', 'aFW01portMGMT', 'aFW01portSync']. This will then attach those interfaces to the virtual machine.

Next up, custom_data. This section is sometimes known externally as userdata or config_disk. My code has always referred to it as a “Provision Script” – hence the variable name in the code below!

custom_data: |
  {%- if item.value.provision_script is defined and item.value.provision_script != '' -%}
    {%- include(item.value.provision_script) -%}
  {%- elif item.value.image.provision_script is defined and item.value.image.provision_script != '' -%}
    {%- include(item.value.image.provision_script) -%}
  {%- else -%}
    {{ omit }}
  {%- endif -%}

Let’s pick this one apart too. If we’ve defined a provisioning script file for the VM, include it, if we’ve defined a provisioning script file for the image (or marketplace entry), then include that instead… otherwise, pretend that there’s no “custom_data” field before you submit this to Azure.

One last quirk to Azure, is that some images require a “plan” to go with it, and others don’t.

plan: |
  {%- if item.value.image.plan is not defined -%}{{ omit }}{%- else -%}
    {'name': '{{ item.value.image.sku }}',
     'publisher': '{{ item.value.image.publisher }}',
     'product': '{{ item.value.image.offer }}'
    }
  {%- endif -%}

So, here we say “if we’ve not got a plan, omit the value being passed to Azure, otherwise use these fields we previously specified. Weird huh?

The very last thing we do in the script is to re-render the standard password we’ve used for all these builds, so that we can check them out!

Want to review this all in one place?

Here’s the link to the full playbook, as well as the group variables (which should be in ./group_vars/all.yml) and two sample userdata files (which should be in ./userdata) for an Ubuntu machine (using cloud-init) and one for a FortiGate Firewall.

All the other files in that gist (prefixes from 10-16 and 00) are for this blog post only, and aren’t likely to work!

If you do end up using this, please drop me a note below, or star the gist! That’d be awesome!!

Image credit: “Lego Factory Playset” from Flickr by “Brickset” released under a CC-BY license. Used with Thanks!

Picture of a bull from an 1882 reference guide, as found on Flickr

Abattoir Architecture for Evergreen – using the Pets versus Cattle parable

Work very generously sent me on a training course today about a cloud based technology we’re considering deploying.

During the course, the organiser threw a question to the audience about “who can explain what a container does?” and a small number of us ended up talking about Docker (primarily for Linux) and CGroups, and this then turned into a conversation about the exceedingly high rate of changes deployed by Amazon, Etsy and others who have completely embraced microservices and efficient CI/CD pipelines… and then I mentioned the parable of Pets versus Cattle.

The link above points to where the story comes from, but the short version is…

When you get a pet, it comes as a something like a puppy or kitten, you name it, you nurture it, bring it up to live in your household, and when it gets sick, because you’ve made it part of your family, you bring in a vet who nurses it back to health.

When you have cattle, it doesn’t have a name, it has a number, and if it gets sick, you isolate it from the herd and if it doesn’t get better, you take it out back and shoot it, and get a new one.

A large number of the audience either hadn’t heard of the parable, or if they had, hadn’t heard it delivered like this.

We later went on to discuss how this applies in a practical sense, not just in docker or kubernetes containers, but how it could be applied to Infrastructure as a Service (IaaS), even down to things like vendor supplied virtual firewalls where you have Infrastructure as Code (IaC).

If, in your environment, you have some service you treat like cattle – perhaps a cluster of firewalls behind a load balancer or a floating IP address and you need to upgrade it (because it isn’t well, or it’s not had the latest set of policy deployed to it). You don’t amend the policy on the boxes in question… No! You stand up a new service using your IaC with the latest policy deployed upon it, and then you would test it (to make sure it’s stood up right), and then once you’re happy it’s ready, you transition your service to the new nodes. Once the connections have drained from your old nodes, you take them out and shoot them.

Or, if you want this in pictures…

Stage 1 - Before the new service deployment
Stage 1 – Before the new service deployment
Stage 2 - The new service deployment is built and tested
Stage 2 – The new service deployment is built and tested
Stage 3 - Service transitions to the new service deployment
Stage 3 – Service transitions to the new service deployment
Stage 4 - The old service is demised, and any resources (including licenses) return to the pool
Stage 4 – The old service is demised, and any resources (including licenses) return to the pool

I was advised (by a very enthusiastic Mike until he realised that I intended to follow through with it) that the name for this should be as per the title. So, the next time someone asks me to explain how they could deploy, I’ll suggest they look for the Abattoir in my blog, because, you know, that’s normal, right? :)

Image credit: Image from page 255 of “Breeder and sportsman” (1882) via Internet Archive Book Image on Flickr

Troubleshooting FortiGate API issues with the CLI?

One of my colleagues has asked me for some help with an Ansible script he’s writing to push some policy to a cloud hosted FortiGate appliance. Unfortunately, he kept getting some very weird error messages, like this one:

fatal: [localhost]: FAILED! => {"changed": false, "meta": {"build": 200, "error": -651, "http_method": "PUT", "http_status": 500, "mkey": "vip8080", "name": "vip", "path": "firewall", "revision": "36.0.0.10745196634707694665.1544442857", "serial": "CENSORED", "status": "error", "vdom": "root", "version": "v6.0.3"}, "msg": "Error in repo"}

This is using Fortinet’s own Ansible Modules, which, in turn use the fortiosapi python module.

This same colleague came across a post on the Fortinet Developer Network site (access to the site requires vendor approval), which said “this might be an internal bug, but to debug it, use the following”

fgt # diagnose debug enable

fgt # diagnose debug cli 8
Debug messages will be on for 30 minutes.

And then run your API commands. Your error message will be surfaced there… so here’s mine! (Mapped port doesn’t match extport in a vip).

0: config firewall vip
0: edit "vip8080"
0: unset src-filter
0: unset service
0: set extintf "port1"
0: set portforward enable
0: unset srcintf-filter
0: set mappedip "192.0.2.1-192.0.2.1"
0: unset extport
0: set extport 8080-8081
0: unset mappedport
0: set mappedport 8080
-651: end