Round-robin DNS – another use for ANAMEs

March 22nd, 2019 by

Sensible people don’t like to hard code IP addresses in lots of different places in DNS. Better to assign it a name, and then reference that name, as it makes it clearer what’s what and if you ever need to change that IP, you’ve only got to do it one place.

CNAME records can be a good way to do this, by aliasing a DNS name to an IP. Unfortunately, the DNS specs prevent you using CNAMEs in various places that you might want to, most commonly at the root-level of your domain (the dreaded “CNAME and other data” problem).

This is where ANAME pseudo-records come in. They look just like a CNAME record, but rather than being added to the DNS, our server converts them into A and AAAA records. This allows you to get the benefits of a CNAME in places where a CNAME is not legal.

This week a customer suggested another use for ANAME records that we’d not previously thought of: round robin DNS. That is, a single DNS name that points to multiple servers. As you can’t have multiple CNAME records for the same hostname, implementing round-robin DNS means hard-coding A and AAAA records into your zone file. Like this:

proxy.mythic-beasts.com. 3600	IN	A	93.93.129.174
proxy.mythic-beasts.com. 3600	IN	A	46.235.225.189
proxy.mythic-beasts.com. 3600	IN	AAAA	2a00:1098:0:80:1000:3b:1:1
proxy.mythic-beasts.com. 3600	IN	AAAA	2a00:1098:0:82:1000:3b:1:1

Which is messy. Wouldn’t it be nicer to use the names of the servers involved? Like this:

proxy.mythic-beasts.com. 3600	IN	CNAME	 rproxy46-sov-a.mythic-beasts.com.
proxy.mythic-beasts.com. 3600	IN	CNAME    rproxy46-hex-a.mythic-beasts.com.

Sadly, the spec says you can’t do that, but thanks to a minor tweak to our DNS control panel code, you can now do it with ANAME records. Simply specify multiple ANAME records for your host name, and we’ll go and find all A and AAAA records for all of the hosts that are referenced.

Thanks to @grayvsearth for the suggestion on this one.

ANAME records are available in our DNS management interface, which is included with all domain registrations, and available for free on other domains for customers of other services. Other features include a DNS API, allowing you to obtain Wildcard Let’s Encrypt certificates.

Let’s Encrypt wildcard certificates

February 15th, 2019 by

Wildcard… sounds a bit like wildcat… cat pics!
Photo by Peter Trimming, CC BY 2.0

We’ve just made some changes to our plugin for dehydrated in order to better support Let’s Encrypt wildcard certificates.

Unlike normal certificates, which can be obtained using a web-based challenge, Let’s Encrypt’s wildcard certificates require a DNS-based challenge. In other words, you need to prove that you can control the DNS for the domain for which you are requesting a wildcard certificate.

Mythic Beasts provides a simple API for controlling DNS, which makes it possible to automate the process of responding to these challenges, and we provide a plugin for the popular dehydrated client that does just this.

We’ve just deployed a minor change which means that it’s now possible to obtain a single certificate for a domain, and a wildcard under that domain.

Access to our DNS API is included with all domain registrations. For more information, please see our instructions on using DNS-based challenges wih Let’s Encrypt. Please note that in order to obtain wildcard certificates you need to be using dehydrated version 0.6.0 or later.

Mythic Beasts acquires VMHaus

November 26th, 2018 by

Our pet wyvern was hungry again.

We’re pleased to announce that Mythic Beasts has acquired VMHaus, a virtual server provider with facilities in London and Los Angeles. We will continue to run VMHaus as a separate brand selling low-cost, prepaid virtual servers, which we believe will complement our own virtual server products well. We’re also pleased to announce that VMHaus co-founder Basil Fillan has joined Mythic Beasts as a full time employee. Basil has been responsible for the development of the VMHaus technical infrastructure, and will be ideally placed to help us provide support to VMHaus customers.

In the short term, VMHaus customers will see no changes to their services. Payments and invoicing will continue to be through VMHaus Ltd, and we will continue to accept new orders for VMHaus products. In the medium term, we’re planning improvements to both the VMHaus platform and our own virtual server infrastructure, based on our combined experiences of developing the two systems.

On the VMHaus side we hope to be able to start selling virtual servers in Amsterdam early in the new year, and also be able to offer IPv6-only virtual servers at a discounted rate. VMHaus customers will also be able to take advantage of our other services such as domain registration and backups.

On the Mythic Beasts side, we expect to be able to offer service upgrades thanks to the economies of scale resulting from the acquisitions of VMHaus and of BHost this summer.

OpenWRT install to RAM – run iftop on a router with very limited flash

November 23rd, 2018 by

OpenWRT is awesome, as it allows you to run proper Linux tools on your home router. I’m currently using a very old, underspecced TP Link box, with 32MB of RAM, but just 4MB of flash storage. This is just enough to get what I need installed, but one thing I’ve always wanted to do is use iftop to quickly see what’s using all the bandwidth. Unfortunately iftop, with its dependencies on libpcap and libncurses, just won’t fit into a 4MB image.

I recently stumbled across opkg’s install-to-RAM option, allowing me to use the 32MB of RAM to install the package, with the minor and obvious downside that it gets uninstalled when the router gets rebooted. For something like iftop, which is used for ad-hoc diagnostics, this isn’t a big issue.

Installing to RAM puts the packages under /tmp, so a little effort is required to make sure that libraries and other resources can be found. I now have the following shell script which installs iftop if it isn’t already, sets some environment variables and invokes iftop:

#!/bin/sh

if [ ! -f /tmp/usr/bin/iftop ] ; then
  opkg update
  opkg install -d ram iftop
fi

export LD_LIBRARY_PATH=/tmp/usr/lib
export TERM=xterm
export TERMINFO=/tmp/usr/share/terminfo/

/tmp/usr/bin/iftop $@

Fortunately I do have enough free space on flash storage to store the above script.
Obviously a similar approach could be used with other packages that are only needed “on demand”.

Let’s Encrypt, Dehydrated, Curl and redirects

March 15th, 2018 by

We use Let’s Encrypt for SSL certificates, and our preferred client for obtaining certificates is the simple but effective dehydrated shell script, not least because it’s packaged for Debian.

On Sunday, we started getting some alerts relating to a failure to automatically re-issue Let’s Encrypt certificates. A quick bit of digging yielded this error:

+ Creating fullchain.pem…
  + ERROR: An error occurred while sending get-request to http://cert.int-x3.letsencrypt.org/ (Status 301)

Let’s Encrypt have started including an HTTP redirect as part of the certificate issue process and dehydrated doesn’t pass the necessary option to curl to follow the redirect. This can be fixed by patching dehydrated (and a packaged fix for Debian Stretch is now available via Debian backports), but it can also be solved with a simple config change:

echo 'CURL_OPTS="-L"' > /etc/dehydrated/conf.d/curl.sh

Naturally, customers of our managed hosting services and customers using the free HTTPS option on our hosting accounts need not worry about this issue. Our managed hosting includes monitoring all HTTPS websites for certificates nearing expiry, so we become aware of any issues well before your users do.

Chrome to brand non-HTTPS sites as “insecure” – time to click the button

February 12th, 2018 by

As reported by The Register, sites which do not use HTTPS will soon be actively labelled as “insecure” by the Chrome browser. HTTPS is the secure form of HTTP that makes the little green padlock appear in browsers.

Ultimately, sites which use HTTP are going to be labelled like this:

Example of HTTP site labelled as "not secure"

Not subtle, eh?

The Reg article suggests that initial changes will be deployed July 2018, and will be a little more subtle, but with Chrome having 55-60% market share, it really is time to switch your website to HTTPS.

Fortunately, if you’re hosted with Mythic Beasts this is really easy.¬† All of our hosting accounts include free SSL (aka TLS) certificates (provided by Let’s Encrypt), and you can enable HTTPS hosting by just clicking a button in the control panel.¬† Here’s how:

Enabling HTTPS for your Mythic Beasts-hosted website

First, log in to our customer control panel, click on “Hosting and shell accounts”, and click through to the hosting account for your site.¬† Now find your site in the list, and click on “web settings”:

If you have both a “www” prefixed and bare version, as above, you’ll want to do both.¬†

On the web settings page, scroll down to the “security” section:

Screen shot of security settingsYou almost certainly want the third option: this will enable HTTPS hosting, and ensure that users see the secure version of the site by default.¬† (Once you’re happy that your HTTPS site is working exactly as you want it, you could consider switching to the fourth option).

Click, hit “save changes”:

Screenshot of "changes saved" messageWe’ve got plans to make this faster, but for the moment, you’ll need to wait a few minutes.¬† We’ll go and obtain a certificate for your site, and once installed update your site so that it redirects to the HTTPS by default.

Screenshot of HTTPS location bar

Bingo!

If you haven’t got a working HTTPS site within 10 minutes, email us¬†– we’re here to help.

Any gotchas?

The instructions here will only work if the HTTP version of your site is hosted by Mythic Beasts.¬† ¬†If you’re configuring a new site with Mythic Beasts, make sure that you can access your site via HTTP before enabling HTTPS.

If you’re transferring a site to us that is already using HTTPS, please see our transfer in instructions for how to do this with an interruption to service.

Managed hosting

We’ve been deploying HTTPS as the default for customers of our managed services for some time. We’re going to be doing an audit of all managed sites to warn customers of this upcoming change, but in the meantime, if you’re a managed customer with an http site, just email us and we’ll sort it out.

Domain price reductions

February 9th, 2018 by

Fortunately we don’t buy domains in Bitcoin

Most of our domains are billed to us in US Dollars, so our pricing is at the mercy of the GBP/USD exchange rate.¬† The pound has strengthened significantly against the dollar since we last reviewed our pricing, so we’ve just rolled out reductions on many of our domain registration prices.¬† For example, .com domains drop by ¬£2 to ¬£11 + VAT, and¬†.cymru (which, confusingly, we buy in dollars)¬†drops by ¬£3.50 to ¬£22.

We aim to offer straightforward, no-nonsense pricing with no unsustainable introductory discounts that punish customer loyalty with inflated prices in subsequent years.  We price our domains at a level that allows us to properly support our customers.

 

Sender Rewriting Scheme

October 30th, 2017 by

tl;dr: SRS changes the sender address when you forward email so it doesn’t get filed as spam.

We’ve just deployed an update to our hosting accounts that allows you to enable Sender Rewriting Scheme when forwarding mail for your domain.

We’ve previously mentioned how we’re seeing increased adoption of Sender Policy Framework (SPF), a system for ensuring that mail from a domain only comes from authorised servers. Whilst this may or may not reduce spam, it does very reliably break email forwarding.

If someone at sender.com sends you an email to you at yourdomain.com and you forward it on to your address at youremailprovider.com, the email that arrives at your final address will come from the mail server hosting yourdomain.com which almost certainly isn’t listed as a valid sender in the SPF record for sender.com.¬† Your email provider may reject the mail, or flag it as “untrusted”.

To fix this, we need a different TLA: SRS, or Sender Rewriting Scheme. As the name suggests, this rewrites the sender address of a forwarded email, from one in a domain that you don’t control (sender.com) to one that you do (yourdomain.com).

In the example above, the actual rewritten address would be something like:

SRS0-9oge=B5=sender.com=them@yourdomain.com

This includes an encoded version of the original address, and any email sent to it will be routed back to the sender.  This means that any bounces messages will end up in the right place.

The sender and recipient in these examples refer to the “envelope” sender and receiver.¬† The addresses that are normally visible to users are the “from” and “to” headers, which may be different and are unaffected by sender rewriting.¬† Applying SRS should be invisible to the end users.

SRS is now available as an option whenever you create or edit a forwarder using the customer control panel for email accounts hosted on our main hosting servers.  If your account is hosted on sphinx, we need to do a little extra magic to enable it, so please email support.

CAA records

September 1st, 2017 by

A handful of the hundreds of different organisations, all of whom must be trustworthy.

Everybody knows that SSL is a good idea. It secures communications. At the heart of SSL is a list of certificate authorities. These are organisations that the confirm the identity of the SSL certificate. For example, if GeoTrust says that Raspberry Pi is Raspberry Pi we know that we’re talking to the right site and our communications aren’t being sniffed.

However, the list of certificate authorities is large and growing and as it stands, you’ve got to trust all of them to only issue certificates to the right people. Of course, through incompetence or malice, they can make mistakes.

CAA records are a relatively new mechanism that aims to stop this happening, making it harder to impersonate secure organisations, execute bank robberies and steal peoples’ identities.



CAA records enable you to list in your domain’s DNS the certificate authorities that are allowed to issue certificates for your domain. So, Google has a record stating that only Google and Symantec are allowed to issue certificates for google.com. If someone manages to persuade Comodo they are Google and should be issued a google.com certificate, Comodo will be obliged to reject the request based on the CAA records.

Of course, in order to be of any use, you need to be able to trust the DNS records. Fortunately, these days we have DNSSEC (dns security).

How does it work?

A typical CAA record looks something like this:

example.com. IN CAA 3600 0 issue "letsencrypt.org"

This states that only Let’s Encrypt may issue certificates for example.com or its subdomains, such as www.example.com.

Going through each part in turn:

  • example.com – the name of the hostname to which the record apply. In our DNS interface, you can use a hostname of “@” to refer to your domain.
  • IN CAA – the record type.
  • 3600 – the “time to live” (TTL). The amount of time, in seconds, for which this record may be cached.
  • 0 – any CAA flags
  • issue– the type of property defined by this record (see below)
  • "letsencrypt.org" – the value of the property

At present, there are three defined property types:

  • issue – specifies which authorities may issue certificates of any type for this hostname
  • issuewild – specifies which authorities may issue wildcard certificates for this hostname
  • iodef – provides a URL for authorities to contact in the event of an attempt to issue an unauthorised certificate

CAA records can be added using the new section at the bottom of the DNS management page in our control panel:

The @ in the first field denotes a record that applies to the domain itself.

At Mythic Beasts, we’re a bit skeptical about the value of CAA records. In order to protect against the incompetence of CAs, they rely on CAs competently checking the CAA records before issuing certificates. That said, they do provide a straightforward check that CAs can build into their automated processes to detect and reject unauthorised requests, so publishing CAA records will raise the bar somewhat for anyone looking to fraudulently obtain a certificate for your domain.

One click HTTPS + HSTS

March 27th, 2017 by

Last year we rolled out one-click HTTPS hosting¬†for our hosting accounts using free Let’s Encrypt certificates. ¬†We’ve been making some further improvements to our control panel so that once you have enabled and tested HTTPS hosting, it’s also easy to redirect all HTTP traffic to your HTTPS site.

We’ve also added an option to enable¬†HTTP Strict Transport Security (HSTS). ¬†This allows you to use HTTPS on your website and commit that you’re not going to stop using it any time soon (we use 14 days by default). ¬†Once a user has visited your site their browser will cache the redirect from HTTP to HTTPS and will automatically redirect any future requests without even visiting the HTTP version of your site.

HSTS makes it harder for an attacker to impersonate your site as even if they can intercept your traffic, they won’t be able to present an non-HTTPS version of your site to any user that has visited your site within the last 14 days.

HTTPS and HSTS control panel settings

We believe that the web should be secure by default, and hope that these latest changes will make it that little bit easier to secure your website. ¬†These features are available on all of our web and email hosting accounts. ¬†We’ll also happily enable this as part of the service for customer of our managed server hosting.