Linux for switches

September 14th, 2015 by

For a long time at Mythic Beasts we’ve had a fairly healthy dislike for managed switches. The configuration method of switches is akin to a database with auto-commit on every command – you can’t batch a series of configuration changes into an atomic update. This means that you not only need to think about your starting and end configurations, but you also need to think about all the intermediate configuration too and make sure you don’t accidentally explode everything with an unexpected switch loop. Switches are also expensive and it’s always rankled that we’re paying a lot of money in order to use a network operating system that’s user unfriendly. Some of them are often less stable than the servers they connect to and they seem to manage excellent vendor lock-in – there is no end of advice that you can’t plug standards compatible switches from different manufacturers into each other because you risk inter-operability issues.

We’ve recently started trying Linux switches — commodity switches running Cumulus Linux.

Cumulus Linux makes your switch appear like a standard-ish debian server, with a lot of NICs.
The interfaces on our “1G” model are:

eth0 management interface
swp1 – swp48 1G switch ports
swp49 – swp52 10G switch ports

The switch is configured via /etc/network/interfaces, and uses bridges, VLANs and bonds to set up the configuration.

Linux has lots of advantages as a switch operating system. For a start if you need to patch ssh, under linux you download a replacement digitally signed openssh package and restart the process, on a traditional switch you download a whole new firmware over insecure tftp and reboot the switch – unlucky for the people connected to the switch.

The first obvious difference when configuring these switches is that by default, the switch doesn’t switch any traffic until some configuration is put in.

We can set up a simple network:

 # The primary network interface
 auto eth0
 iface eth0 inet static
        address xxx
        gateway xxx

 auto br0
 iface br0
         bridge-ports glob swp1-48
         bridge-stp on
         setmcsnoop 0

 auto br1
 iface br1
         bridge-ports glob swp49-52
         bridge-stp on
         setmcsnoop 0

This sets up the 1G ports (1-48) as a single VLAN, the 10G ports (49-52) as second VLAN, a management interface on the management port (eth0).

In this case we have an uplink on port 48 to a different network. So to migrate the uplink from our 1G network to our 10G network we would write out a new configuration file:

 auto br0
 iface br0
         bridge-ports glob swp1-47
         bridge-stp on
         setmcsnoop 0

 auto br1
 iface br1
         bridge-ports glob swp48-52
         bridge-stp on
         setmcsnoop 0

then bring the interfaces up with

 ifup -a

Note that ifup under Cumulus is different to standard Debian. It links to ifupdown2 which can inspect the current running state and apply only changes, rather than having to take an interface down and up on a standard server.

One deeply troubling thing about Cumulus Linux is it includes a minimal vi, but not a full implementation of vim.

But there are many other advantages that make up for this inexplicable oversight: being Debian-ish it has sudo, so you can give arbitrary permissions to multiple users rather than just show / enable / configure. You can easily update things with ssh. You can configure your switch with puppet. You can easily back up the entire configuration with rsync, version control it with etckeeper and bzr (sadly no git!). You can write code and run it directly on the switch which allows all kinds of options for monitoring and configuration.

We now have a few Cumulus Linux switches in production for private client networks. Here’s one providing lots and lots of bandwidth:

Even complex configurations can be handled relatively easily. For example, we have a customer with a private cloud who wants to run 20Gbps into each host, exposing different 10 different VLANs to their virtual servers, and then routing between them. This can be done on a 10G switch by bonding pairs of interfaces together, and then bridging the required VLANs on each of the bonded interfaces.

This config turns out to be nice and simple to write, and has the advantage of looking very similar on the switch and the server:

auto bond13            
iface bond13           
  bond-slaves swp1 swp2         
  bond-mode 802.3ad             
  bond-miimon 100               
  bond-use-carrier 1            
  bond-lacp-rate 1              
  bond-min-links 1              
  bond-xmit-hash-policy layer3+4
                       
auto bond14            
iface bond14           
  bond-slaves swp3 swp4         
  ....

auto br-tag130
iface br-tag130
  bridge-ports bond13.130 bond14.130 ...

auto br-tag2544
iface br-tag2544
  bridge-ports bond0.2544 bond1.2544  ...

BOGOF on .uk domains, cheap .beer and lots more

September 4th, 2015 by

Nominet are celebrating 30 years of .uk with a buy one, get one free offer on .uk domains. The offer applies to one and two year registrations of new .uk, .co.uk, .org.uk and .me.uk domains bought within a 7 day period.

If you’d like to take advantage of the offer, simply register the first domain through our website in the normal way, and then email us with the name of the second domain you’d like to register.

We’ve also got promotions available on lots of other domains. The discounts offered vary quite a lot by registry, particularly when it comes to multi-year bundles. Some of the best discounts are available for .beer, .host and .site.

Please see our Domains Page for the full list of current discounts.

Stormy weather, the clouds are growing.

August 26th, 2015 by

Photo-2015-08-26-12-31-10_1016

A customer of ours has been extending their private cloud. This adds another 160 cores, 160Gbps, 2TB of RAM and over half a petabyte of storage. On the left you can see the black mains cable, then the serial for out of bound configuration, then red cabling for 1Gbps each to our main network, then 20Gbps per server to the very secure private LAN on SFP+ direct attach.

The out of place yellow cable is network for the serial server above, and the out of place black one is serial to the 720Gbps switch which isn’t quite long enough to route neatly.

There’s a few more bits and pieces to add, but soon it will join their OpenStack cloud and substantially increase the rate at which their data gets crunched.

 

Snapshot Backups – Public Beta

August 21st, 2015 by

VPS snapshots
We’ve just launched a public beta test of a new service available on all of our virtual servers: snapshot backups.

Snapshot Backups make it trivial to set up backups of your virtual server. Simply select how many daily, weekly, and monthly backups you’d like to retain, and what time of day you want the backups taken, and we’ll do the rest.

Snapshot backup configuration

Snapshots work by taking an instantaneous image of your virtual server’s disk, which is then placed into our storage cloud.

The service is priced based on the size of your server’s disk, and the number of backups you choose to retain. You can alter your backup retention policy at any time.

During the public beta, the service is being charged at half price. If you want to try it out, simply click on the “Backups” section of your virtual server’s control panel. If you have any feedback, please do let us know.

Happy Incorporation Day to Us

August 14th, 2015 by

Happy Incorporation Day to Us
Happy Incorporation Day to Us
Happy Incorporation Day to Mythic Beasts
Happy Incorporation Day to Us

Fifteen years ago today someone with a boring job processed the paperwork and Mythic Beasts Ltd sprang into existence as a legal entity.

We had existed informally for a bit longer than that, we had registered the mythic-beasts.com that April, and our shell server, sphinx, had been running for a while, although it wouldn’t be until early 2001 that we sent our first invoice.

As we all work on t’internet, it’s difficult to all meet in the same pub this Friday for a celebratory drink. That will have to wait until our next full company meetup in September. Slamming the bedroom door, staying in and watching Brazil seems a more apt way for a teenage company to celebrate its bureaucratic anniversary.

Happy Tenth Eleventh Birthday to The Cloud

August 13th, 2015 by

We had a plan to post this last year, but we forgot.

On August 13th 2004, ten eleven years ago, our first ever invoice for a virtual dedicated server was paid.

Mythic Beasts Ltd.                https://www.mythic-beasts.com/
103 Beche Road
Cambridge
CB5 8HX

To:



────────────────────────────────────────────────────────────────
Invoice date                                        02-Jul‐2004
Invoice number                                                         
────────────────────────────────────────────────────────────────

────────────────────────────────────────────────────────────────
Ref         Date            Description                 Amount
────────────────────────────────────────────────────────────────
 xxxx     2004‐07‐02  VDS256 virtual dedicated         £400.00
                      server server-name 2004‐07‐02 to
                      2005‐07‐01
────────────────────────────────────────────────────────────────
                                      total            £400.00
────────────────────────────────────────────────────────────────

This VM ran until 2009 at which point it upgraded to a much faster dedicated server. It’s still operational today.

Over the intervening years, our basic service has evolved through three different virtualisation technologies and the virtual machines are now thirty two times the size that they started.

  • 256MB, User Mode Linux
  • 1024MB, User Mode Linux
  • 1024MB, Xen
  • 4GB, KVM
  • 8GB, KVM with SSD

As computers have become much larger and faster it’s increasingly hard to find a single application that can fill the capacity of a single machine, meanwhile service oriented architecture means that even simple applications are now built out of lots of lighty loaded servers, virtualisation is the magic that means that fifty applications built from tens of servers each can fit into a handful of physical servers. Whilst managing the hardware has become much simpler the number of instances to manage has exploded.

Increasingly these days not only are the servers virtual but the entire infrastructure, routers and all. We now have entirely virtual networks existing within our VM cloud using virtual routers to route traffic to virtual machines.

Five reasons why you should have your own domain for your email

July 24th, 2015 by

canstockphoto5518994

0. We sell domain names

OK, we lied, it’s six reasons, but the first probably isn’t very compelling so let’s get it out of the way first: buying domains gives us beer money.

Obviously we’ve got a commercial interest here, but Mythic Beasts exists because a bunch of students spotted that their university-provided email addresses would stop working once they graduated. We’ve now had the same personal email addresses for over 15 years.

1. Provider independence

This is the big one. Changing your email address is a massive pain. Not only do you need to tell all your human correspondents about your new address, but you need to tell just about every site that you’ve ever logged on to. Most sites use your email address to identify you, and that’s the only address that you can get a password reset sent to if you forget it.

Not so long ago, many people used the “free” addresses provided by their broadband (or dial-up) provider. This had the obvious problem that changing broadband providers meant changing your email address. Having your own domain puts you in control.

2. Real provider independence

Realising the problem of having your email address tied to your connectivity provider, many people have switched to using an address from a free email provider such as Gmail or Yahoo!, but this is really just moving the same problem elsewhere: your email address is now tied to your email provider.

What happens when you get fed up with the amount of advertising you’re exposed to in order to fund your “free” email account? Or your provider changes their email policy in a way that causes your address to be banned from mailing lists? Or you discover that the provider’s anti-spam policy is binning your legitimate email? Or they simply change their web interface in a way that you don’t like?

By using your own domain name, you retain choice of email provider.

3. Disposable addresses

It’s hard to do anything online without being asked to provide an email address, but how can you trust that your address isn’t going to be added to a spam list? If you have your own domain, you can have as many addresses as you want. You can even have “wildcard” addresses so that you can make up new addresses on the spot. For example, if my address is paul@example.com and I want to sign up to a service at www.somedodgysite.com, I could invent an address of:

paul-somedodgysite@example.com

If I start getting spam sent to that address then firstly, I know which site lost or sold my details and secondly, I can easily setup a rule to bin all mail to that address.

4. More interesting and memorable addresses

Unless you’re lucky enough to have a particularly uncommon name, any address you can get at the big free mail providers is likely to be some complex variant of your name. With your own domain name, you’ve got complete control. You could even have just a single letter such as p@example.com.

This also means that it’s less likely that your email will end up in someone else’s inbox by mistake. If one of your friends forgets that you’re joebloggs1937@gmail.com rather than just joebloggs@gmail.com, the email will get delivered to someone else. With your own domain, it’s far more likely that typo-ed addresses will get bounced, and the sender will notice the mistake.

5. Domains are cheap

EDIT 22/2/2020 – prices have gone up since this post was written, but domains are still cheap.

We sell UK domains for just £6+VAT £12+VAT for two years. £3.75 £7.20 is a year is a tiny price to pay for being in control of your own online identity. There’s also now a huge variety of generic top-level domains that can be had for not much more – .beer, .bike, .click, .cymru, .engineer, .guru, .scot, .wales, .wtf and hundreds more.

Of course, to use your domain, you’ll need somewhere to host it. We can sell you a hosting account too, but you don’t have to use us if you don’t want to. That’s the point!

OpenSSL release due

July 8th, 2015 by

If you read security lists, you will already be aware that we’re expecting a new release of OpenSSL tomorrow to fix a high severity vulnerability.

We will be reviewing the details as soon as the vulnerability is released, and will be patching the affected servers shortly after the updated packages are released, if necessary we will be contacting customer to reissue keys as we did after the now infamous Heartbleed vulnerability.

If you have any questions, or would like to upgrade to a manged service so we catch these kinds of issues for you, you can contact us at support@mythic-beasts.com.

Women in Technology and avoiding ISP filters

June 29th, 2015 by

One of the Mythic Beasts, Rhosyn has written an article on filtering for trefor.net, a widely read blog on technology and networking.

The part we particularly like this this quote,

As a long standing customer of Mythic Beasts 
(shameless plug; outstanding service and support, 
so good that I switched companies recently to work 
for them)

More disk space for all web hosting accounts

June 19th, 2015 by
512px-Floppy_disk_2009_G1

Sometimes disks get bigger and smaller at the same time

Disks just keep getting bigger. So, as the technology allows, we like to increase the disk space allocations of our hosting accounts too. We have just doubled the allocations of all our web hosting accounts. For the Super account, we’ve given it a 2.5x boost.

Account Was Now
Standard 1GB 2GB
Plus 5GB 10GB
Super 10GB 25GB
Jumbo 50GB 100GB

These are proper, full-fat GiB (230 bytes), not disk manufacturers’ GB (109 bytes).

All of our web hosting accounts can host as many domains as you want (free, provided the domains are registered with us), with as many email addresses, mailboxes, and web pages as you want. You are limited only by the total disk space. And if that’s not enough, it’s easy to upgrade from size of account to the next.

Order hosting accounts here

Finally, please don’t be misled by the picture above. We no longer use floppy disks for storage. Instead, all our web hosting servers now use mirrored “enterprise grade” SSDs for the best possible performance.