Running an Ethereum node on a VPS from Digital Ocean

When I saw an offer from Digital Ocean for $10 credit I thought I'd try and run an Ethereum node on their smallest $5 VPS instance ("droplet") for free for two months. (I had to pay $5 on registration so it wasn't completely free.) I tried to find information on how much CPU usage was acceptable (apart from not "excessive"), but couldn't.

It was pretty straightforward to do. I used an Ubuntu image with node.js. I picked Ubuntu by mistake, when I intended to use Debian, but I'm equally unfamiliar with the differences between all the distros, so it didn't make much difference.

I used the cpulimit utility to limit CPU use to 20% while it downloaded the blockchain. Even so the process died a few times, I'm not sure if that was because it was detected as using much CPU, or ran out of memory. I experimented with the limit - 10% seemed to be too low and it couldn't find peers, probably because it was too slow for the other nodes to talk to. After 30% usage for a few minutes it got killed off, but at 20% it downloaded the blockchain in a few hours. I added swap space part way through, in case that helped.

Once it caught up I limited it to 10% as even though it was only downloading a block every few seconds it still seemed to want to use a lot of CPU.

You can sign up for a VPS with $10 credit here: https://www.digitalocean.com/?refcode=6588d64bda60. To be completely transparent - if you sign up and then spend money with them I get up to $25 for each referral. Other VPS hosting companies are available.

(You'll want to set up a firewall and lock things down a bit, but I'm not going to cover that here.)

Cryptography and evil

I was going to write a blog post about mathematical cryptography problems, like good hash algorithms, getting padding right and other juicy problems and contrasting them to social cryptography problems, like trusting keys and blockchain forking. Then I came across this page on Ethereum problems:

While before cryptography was, by and large, a purely computational and information-theoretic science, with strong guarantees built on security assumptions that are close to absolute, once money enters the picture the perfect world of mathematics must interact with a much more messy reality of human social structures, economic incentives, partial guarantees and known vulnerabilities that can only be mitigated, and not outright removed.

That says it better than I could. However I would also have said one of the underlying problems is evil, such as manifested in a 51% attack (that's about one specific attack, but it applies to cryptocurrency generally). Lots of interesting problems to solve!

Ethereum - for when you get bored of bitcoin

A couple of years ago I started reading up about bitcoin, and I put some of what I'd found into Bitcoin - digging deeper.... Whilst what the effect that cryptocurrency will have on the world is interesting I'm finding the potential use of the blockchain (simply put - a distributed pretty much guaranteed trustworthy ledger) more interesting.

Recently I've come across ethereum, which is building its own blockchain for use with smart contracts, such as making sure musicians get paid when you stream their music. Now I find that really interesting.

Sometimes the PR side of such projects isn't too great, but that home page is really good at explaining what it's all about at a superficial level. There are lots of levels below that though.

More another day, including using technology to overcome evil.