Remember my success story of moving from MongoDB full text search index to ElasticSearch? After about one month of work our search service unexpectedly stopped. I received a bunch of emails from Logentries and NewRelic that server is no longer responsive.
Once I logged on to DigitalOcean account, I’ve seen message from administrators that server is sending a lot of traffic (UDP Flood), very likely compromised and therefore stopped. The link they give as instructions to fix the problem was quite comprehensive, but the most important info was in comments. A lot of people who were hit by problem had ElasticSearch deployed on their machines.