biotext.org.uk

Recently, one of our web servers fell victim to an apparent DoS attack, being hammered with hundreds of simultaneous dynamic page requests, far more than it’s specced to handle. To its credit, it stayed up, although it took about five minutes to log in via ssh, and when we spotted what was happening, the load average was over 100 which I think is the most loaded I’ve ever seen. The offending IP address was at UCSD who do a lot of bioinformatics, so there is a chance it was a misguided attempt to scrape a lot of data from us, rather than an actual hostile act, but in any case the upshot is the same.

It worried me that there was no easy way to remotely check the machine’s health, so I hacked together a quick PHP page to report various vital statistics on demand — load average, memory usage, disk usage etc. — and a Perl monitor that can raise the alarm if anything exceeds safe bounds.

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