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I have a VPS with Ubuntu. I host a small website (~10 visitors at the same time). Sometimes the website starts lagging. It lags so bad that my SSH connection starts lagging too. Running top
says that 2 instances of apache2
take up 50% CPU each.
I assume this is a DoS
attack. I've copy-paste installed a few iptables
scripts that made sense, but this has not helped.
I installed libapache2-mod-evasive
-- I'm sure it blocks the attacker, but I'm still lagging.
What can I do? Can I at least find the IP of the attacker?
I have strong experience with Linux, but almost zero experience with being a server admin.
Are you serving static files or dynamic content. The lag could be due to inefficient database queries when creating dynamic content. – Stacey Richards – 2011-09-15T13:53:00.547
@Stacey, content is PHP+MySQL. I agree that it could be from that, but I know for a fact that it's not. Not only do I log slow queries, but my database server is on another VPS. More importantly CPU is used up by
apache2
, notmysqld
– Mikhail – 2011-09-15T15:10:03.487Do the queries return large amounts of data that take a long time for PHP to process? Do you log script execution time in addition to query times? – Stacey Richards – 2011-09-15T15:14:31.520