Websites were shut down, public servants received threatening phone calls and pornography was plastered across Kevin Rudd's home page in a major cyber protest against government plans to filter the internet.

The government's Cyber Security Operations Centre discovered the attack was coming on February 5 but was unable to stop the parliament house website going offline and Prime Minister Rudd's site becoming home to "Operation Titstorm".

Internet protest group Anonymous, known for its regular attacks on Scientology websites, was behind the actions which were led by a so-called denial of service charge on www.aph.gov.au.

Just after 8am (AEDT) on Wednesday the parliament's website was hit by 7.5 million requests for communication per second, Parliamentary Services Secretary Alan Thompson told AAP.

"We had some advice in the lead-up to today there was going to be some cyber attack," Mr Thompson said.