Australian water, energy, banking and telecommunications providers will be urged to strengthen their defences after a spate of online attacks designed to disrupt essential services.The Australian Signals Directorate issued advice for utility providers on Tuesday in a 16-page guide co-signed by Five Eyes intelligence partners in Canada, New Zealand, the UK and US.The advice follows sophisticated attacks on critical infrastructure by China-sponsored hacking groups, including one that compromised nine US telecommunications companies.It also comes weeks after Telstra suffered a national telecommunications outage that caused widespread disruption in retail stores, transport, and emergency services.The agency's paper, called CI Fortify, was developed…