Dubai: There are many filters that parents can install in their computers to prevent their children from accessing inappropriate websites - but the best ones cost money, an internet specialist has said.

Dr Fadi Aloul, Assistant Professor of Computer Engineering at the American University of Sharjah, said that while the standard proxy that most people have at home was reasonably effective, it was not foolproof.

"There are programmes you can install that are updated each day and have a better filtering system," he said. Typically, parents can buy filtering software for a fixed fee and then pay for updates.

Aloul said such updating was vital because otherwise the software becomes ineffective against new sites, just as anti-virus software loses its potency against the latest computer bugs if it is not updated regularly.

"Most people set their computers to update every 24 hours, but you can change that to every hour. It's done in the background so you don't notice it," Aloul said.

Proxy filter

"You wouldn't want to leave it a week [before updating] because these websites spread really fast as kids e-mail each other and talk about them in their chat sessions."

An additional benefit of parents installing filtering software, rather than relying on the proxy filter, was that online chat content could be monitored, Aloul said. Software is often designed to stop paedophiles from making contact with youngsters.

Typically, a filter might cost around $40 (Dh147) to install, with annual updates priced at around $12.

Many free filters are available on the internet, but these are less likely to be as up-to-date as paid-for systems, Aloul said.

He added: "The awareness of parents is not that good. I know very few parents who are aware of [filtering] programmes and install them."

Dubai-based company Butterfly Portal has developed software that, rather than blocking whole websites, just filters out the inappropriate content.

"In other [filtering] systems, the whole thing will be blocked if there is any bad content," said Hali Aboobacker from the company.