Networking hardware vendor D-Link has added captcha protections to its line of home and small office routers in an effort to prevent automated attacks.

The system requires the user to enter a small amount of text displayed in an image, and is often used in online applications to prevent automated registration and fraud.

D-Link said that the new protections were being implemented in response to an increasingly sophisticated crop of malware.

The captcha system should thwart worms which automatically access networking equipment and slow performance, and prevent malware infections from hijacking networking equipment and redirecting traffic.

"We are excited to be the first in the market to implement captcha into our routers, providing yet another layer of security to our customers," said A J Wang, D-Link chief technology officer.

D-Link's move is one of several initiatives by security and networking vendors in recent months to prevent attacks.

Last summer, security researchers and vendors collaborated with software and networking hardware vendors to patch a major flaw in the DNS networking protocol.