ATLANTA, GA. — Tom Noonan, chief executive officer of Internet Security Systems, plans to use an “opening bell” ceremony at the Nasdaq to warn executives about continuing vulnerabilities to computers and networks.

Noonan will speak in New York on Tuesday morning.

“As a nation we must realize that the Internet is our country’s most porous border,” Noonan said in a statement. “However, security companies like ISS are working around the clock to preempt threats to our nation’s networks and key Internet-connected resources such as water and electricity. By gathering strategic intelligence, developing protection solutions and collaborating closely with government organizations, the security industry is playing a major role in defending the U.S. from potentially devastating attacks.”

Rather than decreasing since the 9-11 2001 terror attacks, the number of vulnerabilities has increased, Noonan said. In the first six months of 2006, the number of documented vulnerabilities reached nearly 4,000 as compared to 2,500 in all of 2001, he said.