Dell Inc. said it would buy tech-security company SonicWall Inc., the computer maker's latest effort to expand beyond its traditional hardware businesses.

The companies didn't disclose how much Dell agreed to pay, but people familiar with the matter valued the deal around $1.2 billion. One of these people said that the price tag included SonicWall's debt.

In 2010, private-equity firm Thoma Bravo LLC led a group that took SonicWall private in a deal valued at $717 million. The buyout firm Tuesday noted that SonicWall's value has significantly increased since that time.

SonicWall makes devices and associated software such as firewalls that protect corporate networks from cyberattacks. Dell said that it would sell SonicWall's tools to large and small businesses and that it would add the technology to some of its other products.

The acquisition of SonicWall is the latest in a string of purchases made by the Round Rock, Texas-based computer giant in its efforts to expand beyond its roots in personal computers and server systems. It is also the second deal made by the company's new software division. That group, led by John Swainson, the former chief executive of CA Inc., was formed last month.