The deal follows Citrix’s $323m acquisition in June of NetScaler Inc, which offers devices for data centers with a combination of features including load-balancing, caching, compression, SSL acceleration, and SSL VPN.

The Teros team will be added to Citrix’s application networking group to extend security features on NetScaler’s application delivery product line.

Sunnyvale, California-based Teros, which has raised a total of $34.5m in funding since its formation in 2000, said its web application firewalls are now protecting applications at many of the world’s largest financial institutions, corporations, and government agencies. It said its firewall devices work in conjunction with network firewalls and intrusion-prevention systems, and use technology that learns an application’s behavior, inspects incoming and outgoing traffic, and allows acceptable application behavior to be executed while blocking unacceptable behavior.

Citrix said that delivering secure web applications is particularly challenging because web vulnerabilities are easy to exploit, and attacks cannot be detected by traditional security products. However, because web applications provide direct access to some of the most sensitive data, including financial records, credit card numbers, and customer identity information, they are attractive targets for hackers.

Adding Teros technology to NetScaler will provide the industry’s broadest set of defenses against web and XML web services threats, said Citrix.