Is it time for a VoIP firewall?

Some say enterprises may soon need a special firewall to thwart the malicious hackers, spoofers and other threats that can imperil VoIP and other SIP-related communications.

Spam commonly proliferates using STMP and HTTP protocols, which are critical to e-mail and the Internet, but it could soon become the nemesis of SIP as well.

Session Initiation Protocol (SIP) is a VoIP call-control and application protocol technology serving as the Internet Engineering Task Force's de facto standard for initiating a multimedia interactive user session.

Andrew Graydon, vice president of technology with Mississauga, Ontario-based BorderWare Technologies Inc., said traditional security measures -- such as authentication, authorization and IPsec -- are not designed to secure and manage SIP-based communications in real time.

But, Graydon said, new technologies like SIP firewalls are emerging to address the protocol's distinct security requirements. A SIP firewall is an appliance that manages and protects the traffic, flow and quality of VoIP and other SIP-related communications.

According to Graydon, the industry is working to secure voice communications at the transport layer with VPN-like encryption. But he said hackers will eventually learn how to attack Internet calls at the application layer.

BorderWare's recently released hardware and software SIP-based firewall, SIPassure, authenticates user connections and allows system administrators to set and enforce VoIP security policies to address application layer exploits.

More specifically, SIPassure's features include:

  • Protection with a range of controls, including unique session profiling that prevent spam and denial-of-service (DoS) attacks.
  • Antispam filters for securing, managing, monitoring and administering SIP-enabled communications.
  • Built-in audit and reporting capabilities designed to address critical security issues by providing visibility into all SIP-related communications, including SIP proxy, SIP registrar, spam, user access and capacity planning.

    While SIP-based firewalls aren't necessary today, Teney Takahashi, market analyst for The Radicati Group Inc. in Palo Alto, Calif., said companies will soon need a device like SIPassure to protect themselves from communication exploits.

    "It would be prudent for a company not to invest in something like this over the next couple of years," Takahashi said. "If they're going to protect their e-mail and their Web traffic, they should also protect their SIP traffic -- especially if they have VoIP or an instant messaging system they rely on for business communications."

    Takahashi said companies such as Cisco Systems Inc. may have security measures in place to prevent attacks on its SIP networks, but BorderWare was the first to market with its dedicated application for filtering out illegitimate SIP traffic.

    He said some vendors have products that filter out IM traffic or VoIP traffic, but no other offering filters SIP traffic at the application layer like BorderWare.

    "It definitely seems that SIP is the chosen protocol for real-time communication," Takahashi said. "As this trend progresses over the next few years, a SIP-specific firewall will become very valuable to companies."

    This story originally appeared on

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