SONICWALL SonicOS 7.1 VoIP User Guide

SONICWALL SonicOS 7.1 VoIP

About SonicOS

This guide is a part of the SonicOS collection of administrative guides that describe how to administer and monitor the SonicWall family of firewalls. SonicOS provides network administrators with the management interface, API (Application Program Interface), and Command Line Interface (CLI) for firewall configuration by setting objects to secure and protect the network services, manage traffic, and provide the desired level of network service. This guide focuses on how to monitor and administer the VoIP Administration Guide.

Topics

• Working with SonicOS
• SonicOS Workflow
• How to Use the SonicOS Administration Guides
• Guide Conventions

Working with SonicOS

SonicOS provides a web management interface for configuring, managing, and monitoring the features, policies, security services, connected devices, and threats to your network. SonicOS runs on top of SonicCore, SonicWall’s secure underlying operating system.
The SonicOS management interface facilitates:

• Setting up and configuring your firewall
• Configuring external devices like access points or switches
• Configuring networks and external system options that connect to your firewall
• Defining objects and policies for protection
• Monitoring the health and status of the security appliance, network, users, and connections
• Monitoring traffic, users, and threats
• Investigating events

SonicWall offers two different modes of operation in SonicOS; the modes differ mainly in the areas of policy, object configuration and diagnostics.

• Policy Mode provides a unified policy configuration workflow. It combines Layer 3 with Layer 7 policy enforcement for security policies and optimizes the workflow for other policy types. This unified policy workflow gathers many security settings into one place, which were previously configured on different pages of the management interface.
• Classic Mode is more consistent with earlier releases of SonicOS; you need to develop individual policies and actions for specific security services. The Classic Mode has a redesigned interface.

This table identifies which modes can be used on the different SonicWall firewalls:

that
NSsp 13700|  |  | deliver advanced threat protection and fast
 |  |  | speeds that large enterprises, data centres, and
 |  |  | service providers need.
NSsp 15700| no| yes| The NSsp 15700 is designed for large-distributed
 |  |  | enterprises, data centres, government agencies
 |  |  | and services providers. It provides advanced
 |  |  | threat protection like Real-Time Deep Memory
 |  |  | Inspection, multi-instance firewall configuration,
 |  |  | and unified policy creation and modification, with
 |  |  | scalability and availability.
NSv Series| yes| yes| The NSv series firewalls offer all the security
 |  |  | advantages of a physical firewall with the
 |  |  | operational and economic benefits of
 |  |  | virtualization. The NSv firewalls can operate in
 |  |  | either Policy Mode or Classic Mode. You can
 |  |  | switch between modes, but some configuration
 |  |  | information from extra interfaces is removed.

In addition to the management interface, SonicOS also has a full-featured API and a CLI to manage the firewalls.
For more information, refer to:

• SonicOS 7.1 API Reference Guide
• SonicOS Command Line Interface Reference Guide

SonicOS Workflow

• When working with SonicWall products, you can use the following workflow as a guide for setting up your security solution.

You begin your planning as you start making your purchasing decisions. Your sales partners can help you assess your network and make recommendations based on the kinds of security services you need. You can learn more about SonicWall products by reviewing product information and solutions. After selecting the solution, you can schedule your implementation.
After planning and scheduling your solution, you begin setting up the firewalls. The Getting Started Guides for your products can help you begin setting up the pieces to your solution. The Getting Started guides are designed to help you install the firewall to a minimal level of operation. Before performing any detailed configuration tasks described in the SonicOS Administration Guides, you should have your firewall set up and basic operation validated.
The configuration block of the workflow refers to the many tasks that combine to define how your firewall is integrated into your security solution and how it behaves when protecting your environment. Depending on the features of your security solution, this task can be quite complex. The System Administration Guides are broken into key command sets and features. Some documents may be used for all solutions, but others may be used use only if you integrated that feature into your solution. For example, High Availability or Wireless Access Points are not necessarily used by all customers. More information about a feature’s workflow is presented in the feature administration guide. Refer to the specific Administration Guide for a SonicOS feature for more information.
Configuration tends to be a one-time activity, although you might make minor adjustments after monitoring performance or after diagnosing an issue. The configuration activity can be broken down into the more detailed flow as the following figure shows. This also mirrors the key functions that are listed across the top of the management interface.

There is some flexibility in the order in which you do things, but this is the general workflow you would follow when configuring your firewall. Start by defining the settings on the firewall. Next, you set up the system and other devices that your firewall is connected to, and you can choose to implement High Availability when done. After your device, network, and system is configured, you should define the objects that you want to monitor. Then you use those objects to define the policies that protect your network. The final step to preparing your setup is to validate the user authentication.

How to Use the SonicOS Administration Guides
The SonicOS Administration Guide is a collection of guides that detail the features represented by each of the main menu items in the management interface. Within each guide, you can find topics covering commands in that menu group, along with procedures and in-depth information. The exceptions are the SonicOS 7.1 Monitor Guide and the SonicOS 7.1 Objects Guide which combine the topics for each of those functions into a single book. To help you understand how the books align with the features and commands, the following figure shows the books organized like the SonicWall management interface.

The SonicOS Administration Guides, along with related documentation, such as the getting started guides, are available on https://www.sonicwall.com/support/technical-documentation/.

Guide Conventions

These text conventions are used in this guide:

NOTE: A NOTE icon indicates supporting information.
IMPORTANT: An IMPORTANT icon indicates supporting information.
TIP: A TIP icon indicates helpful information.
CAUTION: A CAUTION icon indicates potential damage to hardware or loss of data if instructions are not followed.
WARNING: A WARNING icon indicates a potential for property damage, personal injury, or death.

VoIP
Voice over IP (VoIP) is an umbrella term for a set of technologies that allow voice traffic to be carried over Internet Protocol (IP) networks. VoIP transfers the voice streams of audio calls into data packets as opposed to traditional, analog circuit-switched voice communications used by the public switched telephone network (PSTN). VoIP is the major driving force behind the convergence of networking and telecommunications by combining voice telephony and data into a single integrated IP network system. VoIP is all about saving cost for companies through eliminating costly redundant infrastructures and telecommunication usage charges while also delivering enhanced management features and calling services features.

Topics

• VoIP Security
• VoIP Protocols
• SonicWall’s VoIP Capabilities
• Settings

VoIP Security
Companies implementing VoIP technologies to cut communication costs and extend corporate voice services to a distributed workforce face security risks associated with the convergence of voice and data networks. VoIP security and network integrity are an essential part of any VoIP deployment.
The same security threats that plague data networks today are inherited by VoIP but the addition of VoIP as an application on the network makes those threats even more dangerous. By adding VoIP components to your network, you are also adding new security requirements.
VoIP encompasses some complex standards that leave the door open for bugs and vulnerabilities within the software implementation. The same types of bugs and vulnerabilities that hamper every operating system and application available today also apply to VoIP equipment. Many of today’s VoIP call servers and gateway devices are built on vulnerable Windows and Linux operating systems.

Topics
Security Appliance Requirements for VoIP

Security Appliance Requirements for VoIP
VoIP is more complicated than standard TCP/UDP-based applications. Because of the complexities of VoIP signalling and protocols, as well as inconsistencies that are introduced when a Security Appliance modifies source address and source port information with Network Address Translation (NAT), it is difficult for VoIP to effectively traverse a standard Security Appliance. Here are a few of the reasons why.

• VoIP operates using two separate protocols – A signalling protocol (between the client and VoIP Server) and a media protocol (between the clients). Port/IP address pairs used by the media protocols (RTP/RTCP) for each session are negotiated dynamically by the signalling protocols. Firewalls need to dynamically track and maintain this information, securely opening selected ports for the sessions and closing them at the appropriate time.
• Multiple media ports are dynamically negotiated through the signalling session – negotiations of the media ports are contained in the payload of the signalling protocols (IP address and port information). Firewalls need to perform deep packet inspection on each packet to acquire the information and dynamically maintain the sessions, thus demanding extra Security Appliance processing.
• Source and destination IP addresses are embedded within the VoIP signalling packets – A Security Appliance supporting NAT translates IP addresses and ports at the IP header level for packets. Fully symmetric NAT Security Appliances adjust their NAT bindings frequently, and may arbitrarily close the pinholes that allow inbound packets to pass into the network they protect, eliminating the service provider’s ability to send inbound calls to the customer. To effectively support VoIP a NAT Security Appliance must perform deep packet inspection and transformation of embedded IP addresses and port information as the packets traverse the Security Appliance.
• Firewalls need to process the signalling protocol suites consisting of different message formats used by different VoIP systems – Just because two vendors use the same protocol suite does not necessarily mean they interoperate.

To overcome many of the hurdles introduced by the complexities of VoIP and NAT, vendors are offering Session Border Controllers (SBCs). An SBC sits on the Internet side of a Security Appliance and attempts to control the border of a VoIP network by terminating and re-originating all VoIP media and signalling traffic. In essence, SBCs act as a proxy for VoIP traffic for non- VoIP-enabled Security Appliances. SonicWall Security Appliances are VoIP- enabled Security Appliances that eliminate the need for an SBC on your network.
NOTE: VoIP is supported on all SonicWall appliances that can run SonicOS, as long as the VoIP application is RFC-compliant.

VoIP Protocols
VoIP technologies are built on two primary protocols: H.323 and SIP. These protocols can be applied either globally or per firewall rule.
Topics

• H.323
• SIP

H.323
H.323 is a standard developed by the International Telecommunications Union (ITU). It is a comprehensive suite of protocols for voice, video, and data communications between computers, terminals, network devices, and network services. H.323 is designed to enable users to make point-to-point multimedia phone calls over connectionless packet-switching networks such as private IP networks and the Internet. H.323 is widely supported by manufacturers of video conferencing equipment, VoIP equipment and Internet telephony software and devices.
H.323 uses a combination of TCP and UDP for signalling and ASN.1 for message encoding. H.323v1 was released in 1996 and H.323v5 was released in 2003. As the older standard, H.323 was embraced by many early VoIP players.
An H.323 network consists of four different types of entities:

• Terminals – Client endpoints for multimedia communications. An example would be an H. 323-enabled Internet phone or PC.
• Gatekeepers – Performs services for call setup and tear down, and registering H.323 terminals for communications. Includes:
• Address translation.
• Registration, admission control, and status (RAS).
• Internet Locator Service (ILS) also falls into this category (although it is not part of H.323). ILS uses
• LDAP (Lightweight Directory Access Protocol) rather than H.323 messages.
• Multipoint control units (MCUs) – Conference control and data distribution for multipoint communications between terminals.
• Gateways – Interoperation between H.323 networks and other communications services, such as the circuit-switched Packet Switched Telephone Network (PSTN).

SonicWall’s VoIP Capabilities
IMPORTANT: If the Wireless-Controller-Only mode has been selected for the Wireless LAN Controller, VOIP is disabled.
Topics

• VoIP Security
• VoIP Network
• VoIP Network Interoperability
• Supported Interfaces
• Supported VoIP Protocols
• BWM and QoS
• How SonicOS Handles VoIP Calls

VoIP Security

• Traffic legitimacy – Stateful inspection of every VoIP signalling and media packet traversing the Security Appliance ensures all traffic is legitimate. Packets that exploit implementation flaws, causing effects such as buffer overflows in the target device, are the weapons of choice for many attackers. SonicWall Security Appliances detect and discard malformed and invalid packets before they reach their intended target.
• Application-layer protection for VoIP protocols – Full protection from application-level VoIP exploits through SonicWall Intrusion Prevention Service (IPS). IPS integrates a configurable, high-performance scanning engine with a dynamically updated and provisioned database of attack and vulnerability signatures to protect networks against sophisticated Trojans and polymorphic threats. SonicWall extends its IPS signature database with a family of VoIP-specific signatures designed to prevent malicious traffic from reaching protected VoIP phones and servers.
• DoS and DDoS attack protection – Prevention of DoS and DDoS attacks, such as the SYN Flood, Ping of Death, and LAND (IP) attack, which are designed to disable a network or service.
• Validating packet sequence for VoIP signalling packets using TCP to disallow out-of-sequence and retransmitted packets beyond the window.
• Using randomized TCP sequence numbers (generated by a cryptographic random number generator during connection setup) and validating the flow of data within each TCP session to prevent replay and data insertion attacks.
• Ensures that attackers cannot overwhelm a server by attempting to open many TCP/IP connections (which are never fully established due to a spoofed source address) by using SYN Flood protection.
• Stateful monitoring – Stateful monitoring ensures that packets, even though appearing valid in themselves, are appropriate for the current state of their associated VoIP connection.
• Encrypted VoIP device support – SonicWall supports VoIP devices capable of using encryption to protect the media exchange within a VoIP conversation or secure VoIP devices that do not support encrypted media using IPsec VPNs to protect VoIP calls.
• Application-layer protection – SonicWall delivers full protection from application-level VoIP exploits through SonicWall Intrusion Prevention Service (IPS). SonicWall IPS is built on a configurable, high-performance Deep Packet Inspection engine that provides extended protection of key network services including VoIP, Windows services, and DNS. The extensible signature language used in SonicWall’s Deep Packet Inspection engine also provides a proactive defence against newly discovered application and protocol vulnerabilities. Signature granularity allows SonicWall IPS to detect and prevent attacks based on a global, attack group, or per-signature basis to provide maximum flexibility and control false positives.

VoIP Network

VoIP over Wireless LAN (WLAN) – SonicWall extends complete VoIP security to attached wireless networks with its Distributed Wireless Solution. All of the security features provided to VoIP devices attached to a wired network behind a SonicWall are also provided to VoIP devices using a wireless network.

NOTE: SonicWall’s Secure Wireless Solution includes the network enablers to extend secure VoIP communications over wireless networks.

• Bandwidth Management (BWM) and Quality-of-Service (QoS) – Bandwidth management (both ingress and egress) can be used to ensure that bandwidth remains available for time-sensitive VoIP traffic. BWM is integrated into SonicWall Quality of Service (QoS) features to provide predictability that is vital for certain types of applications.
• WAN Redundancy and Load Balancing – WAN redundancy and load balancing allow for an interface to act as a secondary WAN port. This secondary WAN port can be used in a simple active/passive setup, where traffic is only routed through it if the primary WAN port is down or unavailable. Load balancing can be performed by splitting the routing of traffic based on destination.
• High Availability – High availability is provided by SonicOS high availability, which ensures reliable, continuous connectivity in the event of a system failure.

VoIP Network Interoperability

• Plug-and-protect support for VoIP devices – With SonicOS, VoIP device adds, changes, and removals are handled automatically, ensuring that no VoIP device is left unprotected. Using advanced monitoring and tracking technology, a VoIP device is automatically protected as soon as it is plugged into the network behind a Security Appliance.
• Full syntax validation of all VoIP signalling packets – Received signalling packets are fully parsed within SonicOS to ensure they comply with the syntax defined within their associated standard. By performing syntax validation, the Security Appliance can ensure that malformed packets are not permitted to pass through and adversely affect their intended target.
• Support for dynamic setup and tracking of media streams – SonicOS tracks each VoIP call from the first signaling packet requesting a call setup, to the point where the call ends. Only based on the successful call progress are additional ports opened (for additional signalling and media exchange) between the calling and called party.
• Media ports that are negotiated as part of the call setup are dynamically assigned by the Security Appliance. Subsequent calls, even between the same parties, use different ports, thwarting an attacker who might be monitoring specific ports. Required media ports are only opened when the call is fully connected, and are shut down upon call termination. Traffic that tries to use the ports outside of the call is dropped, providing added protection to the VoIP devices behind the Security Appliance.
• Validation of headers for all media packets – SonicOS examines and monitors the headers within media packets to allow detection and discarding of out-of-sequence and retransmitted packets (beyond the window). Also, by ensuring that a valid header exists, invalid media packets are detected and discarded. By tracking the media streams as well as the signalling, SonicWall protects the entire VoIP session.
• Configurable inactivity timeouts for signalling and media – To ensure that dropped VoIP connections do not stay open indefinitely, SonicOS monitors the usage of signalling and media streams associated with a VoIP session. Streams that are idle for more than the configured timeout are shut down to prevent potential security holes.
• SonicOS allows the administrator to control incoming calls – By requiring that all incoming calls be authorized and authenticated by the H.323 Gatekeeper or SIP Proxy, SonicOS can block unauthorized and spam calls. This allows the administrator to be sure that the VoIP network is being used only for those calls authorized by the company.
• Comprehensive monitoring and reporting – For all supported VoIP protocols, SonicOS offers extensive monitoring and troubleshooting tools:
• Dynamic live reporting of active VoIP calls, indicating the caller and called parties, and bandwidth used.
• Audit logs of all VoIP calls, indicating caller and called parties, call duration, and total bandwidth used. Logging of abnormal packets seen (such as a bad response) with details of the parties involved and condition seen.
• Detailed Syslog reports and ViewPoint reports for VoIP signalling and media streams. SonicWall ViewPoint is a Web-based graphical reporting tool that provides detailed and comprehensive reports of your security and network activities based on Syslog data streams received from the
• Security Appliance. Reports can be generated about virtually any aspect of Security Appliance activity, including individual user or group usage patterns and events on specific Security Appliances or groups of Security Appliances, types and times of attacks, resource consumption and constraints.

Supported Interfaces
VoIP devices are supported on the following SonicOS zones:

• Trusted zones (LAN, VPN)
• Untrusted zones (WAN)
• Public zones (DMZ)
• Wireless zones (WLAN)

Supported VoIP Protocols
Topics

• H.323
• SIP
• SonicWall VoIP Vendor Interoperability
• CODECs
• VoIP Protocols on which SonicOS Does Not Perform Deep Packet Inspection

H.323
SonicOS provides the following support for H.323:

• VoIP devices running all versions of H.323 (currently 1 through 5) are supported
• Microsoft’s LDAP-based Internet Locator Service (ILS)
• Discovery of the Gatekeeper by LAN H.323 terminals using multicast
• Stateful monitoring and processing of Gatekeeper registration, admission, and status (RAS) messages
• Support for H.323 terminals that use encryption for the media streams
• DHCP Option 150. The DHCP Server can be configured to return the address of a VoIP-specific TFTP server to DHCP clients
• In addition to H.323 support, SonicOS supports VoIP devices using the following additional ITU standards:
• T.120 for application sharing, electronic white-boarding, file exchange, and chat
• H.239 to allow multiple channels for delivering audio, video and data
• H.281 for Far End Camera Control (FECC)

SIP
SonicOS provides the following support for SIP:

• Base SIP standard (both RFC 2543 and RFC 3261)
• SIP INFO method (RFC 2976)
• Reliability of provisional responses in SIP (RFC 3262)
• SIP-specific event notification (RFC 3265)
• SIP UPDATE method (RFC 3311)
• DHCP option for SIP servers (RFC 3361)
• SIP extension for instant messaging (RFC 3428)
• SIP REFER method (RFC 3515)
• Extension to SIP for symmetric response routing (RFC 3581)

SonicWall VoIP Vendor Interoperability
Partial list of devices with which SonicWall VoIP interoperates lists many devices from leading manufacturers with which SonicWall VoIP interoperates.

CODECs

• SonicOS supports media streams from any CODEC – Media streams carry audio and video signals that have been processed by a hardware/software CODEC (COder/DECoder) within the VoIP device.
• CODECs use coding and compression techniques to reduce the amount of data required to represent audio/video signals. Some examples of CODECs are:
• H.264, H.263, and H.261 for video
• MPEG4, G.711, G.722, G.723, G.728, G.729 for audio

VoIP Protocols on which SonicOS Does Not Perform Deep Packet Inspection
SonicWall Network Security Appliances do not currently support deep packet inspection for the following protocols; therefore, these protocols should only be used in non-NAT environments.

• Proprietary extensions to H.323 or SIP
• MGCP
• Megaco/H.248
• Cisco Skinny Client Control Protocol (SCCP)
• IP-QSIG
• Proprietary protocols (Mitel’s MiNET, 3Com NBX, etc.)

BWM and QoS
One of the greatest challenges for VoIP is ensuring high speech quality over an IP network. IP was designed primarily for asynchronous data traffic, which can tolerate delay. VoIP, however, is very sensitive to delay and packet loss. Managing access and prioritizing traffic are important requirements for ensuring high-quality, real-time VoIP communications.
SonicWall’s integrated Bandwidth Management (BWM) and Quality of Service (QoS) features provide the tools for managing the reliability and quality of your VoIP communications.

Topics
Quality of Service
QoS encompasses many methods intended to provide predictable network behaviour and performance.
Network predictability is vital to VoIP and other mission-critical applications. No amount of bandwidth can provide this sort of predictability, because any amount of bandwidth is ultimately used to its capacity at some point in a network. Only QoS, when configured and implemented correctly, can properly manage traffic, and guarantee the desired levels of network service.
SonicOS includes QoS features that add the ability to recognize, map, modify and generate the industry standard 802.1p and Differentiated Services Code Points (DSCP) Class of Service (CoS) designators.

How SonicOS Handles VoIP Calls
SonicOS provides an efficient and secure solution for all VoIP call scenarios. The following are examples of how SonicOS handles VoIP call flows:

• Incoming Calls
• Local Calls

Incoming Calls
Incoming Call Sequence of Events shows the sequence of events that occurs during an incoming call.
INCOMING CALL SEQUENCE OF EVENTS

The following describes the sequence of events shown in Incoming Call Sequence of Events:

1. Phone B registers with VoIP server – The Security Appliance builds a database of the accessible IP phones behind it by monitoring the outgoing VoIP registration requests. SonicOS translates between phone B’s private IP address and the Security Appliance’s public IP address used in registration messages. The VoIP server is unaware that phone B is behind a Security Appliance and has a private IP address—it associates phone B with the Security Appliance’s public IP address.
2. Phone A initiates a call to phone B – Phone A initiates a call to phone B using a phone number or alias. When sending this information to the VoIP server, it also provides details about the media types and formats it can support as well as the corresponding IP addresses and ports.
3. The VoIP Server validates the call request and sends the request to phone B – The VoIP server sends the call request to the Security Appliance’s public IP address. When it reaches the Security Appliance, SonicOS validates the source and content of the request. The Security Appliance then determines phone B’s private IP address.
4. Phone B rings and is answered – When phone B is answered, it returns information to the VoIP server for the media types and formats it supports as well as the corresponding IP addresses and ports. SonicOS translates this private IP information to use the Security Appliance’s public IP address for messages to the VoIP server.
5. VoIP server returns Phone B media IP information to Phone A – Phone A now has enough information to begin exchanging media with Phone B. Phone A does not know that Phone B is behind a Security Appliance, as it was given the public address of the Security Appliance by the VoIP Server.
6. Phone A and Phone B exchange audio/video/data through the VoIP server – Using the internal database, SonicOS ensures that media comes from only Phone A and is only using the specific media streams permitted by Phone B.

Local Calls

• Local VoIP Call Sequence of Events shows the sequence of events that occurs during a local VoIP call.
• LOCAL VOIP CALL SEQUENCE OF EVENTS

The following describes the sequence of events shown in Local VoIP Call Sequence of Events:

1. Phones A and B register with VoIP server – The Security Appliance builds a database of the accessible IP phones behind it by monitoring the outgoing VoIP registration requests. SonicOS translates between the phones’ private IP addresses and the Security Appliance’s public IP address. The VoIP server is unaware that the phones are behind a Security Appliance. It associates the same IP address for both phones, but different port numbers.
2. Phone A initiates a call to Phone B by sending a request to the VoIP server – Even though they are behind the same Security Appliance, phone A does not know Phone B’s IP address. Phone A initiates a call to phone B using a phone number or alias.
3. The VoIP Server validates the call request and sends the request to phone B – The VoIP server sends the call request to the Security Appliance’s public IP address. The Security Appliance then determines phone B’s private IP address.
4. Phone B rings and is answered – When phone B is answered, the Security Appliance translate its private IP information to use the Security Appliance’s public IP address for messages to the VoIP server.
5. VoIP Server returns phone B media IP information to phone A – Both the called and calling party information within the messages are translated by SonicOS back to the private addresses and ports for phone A and phone B.
6. Phone A and phone B directly exchange audio/video/data – The Security Appliance routes traffic directly between the two phones over the LAN. Directly connecting the two phones reduces the bandwidth requirements for transmitting data to the VoIP server and eliminates the need for the Security Appliance to perform address translation.

Settings
Configuring the settings for your SonicWall network security appliance for VoIP deployments builds on your basic network configuration in the SonicWall Management Interface. This section assumes your network security appliance is configured for your network environment.
NOTE: For general information about VoIP, refer to VoIP.
Topics:

• Configuring VoIP Settings
• Configuring VoIP Logging

Configuring VoIP Settings
IMPORTANT: If the Wireless-Controller-Only mode has been selected for Wireless LAN Controller, any attempt to enable SIP or H.323 options displays an error message in the lower right corner of the browser window.
Configure VoIP through NETWORK | VoIP > Settings. This page is divided into three sections:

• General Settings
• SIP Settings
• H.323 Settings

General Settings
Navigate to NETWORK | VOIP > Settings to display the General Settings page.

The option Enable Consistent NAT enhances standard NAT policy to provide greater compatibility with peer-to-peer applications that require a consistent IP address to connect to, such as VoIP. Consistent NAT uses an MD5 hashing method to consistently assign the same mapped public IP address and UDP Port pair to each internal private IP address and port pair.
For example, NAT could translate the private (LAN) IP address and port pairs, 192.116.168.10/50650 and 192.116.168.20/50655 into public (WAN) IP/port pairs, as shown in IP address and port pairs.

IP ADDRESS AND PORT PAIRS

Private IP/Port Translated Public IP/Port

With Consistent NAT enabled, all subsequent requests from either host 192.116.168.10 or 192.116.168.20 using the same ports illustrated in the IP address and port pairs result in using the same translated address and port pairs. Without Consistent NAT, the port and possibly the IP address change with every request.
NOTE: Enabling Consistent NAT causes a slight decrease in overall security, because of the increased predictability of the address and port pairs. Most UDP-based applications are compatible with traditional NAT. Therefore, do not enable Consistent NAT unless your network uses applications that require it.
IMPORTANT: For Consistent NAT to work properly, the minimum time interval between calls must be at least 200 msec.

Enabling Consistent NAT
To enable consistent NAT

1. Select the Enable Consistent NAT option. This option is not selected by default.
2. Click Accept.

SIP Settings
The SIP Settings are displayed under the Enable Consistent NAT option on the General Settings page.

You can enable the SIP transformations by selecting the Enable SIP Transformations options. For more information refer to Enabling SIP.
By default, SIP clients use their private IP address in the SIP (Session Initiation Protocol) Session Definition Protocol (SDP) messages that are sent to the SIP proxy. If your SIP proxy is located on the public (WAN) side of the firewall and the SIP clients are located on the private (LAN) side of the firewall, the SDP messages are not translated and the SIP proxy cannot reach the SIP clients.

Enabling SIP
To enable SIP:

1. Navigate to NETWORK | VOIP > Settings.

2. In the SIP Settings section, choose whether to enable SIP transformation globally or by firewall rule:

   • Use global control to enable SIP Transformations. This option is selected by default.
   • Use firewall Rule-based control to enable SIP Transformations. Be sure to configure a firewall rule to control SIP transformations as described in SonicOS Policies.

3. If you are not configuring SIP transformations, go to Step 12.

4. Enable SIP Transformations is not selected by default. Select this option to:

   • Transform SIP messages between LAN (trusted zone) and WAN/DMZ (untrusted zone).
     You need to check this setting when you want the Security Appliance to do the SIP transformation.
     If your SIP proxy is located on the public (WAN) side of the Security Appliance and SIP clients are on the LAN side, the SIP clients by default embed/use their private IP address in the SIP/Session Definition Protocol (SDP) messages that are sent to the SIP proxy; hence, these messages are not changed and the SIP proxy does not know how to get back to the client behind the Security Appliance.

   • Enable the Security Appliance to go through each SIP message and change the private IP address and assigned port.

   • Control and open up the RTP/RTCP ports that need to be opened for SIP session calls to happen.
     NAT translates Layer 3 addresses, but not Layer 7 SIP/SDP addresses, which is why you need to select Enable SIP Transformations to transform the SIP messages.
     TIP: In general, you should select Enable SIP Transformations unless there is another NAT traversal solution that requires this feature to be turned off. SIP Transformations works in bi-directional mode, meaning messages are transformed going from LAN to WAN and vice versa.
     When you select the Enable SIP Transformations option, the other options become available.

5. Select Enable SIP Transformation on TCP connections to perform SIP transformations on TCP-based SIP sessions.

6. Select a Service Object from Perform transformations for TCP/UDP port(s) in Service Object. The default is SIP.
   NOTE: Select the option SIP-Group from the drop-down to cover both the SIP TCP and the SIP UDP.

7. Selecting Permit non-SIP packets on the signalling port enables applications such as Apple iChat and MSN Messenger, which use the SIP signalling port for additional proprietary messages. This option is not selected by default.
   IMPORTANT: Enabling this checkbox might open your network to malicious attacks caused by malformed or invalid SIP traffic.

8. If the SIP Proxy Server is being used as a B2BUA, enable the Enable SIP Back-to-Back User Agent (B2BUA) support setting. This option is disabled by default and should be enabled only when the Security Appliance can see both legs of a voice call (for example, when a phone on the LAN calls another phone on the LAN).
   TIP: If there is no possibility of the firewall seeing both legs of voice calls (for example, when calls are only made to and received from phones on the WAN), the Enable SIP Back-to-Back User Agent (B2BUA) support setting should be disabled to avoid unnecessary CPU usage.

9. Use the SIP Signaling inactivity time out (seconds) and SIP Media inactivity time out (seconds) options to define the amount of time a call can be idle (no traffic exchanged) before the firewall blocks further traffic. A call goes idle when placed on hold. Specify the maximum idle time when:

   • There is no signalling (control) message being exchanged in SIP Signaling inactivity time out.
     The minimum time is 30 seconds, the maximum time is 1000000 seconds (~1.2 days) and the default is 3600 seconds (60 minutes).

   • No media (for example, audio or video) packets are being exchanged in the SIP Media inactivity time out. The minimum time is 30 seconds, the maximum time is 3600 seconds (1 hour), and the default time is 120 seconds (2 minutes).

10. Use the Additional SIP signalling port (UDP) for transformations setting to specify a non-standard
    UDP port to carry SIP signalling traffic. Normally, SIP signalling traffic is carried on UDP port 5060.
    However, several commercial VOIP services use different ports, such as 1560. When this setting is non-zero (0 is the default; the maximum value is 65535), the Security Appliance performs SIP transformation on these non-standard ports.
    TIP: Vonage’s VoIP service uses UDP port 5061.

11. To track SIP endpoint registration anomalies, select the Enable SIP endpoint registration anomaly tracking option. This option is not selected by default. When it is selected, these options become available:

    • Registration tracking interval (seconds) – Specify the interval between checking for anomalies.
    • The default is 300 seconds (5 minutes).
    • Failed registration threshold – Specify the number of failed registrations before checking for anomalies. The default is 5 failures.
    • Endpoint block interval (seconds) – The default is 3600 (60 minutes).

12. Either:

    • Click Accept.
    • Go to H.323 Settings.

H.323 Settings

Configuring H.323 Settings

To configure H.323 settings

1. Navigate to NETWORK | VoIP > Settings | H.323 Settings.

2. Choose whether to enable H.323 transformation globally or by firewall rule:

   • Use global control to enable H.323 Transformations. This option is selected by default.
   • Use firewall Rule-based control to enable H.323 Transformations. Be sure to configure a firewall rule to control H.323 transformations.

3. If you are not configuring H.323 transformations, go to Step 5.

4. Select Enable H.323 Transformation to allow stateful H.323 protocol-aware packet content inspection and modification by the firewall. This option is disabled by default. When the option is selected, the other H.323 options become active.
   The firewall performs any dynamic IP address and transport port mapping within the H.323 packets, which is necessary for communication between H.323 parties in trusted and untrusted networks/zones. Disable the Enable H.323 Transformation to bypass the H.323 specific processing performed by the firewall.

5. Select Only accept incoming calls from Gatekeeper to ensure all incoming calls go through the Gatekeeper for authentication. The Gatekeeper refuses calls that fail authentication.

6. In the H.323 Signaling/Media inactivity time out (seconds) field, specify the amount of time a call can be idle before the firewall blocks further traffic. A call goes idle when placed on hold. The default time is 300 seconds (5 minutes), the minimum time is 60 seconds (1 minute), and the maximum time is 122400 seconds (34 hours).

7. The Default WAN/DMZ Gatekeeper IP Address field has a default value of 0.0.0.0. Enter the default H.323 Gatekeeper IP address in this field to allow LAN-based H.323 devices to discover the Gatekeeper using the multicast address 225.0.1.41. If you do not enter an IP address, multicast discovery messages from LAN-based H.323 devices go through the configured multicast handling.

8. Click Accept.

Topics

• Configuring Bandwidth on the WAN Interface
• Configuring VoIP Access Rules

Configuring Bandwidth on the WAN Interface
NOTE: For information on Bandwidth Management (BWM) and configuring BWM on the WAN interface, see SonicOS POLICY Guide.

Configuring VoIP Access Rules
By default, stateful packet inspection on the firewall allows all communication from the LAN to the Internet and blocks all traffic to the LAN from the Internet. Additional network access rules can be defined to extend or override the default access rules.
If you are defining VoIP access for client to use a VoIP service provider from the WAN, you configure network access rules between source and destination interface or zones to enable clients behind the firewall to send and receive VoIP calls.

TIP: Although custom rules can be created that allow inbound IP traffic, the firewall does not disable protection from Denial of Service attacks, such as the SYN Flood and Ping of Death attacks.
NOTE: You must select Bandwidth Management on NETWORK | System > Interfaces for the WAN interface before you can configure bandwidth management for network access rules.

Configuring VoIP Logging
You can enable the logging of VoIP events, which are displayed on DEVICE | Log

Settings.

Call Status
The NETWORK | VoIP > Call Status page allows you to monitor all currently active VoIP calls. Use the Search feature to locate specific entries.

The VoIP Call Status table displays the following information about the active VoIP connection:

• Caller IP – the IP address of the device from which the call was initiated
• Caller-ID – the unique identifier for each initiated call
• Called IP – the IP address of the device on which the call was received
• Called-ID – the unique identifier for each received call
• Protocol – the type of protocol used by the call (SIP and SIP TCP/UDP calls, and H.323 calls).
• Data Transferred – the total amount of data transferred in MB.
• Time Started – the date and time that the call started.

You can see the caller and called information as well as how long the call has been in progress and the bandwidth used. Both active H.323 and SIP calls are shown on the VoIP Call Status page.
H.323 Transformations and SIP Transformations must be enabled on the NETWORK | VoIP > Settings page for the corresponding calls to be shown. Only when these options are enabled does SonicOS inspect the VoIP payload to track call progress.
To reset the connections for all the active calls in progress, click FLUSH ALL. This also removes all VoIP call entries from the table.

SonicWall Support

Technical support is available to customers who have purchased SonicWall products with a valid maintenance contract.
The Support Portal provides self-help tools you can use to solve problems quickly and independently, 24 hours a day, 365 days a year. To access the Support Portal, go to https://www.sonicwall.com/support.
The Support Portal enables you to:

• View knowledge base articles and technical documentation
• View and participate in the Community forum discussions at  https://community.sonicwall.com/technology-and-support.
• View video tutorials
• Access https://mysonicwall.com.
• Learn about SonicWall Professional Services
• Review SonicWall Support services and warranty information
• Register for training and certification
• Request technical support or customer service
• To contact SonicWall Support, visit https://www.sonicwall.com/support/contact-support.

About This Document

• SonicOS VoIP Administration Guide
• Updated – December 2023
• Software Version – 7.1
• 232-005872-00 Rev A

Copyright © 2023 SonicWall Inc. All rights reserved.
The information in this document is provided in connection with SonicWall and/or its affiliates’ products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of products. EXCEPT AS SET FORTH IN THE TERMS AND CONDITIONS AS SPECIFIED IN THE LICENSE AGREEMENT FOR THIS PRODUCT, SONICWALL AND/OR ITS AFFILIATES ASSUME NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL SONICWALL AND/OR ITS AFFILIATES BE LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF PROFITS, BUSINESS INTERRUPTION OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF SONICWALL AND/OR ITS AFFILIATES HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SonicWall and/or its affiliates make no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. and/or its affiliates do not make any commitment to update the information contained in this document. For more information, visit https://www.sonicwall.com/legal.

End User Product Agreement
To view the SonicWall End User Product Agreement, go to: https://www.sonicwall.com/legal/end-user-product-agreements/.

Open Source Code
SonicWall Inc. is able to provide a machine-readable copy of open source code with restrictive licenses such as GPL, LGPL, AGPL when applicable per license requirements. To obtain a complete machine-readable copy, send your written requests, along with certified check or money order in the amount of USD 25.00 payable to “SonicWall Inc.”, to:

• General Public License Source Code Request
• Attn: Jennifer Anderson
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References

• SonicWall Community | Technology and Support
• MySonicWall
• MySonicWall
• sonicwall.com/legal
• sonicwall.com/legal/end-user-product-agreements/
• sonicwall.com/support
• sonicwall.com/support/contact-support
• sonicwall.com/support/technical-documentation/
• sonicwall.com/support/technical-documentation/?language=English&category=Firewalls&resources=Administration%20Guide&version=7.1
• sonicwall.com/support/technical-documentation/?language=English&category=Firewalls&resources=Getting%20Started%20Guide
• sonicwall.com/support/technical-documentation/?q=sonicos%20api&language=English
• sonicwall.com/support/technical-documentation/sonicos-7-1-api
• sonicwall.com/support/technical-documentation/sonicos-7-1-monitor

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