The H.323 Alg - D-Link DFL-260E User Manual

6.2.9. The H.323 ALG

• Destination Port set to 5060 (the default SIP signalling port)
• Type set to TCP/UDP
3. Define four rules in the IP rule set:
• An Allow rule for outbound traffic from the clients on the internal network to the proxy
located on the DMZ interface.
• An Allow rule for outbound traffic from the proxy behind the DMZ interface to the remote
clients on the Internet.
• An Allow rule for inbound SIP traffic from the SIP proxy behind the DMZ interface to the
clients located on the local, protected network.
• An Allow rule for inbound SIP traffic from clients and proxies on the Internet to the proxy
behind the DMZ interface.
4. If Record-Route is not enabled at the proxy, direct exchange of SIP messages must also be
allowed between clients, bypassing the proxy. The following two additional rules are therefore
needed when Record-Route is disabled:
• An Allow rule for outbound traffic from the clients on the local network to the external
clients and proxies on the Internet.
• An Allow rule for inbound SIP traffic from the Internet to clients on the local network.
The IP rules with Record-Route enabled are:
OutboundToProxy
OutboundFromProxy
InboundFromProxy
InboundToProxy
With Record-Route disabled, the following IP rules must be added to those above:
OutboundBypassProxy
InboundBypassProxy
6.2.9. The H.323 ALG
H.323 is a standard approved by the International Telecommunication Union (ITU) to allow
compatibility in video conference transmissions over IP networks. It is used for real-time audio,
video and data communication over packet-based networks such as the Internet. It specifies the
components, protocols and procedures for providing such multimedia communication, including
Internet phone and voice-over-IP (VoIP).
H.323 Components
H.323 consists of four main components:
Terminals
Action Src Interface
Allow lan
Allow dmz
Allow dmz
Allow wan
Action Src Interface
Allow lan
Allow wan
Devices used for audio and optionally video or data
communication, such as phones, conferencing units, or
"software phones" such as the product "NetMeeting".
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Chapter 6. Security Mechanisms
Src Network Dest Interface
lannet dmz
ip_proxy lan
ip_proxy core
all-nets dmz
Src Network Dest Interface
lannet wan
all-nets lan
Dest Network
ip_proxy
lannet
dmz_ip
ip_proxy
Dest Network
all-nets
lannet