D-Link DFL-260 Product Manual - Page 274

Solution B - Without NAT

Page 274 highlights

6.2.8. The SIP ALG Chapter 6. Security Mechanisms DMZ interface as the contact address. • 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 IP address of the NetDefend Firewall. This rule will have core (in other words, NetDefendOS itself) as the destination interface. The reason for this is because of the NAT rule above. When an incoming call is received, NetDefendOS automatically locates the local receiver, performs address translation and forwards SIP messages to the receiver. This is done based on the SIP ALG's internal state. • An Allow rule for inbound traffic from, for example the Internet, to the proxy behind the DMZ. 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 additional rules are therefore needed when Record-Route is disabled: • A NAT rule for outbound traffic from the clients on the internal network to the external clients and proxies on, for example, the Internet. The SIP ALG will take care of all address translation needed by the NAT rule. The translation will occur both at the IP level and the application level. • An Allow rule for inbound SIP traffic from, for example the Internet, to the IP address of the DMZ interface. The reason for this is because local clients will be NATed using the IP address of the DMZ interface when they register with the proxy located on the DMZ. This rule has core as the destination interface (in other words, NetDefendOS itself). When an incoming call is received, NetDefendOS uses the registration information of the local receiver to automatically locate this receiver, perform address translation and forward SIP messages to the receiver. This will be done based on the internal state of the SIP ALG. The IP rules needed with Record-Route enabled are: OutboundToProxy OutboundFromProxy InboundFromProxy InboundToProxy Action NAT Allow Allow Allow Src Interface lan dmz dmz wan Src Network lannet ip_proxy ip_proxy all-nets Dest Interface dmz wan core dmz Dest Network ip_proxy all-nets dmz_ip ip_proxy With Record-Route disabled, the following IP rules must be added to those above: OutboundBypassProxy InboundBypassProxy Action NAT Allow Src Interface lan wan Src Network lannet all-nets Dest Interface wan core Dest Network all-nets ipdmz Solution B - Without NAT The setup steps are as follows: 1. Define a single SIP ALG object using the options described above. 2. Define a Service object which is associated with the SIP ALG object. The service should have: 274

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DMZ interface as the contact address.
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
IP
address
of
the
NetDefend
Firewall.
This
rule
will
have
core
(in
other
words,
NetDefendOS itself) as the destination interface.
The reason for this is because of the
NAT
rule above. When an incoming call is received,
NetDefendOS automatically locates the local receiver, performs address translation and
forwards SIP messages to the receiver. This is done based on the SIP ALG's internal state.
An
Allow
rule for inbound traffic from, for example the Internet, to the proxy behind the
DMZ.
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 additional rules are therefore
needed when
Record-Route
is disabled:
A
NAT
rule for outbound traffic from the clients on the internal network to the external
clients and proxies on, for example, the Internet. The SIP ALG will take care of all address
translation needed by the
NAT
rule. The translation will occur both at the IP level and the
application level.
An
Allow
rule for inbound SIP traffic from, for example the Internet, to the IP address of
the DMZ interface. The reason for this is because local clients will be NATed using the IP
address of the DMZ interface when they register with the proxy located on the DMZ.
This rule has
core
as the destination interface (in other words, NetDefendOS itself). When
an incoming call is received, NetDefendOS uses the registration information of the local
receiver to automatically locate this receiver, perform address translation and forward SIP
messages to the receiver. This will be done based on the internal state of the SIP ALG.
The IP rules needed with
Record-Route
enabled are:
Action
Src Interface
Src Network
Dest Interface
Dest Network
OutboundToProxy
NAT
lan
lannet
dmz
ip_proxy
OutboundFromProxy
Allow
dmz
ip_proxy
wan
all-nets
InboundFromProxy
Allow
dmz
ip_proxy
core
dmz_ip
InboundToProxy
Allow
wan
all-nets
dmz
ip_proxy
With
Record-Route
disabled, the following IP rules must be added to those above:
Action
Src Interface
Src Network
Dest Interface
Dest Network
OutboundBypassProxy
NAT
lan
lannet
wan
all-nets
InboundBypassProxy
Allow
wan
all-nets
core
ipdmz
Solution B - Without NAT
The setup steps are as follows:
1.
Define a single SIP ALG object using the options described above.
2.
Define a
Service
object which is associated with the SIP ALG object. The service should have:
6.2.8. The SIP ALG
Chapter 6. Security Mechanisms
274