Netgear SRX5308 User Manual download pdf (Page 192)

Firewall Protection

192

ProSafe Gigabit Quad WAN SSL VPN Firewall SRX5308

4. Click the Set Interval button. Wait for the confirmation that the operation has succeeded

before you close the window.

Configure Port Triggering

Port triggering allows some applications running on a LAN network to be available to external

applications that would otherwise be partially blocked by the firewall. Using the port triggering

feature requires that you know the port numbers used by the application.

Note: Port triggering is supported for IPv4 devices only.

Once configured, port triggering operates as follows:

1. A computer make

s an outgoing connection using a port number that is defined in the

Port Triggering Rules table.

2. Th

e VPN firewall records this connection, opens the additional incoming port or ports that

are associated with the rule in the port triggering table, and associates them with the

computer.

3. The

remote system receives the computer’s request and responds using the incoming port

or ports that are associated with the rule in the port triggering table on the VPN firewall.

4. Th

e VPN firewall matches the response to the previous request and forwards the response

to the computer.

Without port triggering, the response from the external

application would be treated as a new

connection request rather than a response to a request from the LAN network. As such, it

would be handled in accordance with the inbound port forwarding rules, and most likely

would be blocked.

Note these restrictions on port triggering:

• On

ly one computer can use a port triggering application at any time.

• Af

ter a computer has finished using a port triggering application, there is a short time-out

period before the application can be used by another computer. This time-out period is

required so the VPN firewall can determine that the application has terminated.

Note: For additional ways of allowing inbound traffic, see Inbound Rules

(Port Forwarding) on page 135.

 To add a port triggering rule:

1. Select Secu

rity > Port Triggering. The Port Triggering screen displays. (The following

figure shows a rule in the Port Triggering Rules table as an example.)

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Netgear SRX5308 User Manual Page 192