D-Link DIR-825/AC User Manual page 200

DIR-825/AC Wireless AC1200 Dual Band Gigabit Router with
3G/LTE Support and USB Port
User Manual
Parameter
Pre-shared key
Interface
NAT Traversal
Exchange mode
Enable DPD
Dead Peer Detection
delay
Dead Peer Detection
maximum fail
A key for mutual authentication of the parties.
Select a WAN connection through which the tunnel will pass. When
the <auto> value is selected, the router uses the connection set as the
default gateway.
The NAT Traversal function allows VPN traffic to pass through the
NAT-enabled router.
Select the Disabled value to disable the function.
Select the Enabled value to enable the function if it is supported by a
remote host.
Select the Force value to make the function be always on even if it is
not supported by a remote host.
Select the mode of negotiation from the drop-down list:
Main: The mode provides the most secure communication between
the parties in the course of negotiation of the authentication
procedures.
Base: The draft negotiation mode with preliminary authentication of
a host.
Aggressive: The mode provides faster operation as it skips several
stages of negotiation of the authentication procedures.
Select the checkbox to enable using DPD protocol for this tunnel.
Such a setting allows to check the status of a remote host: if encrypted
packets exchange between the router and the remote host breaks down,
the router starts sending DPD messages to the remote host. If the
checkbox is not selected, the Dead Peer Detection delay and
Dead Peer Detection maximum fail fields are not available for
editing.
A time period (in seconds) between attempts to check the status of a
remote host. By default, the value 5 is specified.
A number of DPD messages that were sent to check the status of a
remote host and left unanswered. By default, the value 3 is specified.
If a remote host does not answer the specified number of messages,
the router breaks down the tunnel connection, removes the encryption
keys, and tries to activate the connection.
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Configuring via Web-based Interface
Description