D-Link DFL-1660 User Manual page 460

9.4.6. IPsec Advanced Settings
Chapter 9. VPN
This specifies the total number of IP rules that can be connected to IPsec tunnels. By default, this is
initially approximately 4 times the licensed IPsecMaxTunnels and system memory for this is
allocated at startup. By reducing the number of rules, memory requirements can be reduced but
making this change is not recommended.
IPsec Max Rules will always be reset automatically to be approximately 4 times IPsec Max
Tunnels if the latter is changed. This linkage is broken once IPsec Max Rules is altered manually
so that subsequent changes to IPsec Max Tunnels will not cause an automatic change in IPsec Max
Rules.
Default: 4 times the license limit of IPsec Max Tunnels
IPsec Max Tunnels
Specifies the total number of IPsec tunnels allowed. This value is initially taken from the maximum
tunnels allowed by the license. The setting is used by NetDefendOS to allocate memory for IPsec. If
it is desirable to have less memory allocated for IPsec then this setting can be reduced. Increasing
the setting cannot override the license limit.
A warning log message is generated automatically when 90% of this setting's value is reached.
Default: The limit specified by the license
IKE Send Initial Contact
Determines whether or not IKE should send the "Initial Contact" notification message. This message
is sent to each remote endpoint when a connection is opened to it and there are no previous IPsec
SA using that gateway.
Default: Enabled
IKE Send CRLs
Dictates whether or not CRLs (Certificate Revocation Lists) should be sent as part of the IKE
exchange. Should typically be set to ENABLE except where the remote peer does not understand
CRL payloads.
Note that this setting requires a restart to take effect.
Default: Enabled
IPsec Before Rules
Pass IKE and IPsec (ESP/AH) traffic sent to NetDefendOS directly to the IPsec engine without
consulting the rule set.
Default: Enabled
IKE CRL Validity Time
A CRL contains a "next update" field that dictates the time and date when a new CRL will be
available for download from the CA. The time between CRL updates can be anything from a few
hours and upwards, depending on how the CA is configured. Most CA software allow the CA
administrator to issue new CRLs at any time, so even if the "next update" field says that a new CRL
is available in 12 hours, there may already be a new CRL for download.
This setting limits the time a CRL is considered valid. A new CRL is downloaded when
IKECRLVailityTime expires or when the "next update" time occurs. Whichever happens first.
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