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FPCConnectionLimitPolicy

Internet Security and Acceleration Server 2004/2006 SDK

The FPCConnectionLimitPolicy object represents the connection limit policy for an ISA Server array. A connection limit policy includes the following connection limits.

  • Default connection limits that establish how many concurrent transport-layer protocol connections may be accepted from a single IP address that is not configured as a special IP address. These include connection limits for TCP connections, for UDP connections, and for ICMP and other raw IP connections.
  • Custom connection limits that establish how many concurrent transport-layer protocol connections may be accepted from a single special IP address. These include connection limits for TCP connections, for UDP connections, and for ICMP and other raw IP connections.
  • A connection limit that restricts the total number of UDP, ICMP, and other raw IP connections that may be created for a single server publishing or access rule during one second.

When the TCP connection limit for an IP address is reached, no additional TCP connections are allowed for the IP address.

The UDP connection limit applies to connection mappings, rather than to connections. When the UDP connection limit for an IP address is reached and an attempt is made to create an additional UDP connection from that IP address, the oldest UDP connection that was created from the applicable IP address is closed, and the new connection is established.

A special IP address typically specifies a Web server or a chained proxy server, which would require many more connections than most other IP addresses. IP addresses are configured as special IP addresses by including them in a computer set that is referenced by the SpecialComputerSets property.

When the limit that restricts the number of connections created for a single rule during the current second is reached, no new connections will be created for traffic that has no connection associated with it, the packets will be dropped, and ISA Server will generate an event that can trigger a Connection Limit for a Rule Exceeded alert. After the current second passes, the counter is reset, and new connections can be created during the next second until the limit is reached again.

An additional connection limit can be defined in the FPCWebListenerProperties object for each Web listener and each network from which outgoing Web requests can be sent. These connection limits are not included in the policy defined by the FPCConnectionLimitPolicy object.

ISA Server 2006 introduces a flood mitigation feature that uses connection limits to mitigate connection flooding so that ISA Server can continue to function, even under a flood attack. This is accomplished by identifying and blocking clients that generate excessive traffic. For a table that lists the flood mitigation settings on the Flood Mitigation page in ISA Server Management and the corresponding administration COM properties, see Flood Mitigation.

The FPCConnectionLimitPolicy object is accessed through the ConnectionLimitPolicy property of an FPCArrayPolicy object.

Click here to see the ISA Server object hierarchy.

Inheritance

This object inherits from the FPCPersist object, which contains methods and properties related to the persistent storage of an object's data. They include methods for exporting the object's data to and importing it from an XML document.

Methods

The FPCConnectionLimitPolicy object does not define any methods.

Properties

The FPCConnectionLimitPolicy object has the following properties.

Property Description
DefaultLimit Gets an FPCConnectionLimit object that specifies the connection limits for a single IP address that is not configured as a special IP address.
DenyLogPerSecondLimit Gets or sets the maximum number of denied packets that will be logged during one second. (This property is introduced in ISA Server 2006.)
Enabled Gets or sets a Boolean value that indicates whether the connection limit policy is enabled.
LoggedDeniedPerMinute Gets or sets the number of logged denied packets from a single IP address during one minute that will trigger an alert. (This property is introduced in ISA Server 2006.)
LogQuotaRejectedTraffic Gets or sets a Boolean value that indicates whether traffic that exceeds a connection limit is logged. (This property is introduced in ISA Server 2006.)
RulePerSecondLimit Gets or sets the maximum number of connections that can be created for a rule during one second.
SpecialComputerSets Gets an FPCRefs collection that contains references to the FPCComputerSet objects defining the computer sets to which the special connection limits apply.
SpecialLimit Gets an FPCConnectionLimit object that specifies the connection limits for special IP addresses.

Methods Inherited from FPCPersist

Name Description
CancelWaitForChanges Cancels the registration established by the WaitForChanges method (for use in C and C++ programming only).
CanImport Returns a Boolean value that indicates whether the object's properties can be imported from the specified XML document.
Export Recursively writes the stored values of all the properties of the object and its subobjects to the specified XML document.
ExportToFile Recursively writes the stored values of all the properties of the object and its subobjects to the specified XML file.
GetServiceRestartMask Retrieves a 32-bit bitmask of the FpcServices enumerated type that specifies which services need to be restarted for currently unsaved changes to take effect.
Import Recursively copies the values of all the properties of the object and of its subobjects from the specified XML document to persistent storage.
ImportFromFile Recursively copies the values of all the properties of the object and of its subobjects from the specified XML file to persistent storage.
LoadDocProperties Provides the XML document's properties so that you can know what information can be imported from the document.
Refresh Recursively reads the values of all the properties of the object and of its subobjects from persistent storage, overwriting any changes that have not been saved.
Save Recursively writes the current values of all the properties of the object and its subobjects to persistent storage.
WaitForChanges Registers to wait for an event indicating that the contents of the object have changed (for use in C and C++ programming only).

Properties Inherited from FPCPersist

Name Description
PersistentName Gets the persistent name of the object. The persistent name of an object is a name that is unique for the object at the respective level of the COM object hierarchy.
VendorParametersSets Gets an FPCVendorParametersSets collection that can hold sets of custom data for extending the object.

Interfaces for C++ Programming

This object implements the IFPCConnectionLimitPolicy and IFPCConnectionLimitPolicy2 interfaces.

Requirements

Client Requires Windows XP.
Server Requires Windows Server 2003. Requires Windows Server 2003 or Windows 2000 for ISA Server 2004 Standard Edition.
Version Requires Internet Security and Acceleration (ISA) Server 2006 or ISA Server 2004.
IDL

Declared in Msfpccom.idl.

See Also

COM Objects

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