U.S. patent application number 13/930927 was filed with the patent office on 2013-10-31 for automated operation and security system for virtual private networks.
The applicant listed for this patent is RPX CORPORATION. Invention is credited to MICHAEL L. GINIGER, WARREN S. HILTON.
Application Number | 20130290704 13/930927 |
Document ID | / |
Family ID | 32396534 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130290704 |
Kind Code |
A1 |
GINIGER; MICHAEL L. ; et
al. |
October 31, 2013 |
AUTOMATED OPERATION AND SECURITY SYSTEM FOR VIRTUAL PRIVATE
NETWORKS
Abstract
A node device provides secure communication services over a data
network, to multiple computers that are coupled through the node
device and multiple other node devices. The node device includes a
network communication interface for coupling the node device to the
data network, a data storage containing cryptographic information
including information that is unique to the node device, a
tunneling communication service coupled to the network interface
configured to maintaining an encrypted communication tunnel with
each of multiple other node devices using the cryptographic
information, a routing database for holding routing data and a
router coupled to the tunneling communication service and to the
routing database. The router can pass communication from one
communication tunnel to another. A centralized server can be used
to control the node devices in a centralized manner, thereby
reducing or eliminating on-site administration of node devices.
Inventors: |
GINIGER; MICHAEL L.;
(Groton, MA) ; HILTON; WARREN S.; (Groton,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RPX CORPORATION |
San Francisco |
CA |
US |
|
|
Family ID: |
32396534 |
Appl. No.: |
13/930927 |
Filed: |
June 28, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12206263 |
Sep 8, 2008 |
8520670 |
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13930927 |
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|
10835060 |
Apr 30, 2004 |
7440452 |
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12206263 |
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09359570 |
Jul 22, 1999 |
6751729 |
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10835060 |
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60094125 |
Jul 24, 1998 |
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Current U.S.
Class: |
713/156 |
Current CPC
Class: |
H04L 63/0823 20130101;
H04L 63/0272 20130101 |
Class at
Publication: |
713/156 |
International
Class: |
H04L 29/06 20060101
H04L029/06 |
Claims
1. A method of configuring and authenticating a node device, the
method comprising: at a manufacturing facility, generating a public
key and a private key in the node device; storing the private key
by the node device in a protected non-volatile storage; providing
the public key to the manufacturing facility, by the node device;
generating a public key certificate that includes the node device's
public key and is signed with a private key associated with the
manufacturing facility, by the manufacturing facility; providing
the public key certificate to the node device, by the manufacturing
facility; storing the certificate in nonvolatile storage, by the
node device; providing an authentication chain to the node device
for authenticating the certificates of other node devices, by the
manufacturing facility; storing the authentication chain in
nonvolatile storage, by the node device; deploying the node device;
the node device authenticating itself to other node devices and
servers by using said private key to sign messages and sending the
signed messages and the public key certificate to the other node
devices or servers, said other node device or server then
authenticating the public key certificate using a second
authentication chain of the other node devices or servers and
confirming the messages were signed using the private key
corresponding to the public key in the public key certificate; and
additional node devices and servers authenticating to the node
device by using private keys of the additional node devices and
servers to sign messages and sending signed messages and the public
key certificates to the node device, the node device then
authenticating the public key certificates using the authentication
chain of the node device and confirming that, for each additional
node device or server, the messages were signed using the private
key corresponding to the public key in the public key certificate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/206,263, filed Sep. 8, 2008, entitled
AUTOMATED OPERATION AND SECURITY SYSTEM FOR VIRTUAL PRIVATE
NETWORKS (Atty. Dkt. No. RPXC-31069), which is a continuation of
U.S. patent application Ser. No. 10/835,060, filed Apr. 30, 2004,
entitled AUTOMATED OPERATION AND SECURITY SYSTEM FOR VIRTUAL
PRIVATE NETWORKS, now U.S. Pat. No. 7,440,452, issued Oct. 21,
2008, which is a divisional of U.S. patent application Ser. No.
09/359,570, filed Jul. 22, 1999, entitled AUTOMATED OPERATION AND
SECURITY SYSTEM FOR VIRTUAL PRIVATE NETWORKS, how U.S. Pat. No.
6,751,729, issued Jun. 15, 2004, which claims benefit of U.S.
Provisional Application No. 60/094,125, filed Jul. 24, 2009,
entitled AUTOMATED OPERATION AND SECURITY SYSTEM FOR VIRTUAL
PRIVATE NETWORKS, now expired, the specifications of which are
incorporated herein in their entirety.
TECHNICAL FIELD
[0002] This invention relates to establishing and operating virtual
private data networks.
BACKGROUND
[0003] Virtual private networks (VPNs) leverage the flexibility and
cost advantages of the Internet by passing information over the
Internet, or other shared Internet Protocol (IP) network, in a
secure manner. VPNs enable enterprises to securely bridge
geographically separated computers or local networks over the
Internet as an alternative to using expensive, leased-line networks
and other remote-access solutions. Internet Service Providers
(ISPs), recognizing the benefits of VPNs, are beginning to offer
multi-tiered VPN services to their customers.
[0004] Businesses, recognizing the benefits of VPNs, employ VPNs to
support a wide variety of connectivity needs including remote
dial-up access for telecommuters and mobile users, private line
augmentation and replacement of existing leased-line and frame
relay networks, extranet networking for secure and controlled wide
area access to corporate information resources by their business
partners, and segmented intranet networking for secure partitioning
of internal traffic across both the wide area and the local
area.
[0005] An important impetus for the adoption of VPN technology by
businesses is the significant cost saving associated with the
replacement of expensive remote access servers and associated long
distance dial-up charges, the substitution of inexpensive and
ubiquitous Internet access for expensive leased lines and frame
relay access, and the introduction of a flexible, fast, secure, and
inexpensive mechanism for exchanging data with suppliers and
customers.
[0006] At the present time, a number of standards and proprietary
schemes exist for encrypting and authenticating data packets that
traverse public or private data networks. In December 1995, the
Internet Engineering Task Force (IETF) published five Requests for
Comments (RFCs) that define formats and methods for encrypting and
authenticating Internet Protocol (IP) packets. More recently, the
IETF has published a series of Internet Drafts that update the
formats and methods for encrypting and authenticating IP packets.
The IETF initiative is called Internet Protocol Security
(IPSec).
[0007] The IETF is currently in the process of defining a data link
layer security protocol that is known by the name Layer 2 Tunneling
Protocol (L2TP). L2TP encapsulates data link layer PPP frames and
transmits them across public data networks by prepending an IP
header to the encapsulated PPP frames.
[0008] Microsoft Corporation has implemented a proprietary data
link layer security protocol called Point to Point Tunneling
Protocol (PPTP) that encrypts data layer PPP frames and transmits
them across public data networks by prepending an IP header to the
encrypted PPP frames.
[0009] The IETF has also published a series of Internet Drafts
intended to address the standardization of a key management
protocol by which IPSec devices negotiate their security
associations and keying material. The original name for this key
management scheme was called ISAKMP/OAKLEY; the more current name
is the Internet Key Exchange (IKE).
SUMMARY
[0010] According to a first of numerous aspects of the invention,
in general, a node device provides secure communication services
over a data network, such as the Internet or another public or
private packet-switched network, to multiple computers that are
coupled through the node device and multiple other node devices.
The node device includes a network communication interface for
coupling the node device to the data network. For example, the
network communication interface is an Ethernet interface that is
coupled to a cable modem or a digital subscriber loop (DSL) modem
or a serial interface coupled to a telephone modem for
communicating with an Internet service provider. The node device
is, for example, an edge device located at a customer premises or
at an Internet POP, a network device located at an intermediate
point in the Internet, or can be implemented in software on a
computer at the customer premises. The node device includes a data
storage containing cryptographic information including information
that is private to the node device. The information that is private
to the node device can include a private key of a public/private
key pair known only to the node device, and can further include a
certificate, such as a X.509 format certificate, which includes a
public key of the public/private key pair. The node device also
includes a tunneling communication service coupled to the network
interface and is configured to maintain an encrypted communication
tunnel with each of the multiple other node devices using the
cryptographic information. For example, the encrypted communication
tunnels are implemented using the IPsec or PPTP protocols. The node
device further includes a routing database for holding routing data
and a router coupled to the tunneling communication service and to
the routing database. The router is configured to accept
communication from a first of the computers that includes an
address of a second of the computers, to select one of the other
node devices based on the address of the second computer and the
routing data, and to pass the communication through the encrypted
communication tunnel to the selected node device.
[0011] The node device can include one or more of the following
features:
[0012] The router accepts the communication from the first of the
computers from the tunneling communication service after that
communication is received by the tunneling communication service
through one of the encrypted tunnels to the other node device.
[0013] The node device further includes a management module
configured to communicate with a server over the data network, to
use the information in the data storage that is private to the node
device for authentication with the server, and to accept
cryptographic information from the server for storing in the data
storage for use by the tunneling communication service in
maintaining the encrypted tunnels.
[0014] The management module is configured to receive communication
policy information from the server, for example information that
the node device uses to limit or prioritize communication between
node devices.
[0015] The node device further includes a local communication
interface, such as an Ethernet interface, coupling the node device
to the first of the computers. The router accepts the communication
from the first of the computers through the local communication
interface.
[0016] The node device further includes a communication agent
coupled to the local communication interface configured to accept a
broadcast communication from the first of the computers. That
broadcast communication is addressed to a multiple of other
devices, for example being a message broadcast according to the
BOOTP or DCHP protocol, or another type of request for
configuration data from the first local computer. The communication
agent is configured to forward the communication over one or more
of the encrypted communication tunnels to the other node
devices.
[0017] The communication agent can select one or more of the
encrypted communication tunnels prior to forwarding the
communication. For example, a DCHP message can be forwarded over a
single tunnel to another node device to which a DCHP server is
locally coupled, thereby avoiding forwarding the broadcast
communication to other node devices to which DCHP servers are not
connected. Selecting the tunnels can be based on configuration data
provided by a management server.
[0018] The router is further configured to accept routing data over
the encrypted communication tunnel from the other node devices, for
example according to the RIPv2 or OSPF protocols, and to update the
routing database using the accepted routing data.
[0019] Each of the encrypted communication tunnels belong to one of
multiple sets of tunnels, or VPN "domains," and the router is
configured to prevent forwarding of communication received from a
tunnel in one domain to a tunnel in another domain.
[0020] In another aspect, in general, a node device provides secure
communication services over a data network to multiple computers
that are coupled through the node device and multiple other node
devices. The node device includes a data storage containing
cryptographic information including information that is private to
the node device, a routing database for holding routing data, and a
processor. The processor is programmed to implement a tunneling
communication service for maintaining an encrypted communication
tunnel with each of the plurality of other node devices using the
cryptographic information, and to implement a router configured to
accept communication from a first of the computers, the
communication including an address to a second of the computers,
the router being further configured to select one of the other node
devices based on the address of the second computer and the routing
data, and to pass the communication through the encrypted
communication tunnel to the selected node device.
[0021] In another aspect, in general, the invention is software
stored on a computer-readable medium for causing a programmable
device, such as a node device or a general purpose computer, to
provide secure communication services over a data network to
multiple devices, such as node devices and general purpose
computers that are coupled to the node device through the data
network. The software causes the programmable device to perform the
functions of maintaining an encrypted communication tunnel with
each of the plurality of other devices using the cryptographic
information and routing communication, including accepting
communication from a first of the multiple devices, the
communication including an address to a second of the devices, to
select one of the tunnels based on the address of the second device
and the routing data, and to pass the communication through the
selected encrypted communication tunnel to the other device.
[0022] In another aspect, in general, a communication system
provides secure communication services to multiple computers
coupled over a data network. The system includes multiple node
devices coupled to the data network, wherein each of the computers
is coupled to the data network through at least one of the node
devices. The system also includes a server computer coupled to the
data network. The server is used for configuring the node devices,
including for sending commands to the node devices to establish
secure communication tunnels with other node devices. Each node
device includes a network communication interface for coupling the
node device to the data network, a data storage containing
cryptographic information including information that is private to
the node device, a tunneling communication service coupled to the
network interface configured to maintaining an encrypted
communication tunnel with each of the plurality of other node
devices using the cryptographic information, a routing database for
holding routing data, and a router coupled to the tunneling
communication service and to the routing database. The router is
configured to accept communication from a first of the computers
that includes an address to a second of the computers, to select
one of the other node devices based on the address of the second
computer and the routing data, and to pass the communication
through the encrypted communication tunnel to the selected node
device.
[0023] In another aspect, in general, a method provides secure
communication services between multiple computers each coupled to a
data network through one of multiple node devices. The method
includes establishing secure communication tunnels over the data
network between multiple pairs of the node devices, including
accessing cryptographic information stored in the node devices and
encrypting data passing between the pairs of node devices using the
cryptographic information. The method also includes accepting
communication from a first computer coupled to a first node device
directed to a second computer coupled to a second node device,
selecting a next node device based on an identification of the
second local computer included in the accepted communication,
passing the communication over a first of the secure communication
tunnels to the next node device, and passing the communication from
the next node device to the second local computer.
[0024] The method can include one or more of the following
features:
[0025] The next node device can be different than the second node
device to which the second computer is coupled, that is, the path
to the second node device is indirect through the next node device.
Passing the communication from the next node device to the second
computer then includes passing the communication over a second of
the secure communication tunnels from the next node device to the
second node device.
[0026] The method further includes receiving routing data over the
secure communication tunnels, and selecting the next node includes
using the received routing data.
[0027] The method further includes accepting broadcasted
communication from the first computer, for example a request for
configuration data from the local computer, and forwarding the
broadcast communication over one or more of the secure
communication tunnels to other node devices.
[0028] Establishing the secure communication tunnels can include
establishing a secure communication session with a server over the
data network, including authenticating the node device by the
server, and then accepting a command over the secure communication
session from the server to establish a secure communication tunnel
with another of the node devices. After accepting the command from
the server, the method includes establishing a secure communication
tunnel with the other of the node devices.
[0029] The method can further include generating the cryptographic
information, including generating a public key and a private key
for the node in the node device, storing the private key in a
protected storage in the node device, and providing the generated
public key for the node device to the server. Authenticating the
node device by the server then includes encoding a message using
the stored private key at the node device, sending the encoded
message to the server, and decoding the message using the public
key for the node device that was provided to the server.
[0030] In another aspect, in general, a method for configures and
authenticates a node device. The method includes the following
steps: At a manufacturing facility, (a) generating a public key and
a private key in the node device, (b) providing the public key to
the manufacturing facility, and (c) storing the private key in a
protected non-volatile storage in the node device. The node device
is then deployed, including coupling the node device to a data
network at a remote site, such as at a customer premises. At the
remote site, the method then includes (d) accessing the stored
private key, and (e) processing a message, for example generating a
digital signature for the message, using the private key and
sending the processed message over the data network to a server
coupled to the data network. At the server, the method includes (f)
receiving the processed message from the deployed node device, and
(g) authenticating the node device including processing the
received message using the public key that was generated in the
device.
[0031] The method for configuring and authenticating a node device
can further include, at the manufacturing facility, (b1) creating
an authentication chain, including generating a certificate, for
instance a standard X.509 format certificate, signed with a private
key associated with the manufacturing facility and including the
public key provided by the node device to the manufacturing
facility. The authentication chain may also include a root public
key, a root certification, or a chain of certificates that are used
to authenticate the node device. The method then further includes
(b2) providing the authentication chain to the node device, and
(b3) storing the authentication chain in a non-volatile storage in
the node device. Then, at the remote site, the method can further
include (e1) sending the authentication chain to the server over
the data network.
[0032] The method for configuring and authenticating a node device
can further include, prior to sending the authentication chain to
the server, accepting an identification for the server and an
address on the data network of the server to which the
authentication chain is sent.
[0033] The method can also include receiving a certificate from the
server, and authenticating the server using the accepted
certificate and the accepted identification of the server.
[0034] The method can also include, at the manufacturing facility,
providing an identifier of the node device to the manufacturing
facility, wherein the generated certificate includes the
identifier. Authenticating the node device then includes accessing
said identifier provided in the certificate.
[0035] The method for configuring and authenticating a node device
can further include, at the server, (h) after authenticating the
node device, sending a response to the node device that includes a
challenge message, and, at the remote device, (i) receiving the
response that includes the challenge message, processing the
challenge message using the stored private key, and sending the
processed challenge message to the server, thereby allowing the
server to determine that the sender of the processed challenge
message has the private key of the node device.
[0036] The invention includes one or more of the following
advantages:
[0037] Automated installation, configuration, operation, and
management of VPNs requires little or no manual configuration or
on-site maintenance.
[0038] Dynamic connectivity of computers through a mesh topology
VPN network permits content packets to be easily and efficiently
re-routed through mesh-topology, depending on the application
requirements of the user's organization. VPN devices can
incorporate the necessary intelligence to optimize network
bandwidth by integrating dynamic routing with VPN technology.
VPN-based networks can also automatically adapt to changes in
network topology.
[0039] The communication system provides comprehensive security to
guarantee the safe transmission of mission-critical data over
public networks. In addition to the secure encryption and
authentication of content, the protocols and processes used to
manage node devices from a central server are also secure. The
control information exchanged between management server(s) and VPN
devices is securely authenticated, encrypted, and protected from
replay and other spoofing attacks.
[0040] The centralized management functionality results in
simplicity of VPN setup and maintenance. For example, all security
policy information, key parameters (such as type, strength,
rollover times) and connectivity information are maintained in a
central management system. This permits a network manager to handle
operations from a single control point and it relieves branch
offices and users from employing on-site technicians or
administrators.
[0041] Dynamic routing enables the creation of meshed VPN network
topologies. The optimum path is automatically selected based on
security policy, setup connections, and routing parameters to
optimize bandwidth, save time, and reduce operating costs. On a
larger scale, users can form communities of interest by creating
their own virtual networks within existing enterprise topologies
using private or public networks. Dynamic VPN switches can handle
thousands of simultaneous active users, and can interconnect with
hundreds of other dynamic VPN switches.
[0042] Using multiple sets of tunnels, or domains, between which
the routers in the node devices do not forward communication, the
different domains can form "communities of interest" within a
larger domain. For instance, different divisions in a corporation
may have different domains within a corporate network. Access to a
domain occurs at the first node device that accepts communication
from a computer that is authorized to communicate with that domain.
When communication is sent from node to node, the content of the
communication does not have to be reexamined at each node to
determine whether it should be forwarded to particular computers,
since that communication is already associated with a particular
domain based on the tunnel it arrived on. This avoids an expensive
step of filtering packets multiple times as they pass from source
to destination, thereby providing higher data rates as compared to
a distributed filtering approach.
[0043] Still other aspects, features, and attendant advantages of
the present invention will become apparent to those skilled in the
art from a reading of the following detailed description of
embodiments constructed in accordance therewith, taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 is a block diagram which illustrates a first
exemplary VPN in which edge devices couple a number of IP
subnetworks over the Internet;
[0045] FIG. 2 is a block diagram which shows a physical connection
of an edge device over a communication link to the Internet;
[0046] FIG. 3 is a logical block diagram of an edge device;
[0047] FIG. 4 is a logical block diagram of a device management
module;
[0048] FIGS. 5A-C relate to configuration of cryptographic
information;
[0049] FIG. 5A is a diagram which illustrates relationships between
certificates at an edge device, a management server, manufacturing
systems, and a root manufacturing authority;
[0050] FIG. 5B is a block diagram which illustrates storage and
processing modules of a root manufacturer system and an edge
device, which are used to configure the edge device;
[0051] FIG. 5C is a flowchart of a manufacture-time configuration
procedure;
[0052] FIGS. 6A-B are block diagrams of alternative embodiments of
an edge device;
[0053] FIG. 7 is a block diagram which illustrates a VPN which uses
a network device to route data over the Internet;
[0054] FIG. 8 is a block diagram which illustrates multiple
segregated VPNs supported using common edge and network devices,
and illustrates a centralized firewall server coupled to a VPN;
[0055] FIGS. 9A-B are block diagrams of alternative arrangements of
edge devices;
[0056] FIG. 9A is a block diagram in which a customer premises is
linked to the Internet through multiple edge devices; and
[0057] FIG. 9B is a block diagram in which an edge device is
located and an Internet POP.
DETAILED DESCRIPTION
[0058] Referring to the drawing figures, like reference numerals
designate identical or corresponding elements throughout the
several figures.
[0059] Referring to FIG. 1, a first exemplary virtual private
network (VPN), which is configured and operated according to a
first embodiment of the invention, couples three Internet Protocol
(IP) subnetworks 125 over Internet 100. A separate edge device 110
couples each of subnetworks 125 to Internet 100. Each edge device
110 maintains a secure communication tunnel 115 with generally one
or more other edge devices 110 over which the edge devices securely
transfer communication. In this first embodiment, tunnels 115 are
based on IPSec security associations between edge devices 110 and
allow traffic to pass between the edge devices as if that traffic
were passed over a private communication link joining the edge
device. Tunnels 115 together function as a virtual network in which
each link which is implemented using a tunnel makes use of IP layer
network services to deliver information across the Internet. Other
embodiments alternatively use tunneling approaches such as those
based on the PPTP or L2TP protocols. In the example shown in FIG.
1, each edge device 110 maintains a tunnel 115 with both other edge
devices 110 in a fully connected mesh arrangement.
[0060] When an edge device 110 receives communication destined for
a computer on subnetwork 125 that is directly coupled to it, for
example receiving the communication over one of tunnels 115
connected to it, it passes that communication over the subnetwork
to that destination computer.
[0061] When an edge device 125 receives communication that is
destined for a computer 120 that is on the virtual private network,
but that is on a subnetwork 125 coupled to another edge device 110,
it selects one of tunnels 115 that are coupled to it, and passes
the communication through the tunnel to its destination. Note that
such communication destined for another subnetwork may originate at
a computer 120 on subnetwork 125 that is coupled to the edge device
110. However, the communication may also be accepted through a
tunnel 115 and routed by edge device 110 out another of tunnels
115. In this example, if the tunnel 115 that connects two of the
edge devices 110 is blocked, for example due to network congestion
or some other problem, the two edge devices 110 remain connected by
routing packets via the third edge device 110.
[0062] In alternative embodiments, Internet 100 can be another
public or private packet-switched data network, which allows access
to users who are not authorized to access the VPN. In the case of
the Internet 100, a wide class of users has access to the
communication links which carry communication for the Internet, and
generally includes users who are not authorized to access the VPN.
In the case of a private packet-switched network, although the
general public may not have access to the network, there may
nevertheless be a subclass of users who are specially authorized to
access a partitioned VPN with the private network. Also, although
the description below is in terms of subnetworks 125 passing
Internet Protocol (IP) communication over the VPN, subnetworks
based on other protocols, such as IPX, can alternatively be coupled
by similarly functioning edge devices 110.
[0063] In this first embodiment, edge devices 110 use the Internet
Protocol Security (IPSec) protocol to implement the secure
communication tunnels 115 between one another. Alternative
tunneling protocols, such as PPTP and L2TP, are used in other
embodiments.
[0064] Each edge device 110 securely communicates with a management
server 130. Management server 130 is responsible for directing edge
devices 110 to establish tunnels 115 among one another, and
otherwise controlling their operation. This control includes
authenticating the edge devices, and providing information to the
edge devices that the edge devices use to establish particular
secure communication tunnels 115. For example, management server
130 provides session keys to the edge devices for use in encrypting
communication passing through particular tunnels. In this way,
management server 130 can limit which edge devices 110 can enter
into a VPN, and in particular, can prevent edge devices 110 that it
cannot authenticate from entering the VPN.
[0065] The approach to management of edge devices 110 is such that
as little as possible, if any, decentralized configuration of the
edge devices is necessary. For instance, each edge device 110 is
manufactured to include information necessary to establish a secure
and authenticated a communication link 135 with management server
130 when it initially starts up. Having established communication
link 135 with management server 130, an edge device 110 receives
additional configuration information directly from management
server 130.
[0066] Each edge device 110 maintains routing information in a
decentralized manner, for example by receiving routing information
over tunnels 115 from other edge devices 110. In the example shown
in FIG. 1, each edge device 115 has computers 120 coupled to it
that have addresses in a single logical subnet, that is, the
addresses of computers 120 coupled to the edge device are all in a
range of addresses defined by an IP subnetwork mask unique to that
edge device. An edge device 115 sends routing information to other
edge devices 115 that identifies the subnetwork so that the other
edge devices can determine whether to send packets addressed to
particular computers based on the address ranges handled by each
edge device. In this way, the edge devices do not necessarily have
to exchange routing information related to individual computers.
Each edge device 115 keeps track of which subnetworks are
accessible though each of tunnels 115 coupled to it, and routing
costs for sending communication to those subnetworks through each
of the tunnels.
[0067] Host addresses can optionally be assigned to computers by
the management server or by a DCHP server in such a way that an
edge device 110 (or a network device 820 described below with
reference to FIG. 8) can aggregate the addresses for multiple
computers or subnetworks for which the edge device provides access
to the VPN into a single subnetwork. In this way, it exchanges
routing information with other node devices indicating that it
provides a route to any computer in the aggregated subnetwork.
Routing information for small subnetworks or individual computers
does not have to be sent separately by the edge device to other
edge devices. Also, by aggregating the addresses into a subnetwork,
the routing information needed by other edge devices does not
changes often, only needing to be updated if the aggregated
subnetwork address (or aggregated subnetwork mask) changes.
[0068] Alternatively, or optionally for some computers, edge
devices 115 exchange host routing information. In one alternative,
a common address range is used for all the subnetworks, and routing
information that identifies which edge device 115 services each
computer 120 is exchanged.
[0069] In alternative embodiments, or optionally in conjunction
with decentralized exchange of routing information, routing
information can be assembled and distributed to edge devices 110 by
management server 130.
[0070] Referring to FIG. 2, edge device 110 and computers 120
coupled to it over its associated subnetwork 125 are located at a
customer premises 200. An Internet Point-of-Presence (POP) 220
provides an access point for communication between edge device 110
and Internet 100. In particular, customer premises 220 are coupled
to POP 220 by a communication link 216. In this first example,
communication link 216 is a dedicated communication link, such as a
T-1 or T-3 digital service leased from a telephone carrier. Edge
device 110 is connected to computers 120 over a local area network
link 208, such as an Ethernet link which forms part of subnetwork
125. A communication interface, such as a DSU/CSU, couples edge
device 110 to communication link 216. At POP 220, a corresponding
communication interface 222 is also coupled to communication link
216 and communication interface 222 is coupled to a router 226,
which provides a communication interface with Internet 110.
Communication links 212, 214, and 224, which pass communication
between edge device 110 and router 226 in general carry
communication for multiple tunnels 115, communication between edge
device 110 and management server 130, and other IP-based
communication to computers and other devices coupled to it over
Internet 100. That is, referring back to FIG. 1, individual tunnels
115 and communication links 135 are all carried over a common
physical communication link 216 (FIG. 2).
[0071] Referring to FIG. 9A, in alternative embodiments, computers
at a number of separate customer premises 200 can be coupled to
Internet 100 through an edge device 110. In FIG. 9A, a computer
120A is coupled over a private wide area network (WAN) 910 to a
second edge device 110A at another customer premises 200.
Optionally, WAN 910 may be coupled to Internet 100 through multiple
edge devices, for example both edge device 110 and edge device 110A
at another customer premises, thereby providing multiple redundant
routes from Internet 100 to computers 120 coupled to WAN 910.
[0072] Referring to FIG. 9B, edge device 110 is alternatively not
necessarily located at customer premises 200, but is rather at POP
220A. In this case, a private communication link 920, such as a
leased telephone line, couples customer premises 200 and edge
device 110 at POP 220, thereby maintaining the privacy of the VPN.
Multiple customer premises 200 can optionally be coupled to a
single edge device 110 in this manner.
[0073] In various alternative embodiments, different types of
communication links 216 are used. For instance, communication link
216 can be part of a broadband cable system such as a cable
television system, communication interface 214 is a cable modem and
communication interface 222 is a head-end cable interface that
communicates with multiple cable modems. Similarly, communication
link 216 can be part of a telephone network and communication
interface 214 is an Asynchronous Digital Subscriber Loop (ADSL)
modem. Alternatively, communication link 216 is a dial-up analog or
ISDN telephone connection, and communication interfaces 214 and 222
are modems.
[0074] Turning to FIG. 3, edge device 110 includes a number of
logical modules. A local interface module 310 provides a physical
and data-link layer (ISO layers 1 and 2) communication interface
with computers 120 (FIG. 2) coupled to the edge device through
local are network (LAN) link 208 over subnetwork 125 (FIG. 1).
Local interface module 310 accepts and provides IP packets over an
internal data path 312 and interfaces with LAN link 208, for
example, a 10 Base-T Ethernet connection. An external interface
module 320 accepts and provides IP packets over data paths from and
to a number of other modules in the edge device, and provides
physical and data-link layer interfaces to communication link 212,
for instance, using another 10 Base-T Ethernet connection, which
couples the edge device to communication interface 214 (FIG.
2).
[0075] Central to operation of edge device 110 is device management
module 330. Device management module 330 is coupled over a data
path 332 to external interface module 320, over which it connects
to Internet 100 through POP 220 (FIG. 2) and then establishes a
communication session with management server 130 (FIG. 1). Edge
device 110 includes a stored management server identification 337,
such as an Internet host name or IP address, which management
module 330 uses in establishing the communication session with the
management server. As is discussed fully below, device management
module 330 makes use of a cryptographic identification 335 to
authenticate management server 130 (FIG. 1), to provide the
information needed by management server 130 to authenticate it, and
to pass encrypted information back and forth with the management
server according to a secure communication protocol. Device
management module 330 securely communicates with management server
130 for purposes including obtaining a current version of the
device configuration, peer configuration, VPN security policy, peer
connectivity, and peer security association information.
[0076] Edge device 110 includes a router 360 and a tunneling
communication service 350, which are coupled between local
interface module 310 and external interface module 360. Tunneling
communication service 350, at the direction of device management
module 330, establishes and maintains communication with other edge
devices 110 to provide IPSec based communication between router 360
and corresponding router 360 in other edge devices 110.
[0077] Router 360 accepts IP packet from a number of data paths
within edge device 110 and routes those packets to selected others
of those data paths. In one instance, router 360 accepts IP packets
over data path 312 from local interface module 310. Based on
information stored in a routing database 315, the type of the
packet, and the destination address in the packet, router 360
determines whether the accepted packet should be routed over a data
path 364 through one of the tunnels maintained by tunneling
communication service 350, should be routed directly to the
Internet through external interface module 320 over data path 362,
or should be processed in some other way, for example if the packet
includes routing information.
[0078] In another instance, router 360 accepts IP packets from
tunneling communication service 350. Based on routing database 315,
router 360 determines whether an accepted packet is addressed to a
computer 120 on subnetwork 125 coupled to the edge device and
therefore should be passed over data path 312 to local interface
module 310, should be passed back to tunneling communication
service 350 to be forwarded over a tunnel to another edge device,
or should be processed in some other way.
[0079] Router 360 exchanges routing information with routers 360 at
other edge devices 110 over tunnels 115. In this embodiment the
exchange of routing information is according to a standard dynamic
routing protocol, such as the Routing Information Protocol version
2 (RIPv2) or the Open Shortest Path First (OSPF) Protocol. Router
360 uses this exchanged routing information to maintain routing
database 315. In this way, the basis for routing decisions made by
router 360 is dynamically updated, and router 360 can react to
changes in the configuration of remote networks behind edge devices
or the state of tunnels 115 (FIG. 1) coupling the edge devices. In
addition to or as an alternative to this type of dynamic routing,
device management module 330 can receive routing information from
management server 130 to update routing database 315.
[0080] Edge device 110 includes a relay agent 350, which forwards
certain classes of IP packets that are not specifically addressed
to other computers. In one relay mode, relay agent 350 accepts
BOOTP IP packets, which are broadcast by computers 120 over local
subnetwork 125 to obtain startup configuration data and received by
local interface module 310, and sends IP packets containing the
information in the accepted broadcast packets to the relay agents
in other edge devices or to a particular computer that can service
the request in the broadcast packet. In this way, in the case of
the BOOTP packets, a computer 120 can obtain configuration
information, such as its IP address and host name, from a BOOTP
server that is on the VPN but located on a different subnetwork,
even though such a packet would not normally have been routed to
that other network by router 360.
[0081] Referring to FIG. 4, device management module 330 includes
several logical components.
[0082] A key exchange module 410 is used to exchange cryptographic
keys with other computers or devices on Internet 100 in order to
establish secure tunnels with those computers or devices.
[0083] The DHCP client 420 implements the dynamic host
configuration protocol (DCHP), which is a standard protocol for the
dynamic and automatic assignment of Internet Protocol (IP)
addresses to end systems, such as personal computers, etc. which
are connected to IP-based network. In this embodiment, device
management module 330 uses DCHP client 420 to obtain an external IP
address for edge device 110. This address is associated with
external interface module 320, and is used by other devices on the
Internet to address IP packets, such as packets that encapsulate
traffic in tunnels 115, to the edge device.
[0084] The SNMP agent 440 implements the Standard Network
Management Protocol (SNMP). SNMP agent 440 provides monitored
information to other network management computers. The requests for
monitored information may come over one of the established tunnels,
over a designated secure network management tunnel, of from the
local subnetwork.
[0085] A scheduler 450 coordinates execution of processes and task
of the various modules of the edge device to ensure real-time
operation. Scheduler 450 is implemented as a state machine, and is
responsible, for example, for initiating rollover of session keys
and triggering protocol timeouts.
[0086] A trusted management protocol module 4S0 is used to accept
data from management server 130, which it then stores in device
database 325. Trusted management protocol 450 insures the integrity
of this data as it is transmitted between an edge device 110 and
management server 325. Data transferred using this protocol is
first encrypted with a unique symmetric key, which is itself then
encrypted with a public key corresponding to a private key held by
the recipient. This whole message is signed using the private key
of the sender. An anti-replay mechanism is also incorporated into
the protocol. This mechanism includes repeatedly exchanging
challenges and corresponding responses between the edge device and
the management server.
[0087] In use, an edge device 110 goes through several stages
including manufacture-time configuration, initial configuration and
startup at a customer premises, restarting at a customer premises
after a period of disconnection from the Internet, and normal
operation while connected to the Internet.
[0088] During the manufacturing stage, information is stored in
edge device 110 to allow it to be configured as automatically as
possible when initially started up at a customer premises. An
important aspect of the manufacturing stage is to store
cryptographic identification 335 (FIG. 3) in edge device 110.
[0089] Before use, typically after the manufacturing stage, a
management server identification 337 (FIG. 3), for instance, a
network address for accessing the server or a unique identifier
used in cryptographic certificates for the server, is provided to
the edge device.
[0090] FIG. 5A-C relate to configuration of cryptographic
information in edge devices 110. FIG. 5A shows an interrelationship
of certificates in a deployed system. FIG. 5B illustrates the
interaction of a manufacturing system 504 and an edge device 110
during manufacture-time configuration, and FIG. 5C is a flowchart
of that configuration.
[0091] Referring to FIG. 5A, each edge device 110, as well as
management server 130 include certificates that are used to
mutually authenticate one another. The certificates are arranged in
two separate chains. A root manufacturing certificate authority 502
has two pairs of public/private keys, in this embodiment 1024 bit
RSA keys. Two root manufacturing certificates 512 include these
public keys, and are optionally signed by another global
certificate authority. In this embodiment, certificates 512
conforms to the X.509v3 standard.
[0092] Configuration of edge devices 110 and management server 130
is carried out by a number of manufacture systems 504. Each
manufacturing system 504 has two pairs of public/private keys, and
has corresponding manufacturer certificates 514, each of which
includes one of the manufacturer public keys and is signed using a
different one of the root manufacture private keys. A particular
manufacture system 504 can periodically generate a new pair of
public/private keys and create new manufacturer certificates 514
signed by the root manufacture certificate authority.
[0093] Each edge device 110, as well as optionally management
server 130, has copies of root manufacturer certificates 512, or at
least the public keys of the root manufacturing certificate
authority, as well as a copy of manufacturer certificates 514 of
the manufacture system 504 used to configure its identity. Finally
each edge device has a pair of public/private key pairs, and two
corresponding device certificates which include a device public key
and which are signed with the corresponding manufacturer private
keys of the manufacture system 504 use to configure the device.
[0094] Referring now to FIGS. 5B-C, in operation, an edge device
110 exchanges one of the device certificates 516, and the
corresponding one of its two manufacturer certificates 514 with
management server 130. Using the root manufacturer public key in
the corresponding one of the two root manufacturer certificates
512, management server 130 first validates the signature of the
manufacturer certificate 514 it received from the edge device, and
then uses the manufacturer public key in that manufacturer
certificate to validate the device certificate 516 it received from
the edge device. In this way, management server 130 knows that it
holds a valid device public key for the edge device. Using a
corresponding sequence, edge device 110 validates a management
server public key for the management server. In this way, the edge
device and the management server mutually authenticate one another,
and then they use their peer devices' public keys to securely
exchange information. The two chains of certificates 512, 514, and
516 are redundant in that if one of the public keys of the root
manufacture private keys is compromised, the certificates in that
chain can be retired and no longer used, or optionally, the
certificates in the remaining chain can be used to securely
distribute a new set of certificates.
[0095] Referring still to FIGS. 5B-C, each edge device 110 is
configured at manufacturing time through an interaction with a
manufacture system 504. In the following description, the
referenced steps are illustrated in the flowchart shown in FIG. 5C
while the processing and data modules are shown in FIG. 5B. First,
root manufacturer system 504 generates a random seed 542 using a
random number generator 544 (step 580). Manufacturer system 504
transfers this random seed to edge device 110 (step 582).
Alternatively, edge device 110 internally generates random seed 542
(step 581), thereby reducing the possibility of compromising the
device private key. Edge device 110 then generates device public
key 522 and corresponding device private key 521 using a key
generation module 546 (step 584). In this embodiment, key
generation module 546 creates a 1024 bit public/private RSA key
pair. Edge device 110 then passes device public key 522 back to
manufacture system 504 (step 586), but retains device private key
521 within the edge device. Device private key 522 is preferably
never disclosed outside edge device 110, thereby assuring that the
edge device is the only device that can decrypt information
encrypted with device public key 522, and ensuring that data signed
with device private key 521 can be trusted by other devices to have
originated at that edge device 110. Manufacturer system 504 then
generates two device certificates 516 using a certificate module
540. Certificate module 540 creates each device certificate 516
such that it contains device public key 522 and is signed using the
corresponding manufacture private key 524 (step 588). In this way,
a device that receives a device certificate 516 and the
corresponding manufacturer certificate 514 and that has a trusted
copy root manufacture certificate 512 (or equivalently a copy of
the root public key) can validate device public key 522 and trust
the authenticity of that device public key. In this embodiment,
certificates 512, 514, and 516 all conform to the X.509v3 standard.
Manufacturer system 504 then transfers device certificates 516, its
own manufacturer certificates 514, and root manufacture
certificates 512 (or at least the root manufacturer public keys to
edge device 110 (step 590). Edge device 110 then stores the entire
cryptographic identification 335, which includes device public and
private keys 521, 522, root manufacture certificates 512,
manufacturer certificates 514, and device certificates 516, in
non-volatile memory.
[0096] In other related embodiments, edge device 110 keeps secret
its device private key 521. In one alternative, rather than storing
a copy of certificates 512, 514, and 516, the certificates are
stored elsewhere, such as in a central database. Since device
certificates 516 can be validated by a holder of certificates 514
and 512 a recipient of the device certificate can determine the
authenticity of the device public key in the certificate using a
trusted copy of root public key 520.
[0097] In other alternative embodiments, other approaches to
chaining certificates are used. For example, all certificates can
be signed by a common certificate authority, or different length
chains of certificates can be used.
[0098] After edge device 110 is delivered to a customer premises,
and initial configuration and startup is carried out. In a fully
automated startup mode, edge device 110 is connected to
communication device 214 (FIG. 2) and communication device 214 is
connected to a communication link 216 to an Internet POP 220. Edge
device 110 is also connected to local subnetwork 125. At the
initial startup, edge device 110, using DCHP client 420 in
management module 330, obtains an external IP address for
communicating with other devices on the Internet from a DCHP server
at POP 220. The local IP address on subnetwork 125 of edge device
110 is either determined by a configuration at the customer
premises, or is determined from management server 130.
[0099] A variety of alternative startup scenarios are also
supported by edge device 110. For instance, local and external IP
addresses may be statically assigned to edge device 110 and
manually entered before the initial startup.
[0100] Once edge device 110 has obtained an external IP address and
can communicate with other devices on the Internet, it attempts to
establish secure and authenticated communication with management
server 130 using trusted management protocol 430. This process
includes transferring a certificate chain, which includes one of
certificates 516 and a corresponding one of manufacturer
certificates 514, from edge device 110 to management server 130.
Since management server 130 has a copy of root manufacture
certificate 512, or equivalently a copy of the root public key, it
can authenticate certificate 516, thereby obtaining an
authenticated device public key 522 in the certificate. It then
authenticates edge device 110 using device public key 522 and a
signature with device private key 521 of a message sent from edge
device 110. Edge device 110 holds a trusted copy of root
manufacturer certificate 512, or equivalently a trusted copy of the
root public key, which it received at the time of manufacture, and
can authenticate management server 130 using the root manufacturer
public key using the same procedure used by management server 130
to authenticate edge device 110.
[0101] In alternative embodiments, further authentication of a user
is required before edge device 110 is allowed to enter the VPN. For
example a user at edge device 110 may be required to provide a
username and password. This username and password are authenticated
by management server 130, possibly using the services of an
authentication server, such as a RADIUS server, which centrally
holds authentication data for the organization managing the
VPN.
[0102] Once edge device 110 is in communication with management
server 130, it receives additional configuration information, such
as information related to routing and security policies from the
management server.
[0103] When management server 130 detects the presence of an edge
device 110, it determines to which other edge devices 110 it should
establish tunnels 115. For instance, management server 130 includes
a central database containing information about the VPN, such as
which edge devices 110 should be directly coupled by tunnels 115
and which edge devices 110 should route data from one tunnel 115 to
another.
[0104] In order to have a tunnel 115 established between two edge
devices 110, management server sends commands to each of the edge
devices 110 instructing them to add the tunnel. Management server
130 generates session keys that it securely transfers to the edge
devices for use to encrypt and decrypt data passing through the
tunnel joining the edge devices.
[0105] Alternatively, management server 130 can let the edge
devices determine the session keys themselves using standard key
exchange approaches, while still providing data, such as device
public keys, which the edge devices use to authenticate each other.
In one alternative embodiment, management server 130 instructs an
edge device 110 to establish a tunnel with another device that is
not managed by management server 130. In this case, edge device 110
and the other device authenticate one another using a protocol such
as IKE, and may rely on certificates signed by a common certificate
authority.
[0106] Once the edge devices have been commanded to create a
tunnel, and have generated or received from the management server
the needed cryptographic keys, the edge devices complete creation
of the tunnel joining them, and are able to securely pass data
between them. The edge devices update their routing databases, for
example by passing routing information over the newly created
tunnel, or by receiving routing data from the management
server.
[0107] When an edge device is removed from the VPN, the management
server commands its peer edge devices to shut down the tunnels
linked to it.
[0108] Optionally, when an edge device 110 is restarted after
having been previously connected to the VPN, it relies on
configuration data stored in its non-volatile memory to simplify
the startup procedure. For example, management server 130 does not
have to transfer configuration data that is unchanged from that it
previously transferred to the edge device.
[0109] Edge device 110 can be implemented in a variety of ways. In
one embodiment, the modules shown in FIG. 3 are code and data
modules that control execution of a general purpose processor in
edge device 110. In alternative embodiments, a special-purpose
processor or other hardware accelerators are used to perform some
of the functions. When edge device 110 is wholly or partially
software based, the edge device includes a program storage, such as
a magnetic disk or non-volatile semiconductor storage, for holding
the software. Optionally, management server 130 can securely
transfer software updates to the edge device to alter its behavior,
for example to fix bugs, add functionality, or the track changing
communication protocols.
[0110] Referring to FIGS. 6A and 6B, alternative embodiments of
edge device 110 do not necessarily use a separate hardware device
to implement similar functionality. Referring to FIG. 6A, a
software-based edge software module 610 implements similar
functionality as the modules shown in FIG. 3. In the alternative
embodiment shown in FIG. 6A, local interface module 310 interfaces
with an IP layer of a software protocol stack 612 executing on
computer 120. External interface module 320 interfaces with a
physical communication link coupled to the computer, for example, a
10 Base-T Ethernet link or a serial RS-232 link. Communication
interface 615 then provides an interface between the computer and
the ISP POP. For example, communication interface 615 can be a
cable modem coupled to the ISP over a cable television network.
[0111] Referring to FIG. 6B, in another alternative embodiment, the
functionality of edge device 110 is implemented on a coprocessor
board as an edge hardware module 620 that is hosted in a computer
120. In FIG. 6B, edge hardware module 620 has only a single
connection to local subnetwork 125. Communication between another
computer 120 and an edge device 110 at another location on the
Internet passes from that computer, to edge hardware module 620,
and then back over local subnetwork 125 to communication interface
625. Communication interface 625 may be a standard device such as a
router or a firewall device that is used to couple subnetwork 125
to the Internet.
[0112] Referring back to FIG. 2, another alternative embodiment
combines the functionality of edge device 110 and communication
interface 214 into a single device 205. An example of such a single
device might accept a 10 Base-T connection from a computer, and
connect directly to a cable television network, providing both the
functionality of the edge device and a cable modem in a single
device.
[0113] Referring to FIG. 7, a network device 710 is used in
conjunction with edge devices 110 of the type described above to
provide connectivity through tunnels 115 to form the VPN. Network
device 710 is similar to edge device 110, as shown in FIG. 3,
although it does not necessarily have a local interface module 310.
Instead, it simply routes traffic between tunnels 115 that are
connected to it without necessarily servicing a local subnetwork.
One or more network devices 710 can be used to reduce the number of
tunnels that are needed as compared to a fully meshed VPN. Also,
network device 710 can provide redundant tunnels 115 that may be
dynamically chosen by routers 360 (FIG. 3) depending on routing
data related to the different tunnels.
[0114] In yet another embodiment, edge devices 110 and network
devices 710 can concurrently implement multiple segregated VPNs.
The VPNs are segregated in that a router 360 does not pass packets
between the different segregated VPNs. Referring to FIG. 8, three
edge devices 810, which are similar to edge devices 110 but with
the ability to handle multiple VPNs, and a network device 820,
which is similar to network device 710 (FIG. 7), form two VPNs.
Tunnels 815 are used in a first VPN, while tunnels 825 are used in
a second VPN. Network device 820 and edge devices 810 do not route
data or pass routing information from a tunnel 815 to a tunnel 825,
thereby maintaining the segregation. In this arrangement, network
devices 710 can optionally be used to establish a management VPN
that is used to manage the network devices themselves, separate
from the VPNs set up for particular customers.
[0115] Referring still to FIG. 8, a centralized firewall 830
provides restricted access for computers 840 over Internet 100 to a
VPN. Centralized firewall 830 maintains tunnels 835 to one or more
edge devices 810 or network devices 820, and is centrally managed
from a management server 130 (not shown in FIG. 8). In this way, a
high capacity firewall computer can be used rather than hosting a
firewall at a customer premises. In alternative embodiments of a
centralized firewall 830, restricted access can be concurrently
provided to a number of VPNs.
[0116] In other embodiments, other shared resources can be
centralized and accessed over one or more VPNs, including for
example, communication gateway servers or data servers with
restricted access.
[0117] While the invention has been described in detail with
reference to exemplary embodiments thereof, it will be apparent to
one skilled in the art that various changes can be made, and
equivalents employed, without departing from the scope of the
invention. The foregoing description of the preferred embodiments
of the invention has been presented for purposes of illustration
and description. It is not intended to be exhaustive or to limit
the invention to the precise form disclosed, and modifications and
variations are possible in light of the above teachings or may be
acquired from practice of the invention. The embodiments were
chosen and described in order to explain the principles of the
invention and its practical application to enable one skilled in
the art to utilize the invention in various embodiments as are
suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the claims appended hereto,
and their equivalents. The entirety of each of the aforementioned
documents is incorporated by reference herein.
* * * * *