WO2001043369A2

WO2001043369A2 - Private network using a public-network infrastructure

Info

Publication number: WO2001043369A2
Application number: PCT/US2000/042728
Authority: WO
Inventors: Germano Caronni; Amit Gupta; Tom R. Markson; Sandeep Kumar; Christoph L. Schuba; Glenn C. Scott
Original assignee: Sun Microsystems, Inc.
Priority date: 1999-12-10
Filing date: 2000-12-11
Publication date: 2001-06-14
Also published as: WO2001043369A3; AU4312001A

Abstract

Methods and systems consistent with the present invention provide a Supernet, a private network constructed out of components from a public-network infrastructure. Supernet nodes can be located on virtually any device in the public network (e.g., the Internet), and both their communication and utilization of resources occur in a secure manner. As a result, the users of a Supernet benefit from their network infrastructure being maintained for them as part of the public-network infrastructure, while the level of security they receive is similar to that of a private network. Additionally, the nodes of the Supernet are not geographically restricted in that they can be connected to the Supernet from virtually any portal to the Internet in the world.

Description

PRIVATE NETWORK USING A PUbLIC₌NETWORK INFRASTRUCTURE

FIELD OF THE INVENTION The present invention relates generally to data processing systems and. more particularly, to a private network using a public-network infrastructure.

BACKGROUND OF THE INVENTION

As part of their day-to-day business, many organizations require an enterprise

network, a private network with lease lines, dedicated channels, and network connectivity devices, such as routers, switches, and bridges. These components, collectively known as

the network's "infrastructure," are very expensive and require a staff of information

technology personnel to maintain them. This maintenance requirement is burdensome on

many organizations whose main business is not related to the data processing industry (e.g.,

a clothing manufacturer) because they are not well suited to handle such data processing needs.

Another drawback to enterprise networks is that they are geographically restrictive.

The term "geographically restrictive" refers to the requirement that if a user is not physically located such that they can plug their device directly into the enterprise network, the user

cannot typically utilize it. To alleviate the problem of geographic restrictiveness, virtual private networks have been developed.

In a virtual private network (VPN), a remote device or network connected to the

Internet may connect to the enterprise network through a firewall. This allows the remote device to access resources on the enterprise network even though it may not be located near any component of the enterprise network. For example, Fig. 1 depicts a VPN 100, where enteφrise network 102 is connected to the Internet 104 via firewall 106. By using VPN 100.

a remote device D, 108 may communicate with enteφrise network 102 via Internet 104 and firewall 106. Thus, D, 108 may be plugged into an Internet portal virtually anywhere within the world and make use of the resources on enteφrise network 102.

To perform this functionality, D, 108 utilizes a technique known as tunneling to

ensure that the communication between itself and enteφrise network 102 is secure in that it

cannot be viewed by an interloper. "Tunneling" refers to encapsulating one packet inside

another when packets are transferred between end points (e.g., D, 108 and VPN software 109

running on firewall 106). The packets may be encrypted at their origin and decrypted at their

destination. For example, Fig. 2A depicts a packet 200 with a source Internet protocol (IP)

address 202, a destination IP address 204, and data 206. It should be appreciated that packet

200 contains other information not depicted, such as the source and destination port. As shown in Fig. 2B, the tunneling technique forms a new packet 208 out of packet 200 by encrypting it and adding both a new source IP address 210 and a new destination IP address

212. In this manner, the contents of the original packet (i.e., 202, 204, and 206) are not

visible to any entity other than the destination. Referring back to Fig. 1 , by using tunneling, remote device D, 108 may communicate and utilize the resources of the enteφrise network 102 in a secure manner.

Although VPNs alleviate the problem of geographic restrictiveness, they impose

significant processing overhead when two remote devices communicate. For example, if remote device D, 108 wants to communicate with remote device D₂ 1 10, D, sends a packet using tunneling to VPN software 109, where the packet is decrypted and then transferred to the enteφrise network 102. Then, the enteφrise network 102 sends the packet to VPN

software 109, where it is encrypted again and transferred to D₂ Given this processing overhead, it is burdensome for two remote devices to communicate in a VPN environment. It is therefore desirable to alleviate the need of organizations to maintain their own network

infrastructure as well as to improve communication between remote devices.

SUMMARY OF THE INVENTION Methods and systems consistent with the present invention provide a private network

that uses components from a public-network infrastructure. Nodes of the private network

can be located on virtually any device in the public network (e.g., the Internet), and both their

communication and utilization of resources occur in a secure manner. As a result, the users

of this private network benefit from their network infrastructure being maintained for them as part of the public-network infrastructure, while the level of security they receive is similar to or even stronger than that provided by conventional private networks. Additionally, the

nodes of the private network are not geographically restricted in that they can be connected to the private network from virtually any portal to the Internet in the world.

In accordance with the puφose of the invention as embodied and broadly described herein, a method is provided in a public network. This method establishes in the public network a private network containing at least three nodes such that each node communicates in a secure manner by using an encryption key shared by the at least three nodes and by using

an encryption algorithm. Also, this method sends communications among the three nodes in the secure manner by using the shared encryption key and the encryption algorithm. In another implementation, a method is provided in a public network. This method

establishes in the public network a private network containing a plurality of nodes retlectins communication end points and a plurality of channels interconnecting the nodes, wherein one

of the channels has at least three nodes. Additionally, this method sends communications between the at least three nodes over the one channel.

In yet another implementation, a method is provided in a public network. This

method establishes in the public network a private network having a plurality of nodes and

having a security manager, each of the plurality of nodes having a key for use with an

encryption algorithm for communicating over the network in a secure manner. The security

manager receives a request for a new node to join the private network, generates a new key

for use in communicating in the secure manner in the network, and sends the new key to the

new node and the plurality of nodes.

In accordance with systems consistent with the present invention, a computer is connected to a public network infrastructure over which a private network operates. The private network has a plurality of nodes, and the computer comprises a memory and a processor. The memory contains one of the plurality of nodes for communicating over the private network. The memory also contains a security layer that receives from the one node communications containing internal addresses that are suitable for use in communicating within the private network, that translates the internal addresses into external addresses that are suitable for use in communicating over the public-network infrastructure, that encrypts the communications, and that transmits the communications over the public network to destinations of the communications. The processor runs the one node and the security layer. BRIEF DESCRIPTION OF THE DRAWINGS

This invention is pointed out with particularity in the appended claims. The above

and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: Fig. 1 depicts a conventional virtual private network (VPN) system;

Fig. 2A depicts a conventional network packet;

Fig. 2B depicts the packet of Fig. 2A after it has been encrypted in accordance with

a conventional tunneling technique;

Fig. 3 depicts a data processing system suitable for use with methods and systems consistent with the present invention;

Fig. 4 depicts the nodes depicted in Fig. 3 communicating over multiple channels;

Fig. 5 depicts two devices depicted in Fig. 3 in greater detail;

Figs. 6A and 6B depict a flow chart of the steps performed when a node joins a VPN in a manner consistent with the present invention; Fig. 7 depicts a flow chart of the steps performed when sending a packet from a node of the VPN in a manner consistent with the present invention;

Fig. 8 depicts a flow chart of the steps performed when receiving a packet by a node of the VPN in a manner consistent with the present invention; and

Fig. 9 depicts a flow chart of the steps performed when logging out of a VPN in a manner consistent with the present invention. DETAILED DESCRIPTION

Methods and systems consistent with the present invention provide a "Supernet,"

which is a private network that uses components from a public-network infrastructure. A

Supernet allows an organization to utilize a public-network infrastructure for its enteφrise

network so that the organization no longer has to maintain a private network infrastructure; instead, the organization may have the infrastructure maintained for them by one or more

service providers or other organizations that specialize in such connectivity matters. As

such, the burden of maintaining an enteφrise network is greatly reduced. Moreover, a

Supemet is not geographically restrictive, so a user may plug their device into the Internet

from virtually any portal in the world and still be able to use the resources of their private

network in a secure and robust manner.

Overview

Fig.3 depicts a data processing system 300 suitable for use with methods and systems consistent with the present invention. Data processing system 300 comprises a number of

devices, such as computers 302-312, connected to a public network, such as the Internet 314.

A Supernet's infrastructure uses components from the Internet because devices 302, 304, and 312 contain nodes that together form a Supernet and that communicate by using the infrastructure of the Internet. These nodes 316, 318, 320, and 322 are communicative entities (e.g., processes) running within a particular device and are able to communicate among themselves as well as access the resources of the Supernet in a secure manner. When communicating among themselves, the nodes 316, 318, 320, and 322 serve as end points for the communications, and no other processes or devices that are not part of the Supernet are able to communicate with the Supernet's nodes or utilize the Supernet's resources. The Supernet also includes an administrative node 306 to administer to the needs of the Supernet It should be noted that since the nodes of the Supernet rely on the Internet for

connectivity, if the device on which a node is running relocates to another geographic

location, the device can be plugged into an Internet portal and the node running on that

device can quickly resume the use of the resources of the Supernet. It should also be noted

that since a Supernet is layered on top of an existing network, it operates independently of

the transport layer. Thus, the nodes of a Supernet may communicate over different

transports, such as IP, IPX, X.25, or ATM, as well as different physical layers, such as RF communication, cellular commμnication, satellite links, or land-based links.

As shown in Fig. 4, a Supemet includes a number of channels that its nodes 316-322 can communicate over. A "channel" refers to a collection of virtual links through the public- network infrastructure that connect the nodes on the channel such that only these nodes can communicate over it. A node on a channel may send a message to another node on that channel, known as a unicast message, or it can send a message to all other nodes on that

channel, known as a multicast message. For example, channel 1 402 connects node A 316 and node C 320, and channel 2404 connects node B 318, node C 320, and node D 322. Each Supernet has any number of preconfigured channels over which the nodes on that channel can communicate. In an alternative embodiment, the channels are dynamically defined.

In addition to communication, the channels may be used to share resources. For example, channel 1 402 may be configured to share a file system as part of node C 320 such that node A 316 can utilize the file system of node C in a secure manner. In this case, node C 320 serves as a file system manager by receiving file system requests (e.g.. open, close,

read, write, etc.) and by satisfying the requests by manipulating a portion of the secondarv

storage on its local machine. To maintain security, node C 320 stores the data in an

encrypted form so that it is unreadable by others. Such security is important because the

secondary storage may not be under the control of the owners of the Supemet, but may instead be leased from a service provider. Additionally, channel 2 404 may be configured

to share the computing resources of node D 322 such that nodes B 318 and C 320 send code

to node D for execution. By using channels in this manner, resources on a public network

can be shared in a secure manner.

A Supernet provides a number of features to ensure secure and robust communication among its nodes. First, the system provides authentication and admission control so that

nodes become members of the Supernet under strict control to prevent unauthorized access. Second, the Supernet provides communication security services so that the sender of a

message is authenticated and communication between end points occurs in a secure manner by using encryption. Third, the system provides key management to reduce the possibility

of an intruder obtaining an encryption key and penetrating a secure communication session. The system does so by providing one key per channel and by changing the key for a channel whenever a node joins or leaves the channel. Alternatively, the system may use a different

security policy.

Fourth, the system provides address translation in a transparent manner. Since the Supernet is a private network constructed from the infrastructure of another network, the Supemet has its own internal addressing scheme, separate from the addressing scheme of the underlying public network. Thus, when a packet from a Supemet node is sent to another Supernet node, it travels through the public network. To do so, the Supe et performs

address translation from the internal addressing scheme to the public addressing scheme and

vice versa. To reduce the complexity of Supemet nodes, system-level components of the

Supemet perform this translation on behalf of the individual nodes so that it is transparent

to the nodes. Another benefit of the Supernet's addressing is that it uses an IP-based internal

addressing scheme so that preexisting programs require little modification to run within a

Supemet.

Lastly, the Supe et provides operating system-level enforcement of node

compartmentalization in that an operating system-level component treats a Supemet node running on a device differently than it treats other processes on that device. This component

(i.e., a security layer in a protocol stack) recognizes that a Supemet node is part of a

Supemet, and therefore, it enforces that all communications to and from this node travel through the security infrastructure of the Supemet such that this node can communicate with other members of the Supemet and that non-members of the Supemet cannot access this node. Additionally, this operating system-level enforcement of node compartmentalization allows more than one Supemet node to run on the same machine, regardless of whether the nodes are from the same Supemet, and allows nodes of other networks to run on the same

machine as a Supemet node. Implementation Details

Fig. 5 depicts administrative machine 306 and device 302 in greater detail, although the other devices 304 and 308-312 may contain similar components. Device 302 and

administrative machine 306 communicate via Internet 314. Each device contains similar

components, including a memory 502, 504; secondary storage 506, 508: a central processing

unit (CPU) 510, 512; an input device 514, 516; and a video display 518, 520. One skilled

in the art will appreciate that these devices may contain additional or different components.

Memory 504 of administrative machine 306 includes the S ASD process 540, VARPD

548, and KMS 550 all running in user mode. That is, CPU 512 is capable of running in at

least two modes: user mode and kernel mode. When CPU 512 executes programs running in user mode, it prevents them from directly manipulating the hardware components, such

as video display 518. On the other hand, when CPU 512 executes programs running in

kernel mode, it allows them to manipulate the hardware components. Memory 504 also contains a VARPDB 551 and a TCP/IP protocol stack 552 that are executed by CPU 512

running in kernel mode. TCP/IP protocol stack 552 contains a TCP/UDP layer 554 and an IP layer 556, both of which are standard layers well known to those of ordinary skill in the art. Secondary storage 508 contains a configuration file 558 that stores various configuration-related information (described below) for use by SASD 540.

S ASD 540 represents a Supemet: there is one instance of an SASD per Supemet, and it both authenticates nodes and authorizes nodes to join the Supemet. VARPD 548 has an associated component, VARPDB 551, into which it stores mappings of the internal Supemet addresses, known as a node IDs, to the network addresses recognized by the public-network infrastructure, known as the real addresses. The "node ID" may include the following: a

Supemet ID (e.g., Ox 123 ), reflecting a unique identifier of the Supemet, and a virtual address, comprising an IP address (e.g., 10.0.0.1 ). The "real address" is an IP address (e.g., 10.0.0.2) that is globally unique and meaningful to the public-network infrastructure. In a Supernet. one VARPD ns on each machine, and it may play two roles. First, a VARPD may act as

a server by storing all address mappings for a particular Supemet into its associated

VARPDB. Second, regardless of its role as a server or not, each VARPD assists in address translation for the nodes on its machine. In this role, the VARPD stores into its associated

VARPDB the address mappings for its nodes, and if it needs a mapping that it does not have,

it will contact the VARPD that acts as the server for the given Supemet to obtain it.

KMS 550 performs key management by generating a new key every time a node joins

a channel and by generating a new key every time a node leaves a channel. There is one KMS per channel in a Supemet.

To configure a Supemet, a system administrator creates a configuration file 558 that

is used by SASD 540 when starting or reconfiguring a Supemet. This file may specify: (1) the Supemet name, (2) all of the channels in the Supemet, (3) the nodes that communicate over each channel, (4) the address of the KMS for each channel, (5) the address of the VARPD that acts as the server for the Supemet, (6) the user IDs of the users who are authorized to create Supemet nodes, (7) the authentication mechanism to use for each user

of each channel, and (8) the encryption algorithm to use for each channel. Although the configuration information is described as being stored in a configuration file, one skilled in 01/43369 ₁₂

the art will appreciate that this information may be retrieved from other sources, such as databases or interactive configurations.

After the configuration file is created, it is used to start a Supernet. For example, when starting a Supemet, the system administrator first starts SASD. which reads the

configuration information stored in the configuration file. Then, the administrator starts the

VARPD on the administrator's machine, indicating that it will act as the server for the

Supemet and also starts the KMS process. After this processing has completed, the Supemet

is ready for nodes to join it.

Memory 502 of device 302 contains SNIogin script 522, SNlogout script 524,

VARPD 526, KMC 528, KMD 530, and node A 522, all running in user mode. Memory 502

also includes TCP/IP protocol stack 534 and VARPDB 536 running in kernel mode.

SNIogin 522 is a script used for logging into a Supemet. Successfully executing this script results in a Unix shell from which programs (e.g., node A 522) can be started to run within the Supemet context, such that address translation and security encapsulation is performed transparently for them and all they can typically access is other nodes on the

Supemet. Alternatively, a parameter may be passed into SNIogin 522 that indicates a particular process to be automatically run in a Supemet context. Once a program is running in a Supemet context, all programs spawned by that program also run in the Supemet context, unless explicitly stated otherwise. SNlogout 524 is a script used for logging out of a Supemet. Although both SNIogin 522 and SNlogout 524 are described as being scripts, one skilled in the art will appreciate that their processing may be performed by another form of software. VARPD 526 performs address translation between node IDs and real addresses. KMC 528 is the key management component for each node that receives updates whenever

the key for a channel ("the channel key") changes. There is one KMC per node per channel. KMD 530 receives requests from SNSL 542 of the TCP IP protocol stack 534 when a packet is received and accesses the appropriate KMC for the destination node to retrieve the

appropriate key to decrypt the packet. Node A 532 is a Supemet node running in a Supemet

context.

TCP/IP protocol stack 534 contains a standard TCP/UDP layer 538. two standard IP

layers (an inner IP layer 540 and an outer IP layer 544), and a Supemet security layer (SNSL) 542, acting as the conduit for all Supemet communications. To conserve memory, both inner

IP layer 540 and outer IP layer 544 may share the same instance of the code of an IP layer.

SNSL 542 performs security functionality as well as address translation. It also caches the

most recently used channel keys for ten seconds. Thus, when a channel key is needed, SNSL 542 checks its cache first, and if it is not found, it requests KMD 530 to contact the appropriate KMC to retrieve the appropriate channel key. Two IP layers 540, 544 are used in the TCP/IP protocol stack 534 because both the internal addressing scheme and the

external addressing scheme are IP-based. Thus, for example, when a packet is sent, inner IP layer 540 receives the packet from TCP UDP layer 538 and processes the packet with its node ID address before passing it to the SNSL layer 542, which encrypts it, prepends the real source IP address and the real destination IP address, and then passes the encrypted packet

to outer IP layer 544 for sending to the destination.

SNSL 542 utilizes VARPDB 536 to perform address translation. VARPDB stores all of the address mappings encountered thus far by SNSL 542. If SNSL 542 requests a mapping that VARPDB 536 does not have, VARPDB communicates w ith the VARPD 526 on the local machine to obtain the mapping. VARPD 526 will then contact the VARPD that acts as the server for this particular Supemet to obtain it.

Although aspects of the present invention are described as being stored in memory.

one skilled in the art will appreciate that these aspects can also be stored on or read from

other types of computer-readable media, such as secondary storage devices, like hard disks,

floppy disks, or CD-ROM; a carrier wave from a network, such as the Internet; or other forms of RAM or ROM either currently known or later developed. Additionally, although

a number of the software components are described as being located on the same machine,

one skilled in the art will appreciate that these components may be distributed over a number

of machines.

Figs. 6A and 6B depict a flow chart of the steps performed when a node joins a Supemet. The first step performed is that the user invokes the SNIogin script and enters the Supemet name, their user ID, their password, and a requested virtual address (step 602). Of course, this information depends on the particular authentication mechanism used. Upon

receiving this information, the SNIogin script performs a handshaking with SASD to authenticate this information. In this step, the user may request a particular virtual address to be used, or alternatively, the SASD may select one for them. Next, if any of the information in step 602 is not validated by SASD (step 604), processing ends. Otherwise,

upon successful authentication, SASD creates an address mapping between a node ID and the real address (step 606). In this step, SASD concatenates the Supemet ID with the virtual address to create the node ID, obtains the real address of the SNIogin script by querying network services in a well-known manner, and then registers this information with the

VARPD that acts as the server for this Supemet. This VARPD is identified in the configuration file.

After creating the address mapping, SASD informs the KMS that there is a new

Supemet member that has been authenticated and admitted (step 608). In this step, SASD

sends the node ID and the real address to KMS who then generates a key ID, a key for use

in communicating between the node's KMC and the KMS ("a node key"), and updates the

channel key for use in encrypting traffic on this particular channel (step 610). Additionally,

KMS sends the key ID and the node key to SASD and distributes the channel key to all

KMCs on the channel as a new key because a node has just been added to the channel.

SASD receives the key ID and the node key from KMS and returns it to SNIogin (step 612).

After receiving the key ID and the node key from SASD, SNIogin starts a KMC for this node and transmits to the KMC the node ID, the key ID, the node key, the address of the VARPD that acts as the server for this Supemet, and the address of KMS (step 614). The KMC then registers with the KMD indicating the node it is associated with, and KMC registers with

KMS for key updates (step 616). When registering with KMS, KMC provides its address so that it can receive updates to the channel key via the Versakey protocol. The Versakey protocol is described in greater detail in IEEE Journal on Selected Areas in Communication. Vol. 17, No. 9, 1999, pp. 1614-1631. After registration, the KMC will receive key updates whenever a channel key changes on one of the channels that the node communicates over. Next. SNIogin configures SNSL (step 618 in Fig. 6B). In this step. SNIogin indicates which encryption algorithm to use for this channel and which authentication algorithm to

use. both of which are received from the configuration file via SASD. SNSL stores this information in an access control list. In accordance with methods and systems consistent

with present invention, any of a number of well-known encryption algorithms may be used, including the Data Encryption Standard (DES), Triple-DES, the International Data

Encryption Algorithm (IDEA), and the Advanced Encryption Standard (AES). Also, RC2,

RC4, and RC5 from RSA Incoφorated may be used as well as Blowfish from

Counteφane.com. Additionally, in accordance with methods and systems consistent with

the present invention, any of a number of well-known authentication algorithms may be used, including Digital Signatures, Kerberos, Secure Socket Layer (SSL), and MD5, which is

described in RFC 1321 of the Internet Engineering Task Force, April, 1992.

After configuring SNSL, SNIogin invokes an operating system call, SETVIN, to cause the SNIogin script to run in a Supemet context (step 620). In Unix, each process has a data structure known as the "proc structure" that contains the process ID as well as a pointer

to a virtual memory description of this process. In accordance with methods and systems consistent with the present invention, the channel IDs indicating the channels over which the

process communicates as well as its virtual address for this process are added to this structure. By associating this information with the process, the SNSL layer can enforce that this process runs in a Supernet context. Although methods and systems consistent with the present invention are described as operating in a Unix environment, one skilled in the art will appreciate that such methods and systems can operate in other environments. After the SNIogin script runs in the Supemet context, the SNIogin script spawns a Unix program, such

as a Unix shell or a service daemon (step 622). In this step, the SNIogin script spawns a Unix shell from which programs can be run by the user. All of these programs will thus run in the Supemet context until the user runs the SNlogout script.

Fig. 7 depicts a flow chart of the steps performed when sending a packet from node

A. Although the steps of the flow chart are described in a particular order, one skilled in the

art will appreciate that these steps may be performed in a different order. Additionally,

although the SNSL layer is described as performing both authentication and encryption, this

processing is policy driven such that either authentication, encryption, both, or neither may

be performed. The first step performed is for the SNSL layer to receive a packet originating from node A via the TCP/UDP layer and the inner IP layer (step 702). The packet contains

a source node ID, a destination node ID, and data. The SNSL layer then accesses the VARPDB to obtain the address mapping between the source node ID and the source real address as well as the destination node ID and the destination real address (step 704). If they are not contained in the VARPDB because this is the first time a packet has been sent from this node or sent to this destination, the VARPDB accesses the local VARPD to obtain the

mapping. When contacted, the VARPD on the local machine contacts the VARPD that acts as the server for the Supemet to obtain the appropriate address mapping.

After obtaining the address mapping, the SNSL layer determines whether it has been configured to communicate over the appropriate channel for this packet (step 706). This configuration occurs when SNIogin runs, and if the SNSL has not been so configured, processing ends. Otherwise, SNSL obtains the channel key to be used for this channel (step 708). The SNSL maintains a local cache of keys and an indication of the channel to which each key is associated. Each channel key is time stamped to expire in ten seconds, although this time is configurable by the administrator. If there is a key located in the cache for this

channel, SNSL obtains the key. Otherwise, SNSL accesses KMD which then locates the

appropriate channel key from the appropriate KMC. After obtaining the key, the SNSL layer

encrypts the packet using the appropriate encryption algorithm and the key previously

obtained (step 710). When encrypting the packet, the source node ID, the destination node

ID, and the data may be encrypted, but the source and destination real addresses are not, so

that the real addresses can be used by the public network infrastructure to send the packet to

its destination.

After encrypting the packet, the SNSL layer authenticates the sender to verify that it

is the bona fide sender and that the packet was not modified in transit (step 712). In this step, the SNSL layer uses the MD5 authentication protocol, although one skilled in the art will

appreciate that other authentication protocols may be used. Next, the SNSL layer passes the packet to the IP layer where it is then sent to the destination node in accordance with known techniques associated with the IP protocol (step 714).

Fig. 8 depicts a flow chart of the steps performed by the SNSL layer when it receives

a packet. Although the steps of the flow chart are described in a particular order, one skilled in the art will appreciate that these steps may be performed in a different order. Additionally, although the SNSL layer is described as performing both authentication and encryption, this processing is policy driven such that either authentication, encryption, both, or neither may be performed. The first step performed by the SNSL layer is to receive a packet from the network (step 801). This packet contains a real source address and a real destination address that are not encrypted as well as a source node ID, a destination node ID. and data that are encrypted. Then, it determines whether it has been configured to communicate on this

channel to the destination node (step 802). If SNSL has not been so configured, processing

ends. Otherwise, the SNSL layer obtains the appropriate key as previously described (step

804). It then decrypts the packet using this key and the appropriate encryption algorithm

(step 806). After decrypting the packet, the SNSL layer authenticates the sender and

validates the integrity of the packet (step 808), and then it passes the packet to the inner IP

layer for delivery to the appropriate node (step 810). Upon receiving the packet, the inner

IP layer uses the destination node ID to deliver the packet.

Fig. 9 depicts a flow chart of the steps performed when logging a node out of a Supemet. The first step performed is for the user to ran the SNlogout script and to enter a node ID (step 902). Next, the SNlogout script requests a log out from SASD (step 904).

Upon receiving this request, SASD removes the mapping for this node from the VARPD that acts as the server for the Supemet (step 906). SASD then informs KMS to cancel the registration of the node, and KMS terminates this KMC (step 908). Lastly, KMS generates a new channel key for the channels on which the node was communicating (step 910) to provide greater security.

Although the present invention has been described with reference to a preferred embodiment, those skilled in the art will know of various changes in form and detail which may be made without departing from the spirit and scope of the present invention as defined in the appended claims and their full scope of equivalents.

Claims

CLAIMSWhat is claimed is:

1. A method in a public network having a network infrastructure that is used b_\

a private network over which a plurality of nodes communicate, comprising the steps of:

receiving a request from a user to add a new node to the private network, the request

containing an identifier of the private network and an identifier of the user, the new node for

running on a device connected to the network infrastmcture, the device having a system-level

component used for communicating over the private network;

attempting to authenticate the request including the private network identifier and the

user identifier; when the request has been authenticated successfully, generating an address mapping for the new node, the address mapping used

for mapping between an internal address suitable for use in communicating among the

plurality of nodes in the private network and an external address suitable for communicating over the network infrastructure of the public network; configuring, by the system-level component, the new node to be in a context

such that the new node is capable of communicating with the plurality of nodes on the private network; and sending, by the system-level component, a packet from the new node to a destination one of the plurality of nodes on the private network by accessing the address mapping and adding the external address to the packet and by causing delivery of the packet to the destination node to occur in a secure manner.

2. The method of claim 1 wherein the configuring step includes the step of:

preventing senders other than the plurality of nodes from communicating with the new node.

3. The method of claim 1 wherein the step of sending the packet includes the

step of:

encrypting the packet.

4. The method of claim 1 wherein the sending step further includes the step of:

authenticating the new node.

5. The method of claim 1 wherein the destination node has an associated address mapping between an internal address and an external address, and wherein the sending step

further includes the steps of: accessing the address mapping of the destination node; and adding the external address of the destination node to the packet.

6. A method in a public network, comprising the steps of:

establishing in the public network a private network containing at least three nodes such that each node communicates in a secure manner by using an encryption key and an encryption algorithm shared by the three nodes; and

sending communications among the three nodes in the secure manner by using the

shared encryption key and the encryption algorithm.

7. The method of claim 6 wherein the private network contains a plurality of channels for sending the communications.

8. The method of claim 6 wherein each of the communications is sent by a

sending node, and wherein the step of sending communications includes the step of: authenticating the sending node of each of the communications.

9. The method of claim 6 wherein each communication has a first associated address suitable for use in the private network and a second associated address suitable for use in the public network, wherein the sending step includes the step of: for each communication, mapping the first associated address to the second associated address, and using the second associated address to send the communication via the public network.

10. A method in a public network, comprising the steps of:

establishing in the public network a private network containing a plurality of nodes reflecting communication end points and a plurality of channels interconnecting the nodes. wherein one of the channels has at least three nodes; and

sending communications between the at least three nodes over the one channel.

1 1. The method of claim 10 wherein the sending step includes the step of: sending the communications in a secure manner.

12. The method of claim 10 wherein the sending step includes the step of:

encrypting each of the communications.

13. The method of claim 10 wherein each communication has an originating node and wherein the sending step includes the step of: authenticating the originating node of each communication.

14. A method in a public network, comprising the steps of:

establishing in the public network a private network having a plurality of nodes and having a security manager, each of the plurality of nodes having a key for use w ith an

encryption algorithm for communicating over the public network in a secure manner;

receiving a request for a new node to join the private network by the security

manager;

generating a different key for use in communicating in the secure manner in the

public network by the security manager; and

sending the different key to the new node and the plurality of nodes by the security

manager.

15. The method of claim 14 wherein the private network contains a plurality of

channels for communicating.

16. The method of claim 14 further including the steps performed by the security

manager of:

receiving a request for the new node to leave the network;

generating a replacement key to supersede the new key; and

sending the replacement key to the plurality of nodes.

17. A computer connected to a public-network infrastructure over which a private

network operates, the private network having a plurality of nodes, the computer comprising: a memory containing:

one of the plurality of nodes for communicating over the private

network; and

a security layer that receives from the one node communications

containing internal addresses that are suitable for use in communicating within the private

network, that translates the internal addresses into external addresses that are suitable for use

in communicating over the public-network infrastmcture, that encrypts the communications, and that transmits the communications over the public network to destinations of the

communications; and a processor for running the one node and the security layer.

18. The computer of claim 17 wherein the security layer runs in kernel mode.

19. The computer of claim 17 wherein the one node communicates over a

plurality of channels.

20. The computer of claim 17 wherein the security layer prevents senders other than the plurality of nodes from sending communications to the one node.

21. The computer of claim 17 wherein the security layer is part of a protocol

stack.

22. A computer-readable medium containing instructions for controlling a distributed system to perform a method in a public network, the method comprising the steps of: establishing in the public network a private network containing at least three nodes such that each node communicates in a secure manner by using an encryption key shared by

the at least three nodes and by using an encryption algorithm; and

sending communications among the three nodes in the secure manner by using the

shared encryption key and the encryption algorithm.

23. The computer-readable medium of claim 22 wherein the private network contains a plurality of channels for sending the communications.

24. The computer-readable medium of claim 22 wherein each of the communications is sent by a sending node, and wherein the step of sending communications includes the step of: authenticating the sending node of each of the communications.

25. The computer-readable medium of claim 22 wherein each communication has a first associated address suitable for use in the private network and a second associated address suitable for use in the public network, wherein the sending step includes the step of: for each communication, mapping the first associated address to the second

associated address, and using the second associated address to send the communication via

the public network.

26. A computer-readable medium containing instructions for controlling a distributed system to perform a method in a public network, the method comprising the steps

of: establishing in the public network a private network containing a plurality of nodes

reflecting communication end points and a plurality of channels interconnecting the nodes,

wherein one of the channels has at least three nodes; and

sending communications between the at least three nodes over the one channel.

27. The computer-readable medium of claim 26 wherein the sending step includes

the step of: sending the communications in a secure manner.

28. The computer-readable medium of claim 26 wherein the sending step includes

the step of: encrypting each of the communications.

29. The computer-readable medium of claim 26 wherein each communication has an originating node and wherein the sending step includes the step of: authenticating the originating node of each communication.