Abstract:
A virtual private network service provider, wherein virtual private network (“VPN”) software for setting up a virtual private network connection is delivered from a server computer to one or more client computers over a computer network, such as the Internet. Once the VPN software is delivered to the client computers, it can be executed so that data communications are made as virtual private network communications under control of the VPN software. Because the VPN software is stored and maintained on a server computer, and preferably delivered to the various client computers on an as-needed basis, the distribution, integrity and updating of the VPN software is improved because the “master” version of the VPN software can be controlled and revised by merely accessing the server computer system, rather than by attempting to control and revise numerous copies of the VPN software resident on various, scattered client computers.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/297,577, filed Jun. 12, 2001. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to data communications effected over computer networks (e.g., wired networks, wireless networks, virtual networks), and more particularly to virtual private network software for effecting virtual private network type communications over a public computer network. 
     BACKGROUND OF THE INVENTION 
       FIG. 1  is a block diagram of conventional computer network system  100 , which shows two different, conventional ways of communicating computer data over a computer network. Computer network system  100  includes wide area network (“WAN”)  102 , client A computer  110 , client B computer B  120  and server computer  130 . 
     WAN  102  is a conventional wide area network, such as the Internet. WAN  102  is a public network in that access to the network is generally open to the public. WAN  102  preferably includes wireless and wired portions which are preferably integrated at least as seamlessly as technology will allow. 
     Client A computer  110  is a conventional computer, such as a desktop personal computer that includes standard browser software  114  (e.g., Netscape, Microsoft Internet Explorer). (Note, the names Netscape and Microsoft Internet Explorer may be subject to trademark or service mark rights.) Similarly, Client B computer  120  is a conventional computer, such as a desktop personal computer that includes standard browser software  124  (e.g., Netscape, Microsoft Internet Explorer). 
     This browser software (including, as necessary, dialer software, modem software, scripting language interpretation software and the like) allows the computers to set up connections NLC (see  FIG. 1 ) over the WAN. Typically, these connections do not allow the computers to receive unsolicited communications, but rather, the computers can receive only communications that they solicit. (See double arrows marked NLC terminating at reference numerals  114  and  124  and definition of “unsolicited-input connection” below in the Specially Defined Terms section of this document.) Through the connection NLC, the computer&#39;s browser can specifically request and then receive computer data from other computers that are in data communication with WAN  102 . By establishing connection NLC, which does not accept unsolicited data, the computer can communicate over WAN  102  without concern that it will be bombarded with unsecure, unwanted or even harmful computer data (e.g., a virus) because connection NLC will categorically refuse to receive any computer data communications beyond those it has previously requested. 
     While this type of solicited-input-only connection is favorable from a safety standpoint, the connection is somewhat limited because it cannot accept unsolicited data. For example, browser software  114  of client A computer  110  cannot communicate directly with browser  124  of client B computer system. Each of these browsers communicates data exclusively over solicited-input-only connections NLC. Accordingly, neither browser can listen for or receive such requests, so no computer data ever gets exchanged. If all connections to WAN  102  were solicited-input-only connections, then there would be no data communication whatsoever, over this computer network. 
     However, some computers have the software necessary to establish unsolicited-input connections LC. For example, server computer  130  is a conventional server computer with a conventional listening connection to WAN  102 . Server computer  130  listens for and receives requests for computer data from the browsers of various client computers (e.g., client A computer  110 , client B computer  120 ), and sends back appropriate computer data, via WAN  102 , in response to the various requests. For example the requested computer data may be a hypertext mark-up language (“HTML”) code for generating a web page. 
     Also, server computer  130  can be used to allow the operator of client A computer  110  to communicate with the operator of client B computer  120 . For example, if client A computer  110  may communicate with server computer  130  to establish an email account on server  130 . In this case, client B computer  120  can use the solicited-input-only connection of its browser software to upload computer data (as email messages and/or attachments), through the unsolicited-input connection of server computer  130 , to a storage device (not separately shown) in the server computer. After the computer data is stored and present at the server computer, client A computer can request and receive this computer data through the solicited-input-only connection of its browser software  114 . In this way, client A computer and client B computer can communicate their data through the solicited-data-only connections of their respective browsers. 
     Now, while the server computer has a unsolicited-data-only connection, it is noted that the server computer will not indiscriminately respond to all incoming, unsolicited communications. Rather, the server may implement sophisticated techniques for attempting to sort out the desirable requests to upload and download computer data to the server computer. Firewall software is one example of such a sophisticated technique. It should be borne in mind that WAN  102  is a public network, so a great many parties may accidentally or purposely send communications to server computer  130 . 
     While many of these communications will be well-intended and appropriate communications (e.g., email correspondence), some of the communications will be malformed, misdirected, and/or malicious. For example, a malicious communication may be intended and designed to get server computer  130  to download all of its data to a snoop, hacker or other unauthorized party. Server computer  130  is preferably equipped with software to identify such malicious communications and to prevent any unauthorized transmissions or computer actions. 
     However, because server  130  is connected to a public network, and because it is very difficult to identify and stop all malicious communications, the security of the standard client-server architecture explained above is limited in the security and data integrity. In recognition of this fact, certainly highly sensitive communications (e.g., communications containing credit card information, communications containing medical information) are not typically communicated using the standard type of browser-driven network communication explained above. One alternative method of network communication, which is more secure, will now be explained with further reference to  FIG. 1 . 
     As shown in  FIG. 1 , client A computer  110  has additionally been equipped with conventional virtual private network (“VPN”) software  112 . Similarly, client B computer has been equipped with VPN software  122 . This is conventionally accomplished by putting the VPN software on a CD ROM, or other removable storage device, physically bringing the CD ROM to each client computer and copying the VPN software to a permanent storage device (e.g., hard disk drive) present at each computer. 
     Once the VPN is installed at client A computer  110  and client B computer  120 , then these two computers can communicate in a more secure manner. More particularly, most VPN software is structured to accept only authorized communications. For example, many conventional VPN software systems encrypt and decrypt data using algorithms and encryptions keys present in or generated by the VPN software. Additionally, the VPN software may allow a client computer to establish a sort of unsolicited-input connection such that client computers can communicate more directly with each other over a public network. (When the client computers can communicate directly, it may be something of a misnomer to call them “client” computers.) 
     The VPN software affects a “virtual” private network because the general public will still have access to the telephone lines and other communication links of the WAN. However, the VPN software can structure the data of its communication so that they are harder to access and/or interpret, and so that it is more difficult to send unauthorized data through the VPN software connection. In other words, the VPN software at both ends of the communication makes it difficult for the general public (with WAN access) to cause any mischief with respect to the data communications sent over the WAN under control of the VPN software. 
     A third type of conventional computer network communication will now be explained with reference to  FIG. 2 . More particularly,  FIG. 2  is a block diagram of network computer system  200  for making network communications by proxy. Computer system  200  includes WAN  202 , local area network (“LAN”)  204 , LAN server computer  210  and client C computer. Again, WAN is a public network for making network communications over long distances. WAN  202  is preferably the Internet. WAN server computer  230  is a conventional server computer and is similar to server computer  130  discussed above. 
     LAN server computer  210 , LAN  204  and client C computer  220  make up a local area network. The local area network allows LAN server computer  210  and client C computer to mutually communicate computer data. For example, LAN networks are a common architecture for organizing the various computers in a business office. If the LAN is a private network, as LAN&#39;s often are, then there is a relatively high degree of security because only personnel with access to the computers in the business office can access the network for unauthorized or destructive reasons. 
     From a security standpoint, it might not be desirable to connect any portion of the LAN to WAN  202 . By connecting the various computers of the LAN to WAN  202 , this opens up the potential for unauthorized communications to come in from the world at large. As such, the security level would decrease down toward the level associated with WAN&#39;s. However, it is often impractical to categorically prevent the computers of the LAN from receiving computer data from the outside world. 
     In order to allow computers of a LAN to receive computer data from the outside world (e.g., the Internet) using their browser software, while still providing a sufficiently high level of security, the communication technology of proxy communication has been developed. In the example of  FIG. 2 , proxy software has been installed on LAN server computer  210  in order to allow proxied computer data communications between client C computer  220  and computers connected to the WAN, such as WAN server computer  230 . 
     Proxied communication technology is conventional and will not be discussed in great detail herein. Generally speaking, proxy software is used to cache information received over a WAN and acts as an intermediary between the WAN and client computers that are in communication with the proxy software (but not otherwise in direct data communication with the WAN). The proxy software holds common and/or recently-used data from the WAN (e.g., WAN server computer  230 ) for client computers in order to provide quicker access and to increase server security. 
     Perhaps more importantly, proxy servers can be constructed to allow client computers to send and receive data communications, when there is a firewall interposed between the client computer and the WAN. For example, this kind of proxy software may open a socket on the proxy computer (e.g., LAN server computer  210 ) and allow data communication with the WAN via the open socket. In this case, the proxy software would allow requests from the browser software of a client computer (e.g., browser software  222  of client C computer  220 ) to go out over the WAN to their intended destination. Often proxy software involves revising the network address specified within an incoming or outgoing data communication so that the client computer and its browser software may act as if it were directly connected to the WAN and its multitude of various WAN servers (e.g., WAN server computer  230 ). 
     To summarize, three conventional ways of making network communications have been described: (1) traditional client-server architecture; (2) VPN communications and (3) proxied communications. As discussed below, the present invention identifies and makes improvements to VPN and/or proxied communication processes and associated software. 
     One conventional device that is used in making computer network communications is called a router, which is a hardware device that connects and forwards data between two separate networks. Many routers also handle errors and keep statistics about the data communications made over the network. Conventional routers can be implemented as hardware, firmware and/or software. Although conventional router software can be transmitted over a network, the installation of such software typically requires some level of user intervention. For example, a download of conventional router software usually requires either an explicit download instruction or a request to use the software. 
     Another conventional device that is used in making computer network communications is called a firewall. Firewalls are devices that are used to block and/or filter data. These devices are commonly used with routers as part of a single component. 
     SUMMARY OF THE INVENTION 
     The present invention recognizes and contemplates some shortcomings or potential problems in the prior art. These shortcomings and potential problems will now be discussed. 
     First, VPN software and/or proxy software is conventionally initially loaded onto “client” computers or LAN server computers by physically bringing a copy of the software to each and every computer where the software is to be loaded and then loading the software. If the copies of the VPN and/or proxy software is stored on a CD ROM or other removable storage device, then these storage devices must be physically shipped to the computers where the software is to be installed. Alternatively, the software maybe preloaded at the time the pertinent computers are manufactured. Both removable media software distribution and software distribution by pre-loading are subject to pervasive logistical issues, costs and difficulties. 
     Second, VPN software and/or proxy software is subject to change over time as ancillary computer and communications technology develops. For example, VPN software made to run well with a first operating system software may not perform as well (or at all) when the first operating system is discarded in deference to a new and improved operating system. In this situation, a revised VPN software, for use with the new and improved operating system, would need to be transported to the affected machines, or the affected machines would need to be shipped to where the revised VPN software was. This burdensome task of revising or replacing VPN and/or proxy software may need to be repeated quite often, especially if the VPN and/or proxy software is to stay current with the ancillary technology, or if there are bugs in the VPN and/or proxy software. 
     Third, the conventional way of distributing VPN and/or proxy software can involve something of a security risk. For example, if CD ROM&#39;s containing a particular VPN software are widely distributed by mail, then there is a potential that some party will seize one of the CD ROM&#39;s and copy the VPN software in an unauthorized manner. While it is true that security mechanisms may be encoded onto the CD ROM to prevent unauthorized copying, but even with these copy prevention mechanisms there are still potential problems: (1) copy prevention features can sometimes be defeated by determined, unauthorized copyists; (2) the copy prevention features complicate the process of encoding and/or using the CD ROM; and (3) the encoded copy prevention features take up “real estate” on the limited CD ROM recording surface. 
     Fourth, the conventional way of distributing VPN and/or proxy software can be limiting insofar as how the software is to be paid for. More particularly, if VPN software manufacturer sends a CD ROM copy of the VPN software to a business customer, then the manufacturer will not readily know how often the VPN software is being used. This makes it difficult to structure payment for the VPN software on a per use basis. While a per use payment structure may or may not be desired by the contracting parties in every instance, it is nice to leave this payment structure open as an option for the times that software sellers and buyers want to effect compensation for the software in that way. 
     Fifth, according to the conventional way of distributing VPN and/or proxy software, the software must be stored permanently at each computer (e.g., LAN server computer) where the software is to be used. For example, valuable hard disk storage space may need to be permanently allocated to VPN and/or proxy software at every machine. 
     Generally speaking, the present invention involves distribution of VPN and/or proxy software from a server computer to various, scattered client computers through a computer network, such as the Internet. In this way, the VPN and/or proxy software must merely be maintained to be current, for on-demand use by authorized parties, at the server computer. The VPN and/or proxy software need not be physically redistributed every time a revision is made in the software code. Also, at least some embodiments of VPN software according to the present invention mandate that the VPN network communications pass through a central server computer as they travel from a source VPN computer system to a destination VPN computer system. 
     At least some embodiments of the present invention may exhibit one or more of the following objects, advantages and benefits: 
     (1) easier and less expensive to initially install VPN and/or proxy software on a plurality of client computers; 
     (2) easier and less expensive to install revised versions of VPN and/or proxy software on a plurality of client computers on an ongoing basis; 
     (3) more frequent VPN and/or proxy software updates are feasible because of the ease of distributing revised versions of software according to the present invention; 
     (4) better supervision and control of the use of VPN and/or proxy software, because the software may be distributed on-demand on an as-needed basis; 
     (5) better accounting of the amount of actual use of VPN and/or proxy software, because the software may be distributed on-demand on an as-needed basis; 
     (6) use of a central server in connection with VPN computer network transmissions allows better tracking of VPN communications; and 
     (7) use of a central server in connection with VPN computer network transmissions allows each VPN client to establish an unsolicited-input connection with the central server computer. 
     According to one aspect of the present invention, a computer network communication system includes a client computer system, a first computer network, and a server computer system. The server computer system includes a storage device and VPN server software. The storage device stores VPN software. The VPN server software communicates the VPN software to the client computer system over the first network. The VPN software being executable by the client computer system to: (1) restructure first-network-unready machine readable data at the client computer system into corresponding first-network-ready machine readable data; and (2) send the first-network-ready data from the client computer system to a destination computer system over the first computer network. 
     According to a further aspect of the present invention, a computer network communication system includes a client computer system, a first computer network, and a server computer system. The server computer system includes a storage device, VPN software stored on the storage device, and VPN server software. The VPN server software communicates the VPN software to a client computer system over the first network. The VPN software is executable by the client computer system. The VPN software includes machine readable instructions and data for causing the client computer to set up an unsolicited-input connection with the first network. The client computer receives first-network-ready machine readable data from the first network over the unsolicited-input connection, regardless of whether the first-network ready data has been requested by the client computer system. 
     According to a further aspect of the present invention, a computer network communication system includes a private computer network, a proxy client computer, a source computer, a public computer network and a server computer system. The source computer is in data communicative connection with the proxy client computer over the private computer network. The source computer is structured to send a first data communication over the private computer network. The first data communication includes destination data indicative of the intended destination of the first data communication. The destination is a location that is not present on the private network. The server computer system is in data communicative connection with the proxy client computer over the public computer network. The server computer system includes a storage device and proxy server software. Proxy software is stored on the storage device. The proxy server software communicates the proxy software to the proxy client computer system over the public network. The proxy software is executable by the proxy client computer system. The proxy software includes machine readable instructions and data for causing the source computer to recognize the proxy client computer as the destination indicated by the destination data and for thereby causing the source computer to send the first data communication to the proxy client computer over the private computer network. According to a further aspect of the present invention, a method of communicating machine readable data over a computer network includes several steps. One step is storing and maintaining VPN software on a VPN server computer system, with the server computer system being in data communication with a public computer network. Another step is downloading a copy of the VPN software from the VPN server computer system to a first client computer system over the public computer network. Another step is downloading a copy of the VPN software from the VPN server computer system to a second client computer system over the public computer network. Another step is restructuring, at the first client computer system under the control of the downloaded VPN software. More particularly, a first data communication of machine readable data, structured according to a first protocol, is restructured into a corresponding second data communication of machine readable data structured according to a second protocol. The first protocol is unsuitable for communication over the public network. The second protocol is suitable for communication over the public computer network. Another step is sending the second data communication from the first client computer system to the second client computer system over the computer network. Another step is restructuring, at the second client computer system under the control of the downloaded VPN software, the second data communication into a corresponding third data communication of machine readable data structured according to a third protocol. The third protocol is unsuitable for communication over the public network. 
     Further applicability of the present invention will become apparent from a review of the detailed description and accompanying drawings. It should be understood that the description and examples, while indicating preferred embodiments of the present invention, are not intended to limit the scope of the invention, and various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given below, together with the accompanying drawings, which are given by way of illustration only, and are not to be construed as limiting the scope of the present invention. In the drawings: 
         FIG. 1  is block diagram showing a first conventional computer network communication system. 
         FIG. 2  is block diagram showing a second conventional computer network communication system. 
         FIG. 3  is a block diagram of a first embodiment of a computer network communication system according to the present invention. 
         FIGS. 4 to 7  are block diagrams illustrating a method of computer network data communication according to the present invention. 
         FIG. 8  is a block diagram of a second embodiment of a computer network communication system according to the present invention. 
         FIG. 9  is a block diagram of a third embodiment of a computer network communication system according to the present invention. 
         FIG. 10  is a flowchart that sets forth a method of computer network data communication according to the present invention. 
         FIG. 11  is a block diagram of a fourth embodiment of a computer network communication system according to the present invention. 
         FIG. 12  is a block diagram of a fifth embodiment of a computer network communication system according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before starting a description of the Figures, instructions for interpreting the words and phrases of this patent document will be provided. More particularly, many jurisdictions allow a patentee to act as its own lexicographer, and thereby allows the patentee to provide instructions in a patent document as to how the words, terms and phrases of the document are to be interpreted as a legal matter. For example, in the United States, the prerogative of the patentee to act as its own lexicographer has been solidly established based on statutory and case law. Accordingly, the following section provides rules for interpreting the words, terms and phrases of this particular patent document. 
     Interpretive Rules 
     Rule 1: There is a “Specially Defined Terms” section set forth below. Only words, terms or phrases that are explicitly defined in the Specially Defined Terms are to be considered to have a special definition, and, of course, the explicit definition provided herein is to serve as the definition for these terms. Accordingly, sources such as the patent specification and extrinsic evidence shall not be used to help define these terms—the explicitly provided definitions shall control. 
     In some cases, the explicit definition will be partial or supplemental in nature. As a hypothetical example, a definition that read “horses include, but are not limited to, ponies” would amount to only a supplemental definition for the term “horses.” In the case of a supplemental definition, any interpretational issues that are not answered by the supplemental definition shall be decided by the rules for non-specially-defined terms set forth below (that is, Rules 2 to 4). 
     Rule 2: If a word, term or phrase is not specially defined, then its definition shall be determined in the first instance by resort to “pre-existing” definitions that can be found in dictionaries and/or technical lexicons that exist as of the time this patent document is filed. (See definition of “dictionaries and technical lexicons” below in the Specially Defined Terms section.) It is acknowledged that dictionaries and technical lexicons often provide alternative definitions. Also, pre-existing definitions provided in different dictionaries and different lexicons often differ and are not always entirely consistent. In these kinds of circumstances, it must be decided which pre-existing definition is in best accordance with this document when read as a whole. Rules 3 and 4, set forth below, provide some guidelines for choosing between alternatives, pre-existing definitions for a word, term or phrase. 
     Rule 3: The role of the specification (other than the Specially Defined Terms section) as an interpretive or definitional aid shall be limited to helping choose between alternative, pre-existing definitions that meet the requirements of Rule 2 (above). 
     Rule 4: The role of extrinsic evidence (e.g., expert witnesses) as an interpretive of definitional aid shall be limited to helping choose between alternative, pre-existing definitions that meet the requirements of Rule 2 (above). 
     Specially Defines Terms 
     the present invention: means at least some embodiments of the present invention; references to various feature(s) of the “present invention” throughout this document do not mean that all claimed embodiments or methods include the referenced feature(s). 
     structured to: this phrase is used in the claims to indicate that some thing X is “structured to” perform some objective Y. This means that X must have appropriate structure to meet the objective Y that occurs after the “structured to” language. It does not mean that the possible structures for X are limited to what is shown in the specification, but rather includes any and all X, now conventional or to be developed in the future, wherein the structure of X allows the X to perform objective Y. (Note that X and Y are used as variables in this definition of “structured to;” in the claims, various things may be recited as the X variable for purposes of applying this definition, and various objectives may be recited as the Y variable.) 
     comprising . . . a; comprising . . . one; comprising . . . x: comprising means including; for example, if a claim recites that an assembly “comprising a” widget, then the claim should be construed to cover assemblies that have one widget or more than one widget, the fact that the assembly includes a widget does not mean that covered assemblies are limited to one widget unless such a limitation is explicitly present in the claim. 
     dictionaries and/or technical lexicons: any document whose primary purpose is the definition of words, terms and/or phrases; on the other hand, documents that merely discuss, explain or provide examples of devices or methods, without purporting to provide definitions of specific words, phrases or terms, are not to be considered as dictionaries and/or technical lexicons. 
     computer network: includes, but is not limited to, wired networks, wireless networks and virtual networks. 
     client computer system: any computer system that can receive data communications over a computer network. 
     server computer system: any computer system that can send data communications over a computer network, including, but not limited to, computer systems that are capable of receiving and responding to unsolicited requests for computer data over a computer network; it is noted that a computer system may simultaneously be both a client computer system and a server computer system according to the definitions set forth herein. 
     VPN: Virtual Private Network; this phrase and associated acronym broadly signify any software that is useful in helping to maintain some level of enhanced privacy for computer network communications and is not limited to specific VPN software or algorithms now conventional. 
     VPNSP: service provider for providing any sort of VPN. 
     DICOM: Digital Imaging and Communications in Medicine. 
     SMTP: Simple Mail Transfer Protocol. 
     SSL: Secure Socket Layer. 
     first protocol/second protocol: this is not limited to situations where the first and second protocols are alternative protocols at the same level; for example the second protocol may be a higher level protocol than the first protocol; in this example of protocols at different levels, the data would be considered to be restructured from a first protocol to a second protocol, even if the addition of the higher level (that is, second) protocol was merely additional data wrapped around or overlaid upon the first protocol data, thereby leaving the first protocol intact in a sense. 
     first type automatic: download occurs without an explicit download instruction from the user. 
     second type automatic: when the user has no reason to be aware that a download is taking place. 
     third type automatic: download occurs without any input from the user beyond a request to use the software (e.g., opening up a VPNSP icon on a desktop display). 
     HTTP: Hyper Text Transfer Protocol. 
     POP: Post Office Protocol. 
     IMAP: Internet Message Access Protocol. 
     TCP/IP: Transmission Control Protocol/Internet Protocol. 
     communication software: software used to exchange information between computers. 
     router software: communication software used to route information between computers. 
     applet: any computer program that cannot run in stand-alone fashion over an operating system; applets include, but are not limited to, applets written in the Java computer language. 
     unsolicited-input connection: Any connection between a computer and a computer network where the computer runs a listener (e.g., a conventional server computer), or at least includes the functionality of a listener at least to the extent that the computer can accept unsolicited input from the network. An example of such functionality is set forth below in connection with  FIGS. 4 to 10 , where a connection is established by issuing GET commands on an open thread. On the other hand, conventional Internet-connected client computers do not typically have unsolicited-data connections, but rather have solicited-data-only connections. Also, unsolicited-input connection may require special software commands and/or hardware to allow unsolicited input. For example, the GET commands of  FIGS. 4 to 7  are used to establish the unsolicited-input connection of that example. However, these GET commands, and other similar commands are not considered to be solicitations because they do not directly solicit any specific communications, but rather merely keep the door open for unsolicited communications from one or more remote sources. 
     Introduction 
     It is proposed to design and build a unique means of providing secure data transfer over public lines, such as the Internet. In recent times, Virtual Private Networks (VPN&#39;s) have served this purpose. A potential problem with VPN&#39;s is that they are costly and difficult to implement; i.e., they require a proprietary hardware and/or software solution to be installed at both the sending and receiving ends of the network. 
     A practical example in the medical community is communication between two remote radiology networks. Medical images are transmitted using a standard called DICOM (“Digital Imaging and Communications in Medicine”). The DICOM standard does not have any intrinsic provisions for security and was intended to be used over internal Local Area Networks (LAN&#39;s) and not Wide Area Networks (WAN&#39;s). In order for patient images from a CT or MRI scanner at an outlying clinic to be transmitted to a central hospital using DICOM, either an expensive dedicated private line would have to be installed, or a VPN setup over a public network to link the two local area networks. Both of these potential solutions require the use of specialized hardware and software (routers, firewalls, etc.). 
     At least some embodiments of the present invention involve provision of a central server (for example: vpnsp.zmed.com) which would serve up a Java based applet within a Web browser. (It is noted that the words “Java” and “zmed” may be subject to trademark rights.) This applet proxies network traffic on the sending end and forward data to a similar receiving applet at the remote destination. Security is maintained through the browser&#39;s built-in SSL encryption. The benefit of this model is that no specialized hardware, nor software, need be installed at either end of the transmission. The only requirement is that web browsers on both the sending and receiving LAN&#39;s have secure Web access via the Internet (or other public network) to the remote server. The remote server supplies the applets. Thus, a secure connection can be made between any two cooperating sites without any consideration of existing firewalls, Internet routes, Network Address Translation (NAT), etc. 
     This general idea is extensible for any type of network traffic and could be referred to as a Virtual Private Network Service Provider (“VPNSP”). A central server on a public network would serve up applets (e.g., Java applets) on demand to readily (freely) available applet players. For example, applet players will often reside on existing hosts inside the respective firewalls. These applet players may be nothing more than Java-enabled Web browsers such as Netscape or Internet Explorer. With this setup, users will be able to create their own VPN&#39;s on the fly and will always have immediate access to the latest applet version. 
     At least some of the embodiments of the present invention involve a single server that serves a single applet within a single Web browser. In this situation, the client can be a source of data, a destination for data, or both a source and a destination for data. Other architectures for implementing the present invention include, but are not limited to: (1) multiple servers that serve a single applet/browser combination; (2) multiple servers that serve multiple applet/browser combinations; and (3) a single server that serves multiple applet/browser combinations. 
     A specific exemplary implementation of the VPNSP concept is a DICOM proxy web client for the medical imaging community. The DICOM proxy web client enables remote facilities to share patient images in the DICOM protocol using nothing more than Web accessible/Java-enabled Web browsers. Both the transmitter and the receiver detect their respective locally accessible proxy applet as a DICOM device. The DICOM traffic is effectively tunneled through the respective Web browsers. The VPNSP software, working in conjunction with the Web browser, mimics (or enables) a conventional DICOM communication device. 
     All of the above is completely feasible using existing browser technology and the right applet and server. However, this unique use of Web browsers is very different from the original intended use (which is to deliver content sent from remote servers). This ease of deployment of the VPN software (via remote server applets using the Service Provider model) is one of the inventive features of at least some embodiments of the present invention. As far as is known to the inventors, all other techniques of “punching” through firewalls from the inside out currently require the implementation of hardware and operating system (OS) specific software—usually at the OS level. This invention is completely hardware and software independent and allows for a single universal applet to be distributed to mutually-remote client computers by the central server. 
     General Implementation (VPNSP) 
     Centralized Internet accessible web server providing: 
     Administration/Account management 
     Signed applets 
     Higher level protocol proxies 
     Caching facilities
         Data flow:       

     User points browser to URL of external web server and logs in. 
     Signed applet is automatically downloaded into the applet player and commences running silently. 
     Signed applet in the browser runs a listening connection on the LAN. The applet is digitally signed in order to have access to local computers resources such as a network port. Without this confirmation, typical applets run in a ‘sandbox’ mode preventing them from accessing the host computer&#39;s network ports, local hard drive, etc. For example, the listening connection may be implemented by running a listener on a single TCP/IP port on the LAN. 
     Forwards all connections (traffic on listened port) to central Internet server via the existing HTTP connection. 
     Central server authenticates connection and routes traffic based on an incoming source and destination handle. This handle can be supplied by the central server upon initial account registration and setup. Data can then be cached on the server if the receiving host (applet) is not connected yet. 
     Data is sent to remote signed applet over its open HTTP connection. 
     Data is forwarded to receiving host over a local TCP/IP port. 
     First Embodiment 
     A first embodiment of a computer network communication system according to the present invention. More particularly, computer network communication system  300  will now be described with reference to  FIGS. 3 to 10 . System  300  includes: Internet  302 , virtual private network service provider (“VPNSP”) server  310 , institution A  320  and institution B  330 . 
     In  FIG. 3 , host A  322  desires to communicate, in a secure fashion, with host B  332 . Host B  332  is at a location remote from host B  332 . Both hosts are sitting on their own respective LAN&#39;s (institution A  320  and institution B  330 ) and are behind firewalls  326 ,  336  connected to the Internet. For illustration purposes, assume both firewalls  326 ,  336  have been configured to block all traffic except for initiated outgoing HTTPS (port  443 ). Thus, this example demonstrates how this technique can work in the most restrictive firewall settings. 
     Both LAN&#39;s  320 ,  330  also have PCs  324 ,  334  running a standard web browser  325 ,  335  with SSL (HTTPS) encryption. Both browsers also have access to the Internet via port  443   326   b ,  336   b , in order to browse secure Internet web sites. A user at institution A  320  logs into the VPNSP server  310  via an HTTPS (port  443 ) connection. By doing this, the user has announced his intention to communicate with Host B  332  and will be authenticated by the VPNSP server  310  as having the permission to communicate with Host B  332 . At this point, a Java applet will be downloaded into web browser A  325  that will be prepared to forward incoming traffic from web browser A  325  to Host B  332 . A user at institution B  330  will similarly download a Java applet into web browser B  335  and will be listening on some pre-defined port on institution A&#39;s LAN  320 . 
     Since host A  322  can connect via the predefined port directly to web browser A&#39;s IP address, host A  322  can commence to transmit data to web browser A&#39;s applet. The applet however is connected to the central VPNSP server  310  via the HTTPS connection and will thus commence to forward data to the VPNSP server. Assuming that Web browser B  335  has also made an HTTPS connection to the same VPNSP  310 , the data will be immediately forwarded to the applet running on web browser B  335  at institution B  330 , over its already open HTTPS connection. The Java applet running on web browser B  335  will then forward the data over institution B&#39;s LAN  330  directly to host B  332 . As far as host B  332  is concerned, web browser B  335  is considered to be host A  322 , and the reverse is true for host A  322  and web browser A  325  (i.e., host A thinks that web browser A is host B). 
     Note that both web browser A  325  and web browser B  335  preferably have live HTTPS connections to VPNSP server  310  simultaneously for this to work. An alternative is a “delayed transfer” or “store and forward” approach where web browser A  325  is connected to VPNSP server  310  and web browser B  335  is not. Host A  322  could still transmit data via web browser A  325  from where it will be temporarily cached at VPNSP server  310 . As far as host A  322  is concerned, the data has been successfully transmitted. As soon as web browser B  335  connects to VPNSP server  310 , the cached data will now be transmitted on to host B  332  and removed from the VPNSP server. This delayed transfer model can be implemented by an additional upper layer protocol implementation on the VPNSP server. Another (less preferred alternative) is to write the VPNSP code so that communications pass directly between the browsers without going through intermediate server  310 . 
     In the above example, either host A  322  or host B  332  could be a user on his home PC directly connected via their respective Internet service provider (“ISP”) to the Internet. Also, the applet player may actually reside on the sending or receiving host. 
     Now, communication methodology will be discussed. The standard HTTP model used by web browsers only allows client to server requests under a solicited-data-only type connection. In standard HTTP systems, a web server typically cannot initiate communication to a web browser. The system  300  embodiment of the present invention has bi-directional communication between the browsers and the server. In order to achieve this, a bi-directional model is implemented where the client does initiate all requests. 
     A preferred method for initially establishing an unsolicited data connection will now be discussed with reference to  FIGS. 4 to 7 .  FIGS. 4 and 5  illustrate how the remote server initiates sending data to a client. At  FIG. 4 , an applet  350  initiates connection with an HTTP GET request to remote VPNSP server  310 . If no data destined for the client is immediately available, the server may keep the connection open by not replying to the GET immediately. If a timeout occurs or the connection closes for any unknown reason, the client immediately issues another GET request to the server. Note that the idle state of this model is an open GET request to which no response has yet been made. 
       FIG. 5  shows how the server sends data to applet  350 . Note that the server can send data to the client at any time (in response to an open GET request).  FIGS. 6 and 7  illustrate how a client initiates sending data to the remote server. At  FIG. 6 , applet  350  issues a standard HTTP POST request. At  FIG. 7 , applet  350  sends data as part of the normal POST transmission. This transaction terminates normally after the data is sent. Note that the client can send data to server at any time (by issuing a new HTTP POST request). Although in reality the client initiates all communications, this model effectively simulates full bidirectional socket functionality, and thereby provides a type of unsolicited-input connection because the client listens for data from VPNSP server  310 . 
     Second Embodiment 
     Now, upper layer protocol and proxy services will be discussed with reference to  FIG. 8 . In addition to the secure tunneling described thus far, upper layer proxy services can be included in the VPNSP server to provide complete turnkey solutions for secure Internet transmission of a specific network protocol. The following section will describe one example of an implementation of this concept. In particular, a DICOM proxy service will be described which enables secure transmission of medical images. As pointed out before, this proxy service is supplied via machine independent applets from a centralized server. 
     This approach completely solves the deployment problem of installing software on both ends (standard approach). Since the applets on each end can communicate upstream to the central server through the firewall, they thus have the ability to proxy local traffic over these same existing open, unsolicited-input connections. 
     A computer network communication system  400  according to the present invention, involving DICOM Proxy Service, will now be explained with reference to  FIG. 8 . Host A is present in the form of a medical image device CT scanner  422  and Host B is present in the form of remote viewing station  436  at a remote diagnostic center. Despite the lack of an expensive private communication line connecting these remote locations, system  400  allows private and sensitive medical images to be sent between remote locations (across town or even across the world). 
     In system  400 , CT scanner  422 , at a first hospital, communicates directly with a diagnostic workstation (“WS”)  436 , located at a different hospital, using the DICOM protocol and the DICOM proxy applets. For illustration purposes we will assume that the DICOM traffic on both LAN&#39;s  420 ,  430  is affected using the DICOM standard TCP/IP port  104 . Alternatively, any port could be used. 
     In  FIG. 8 , CT scanner  422  has its own application title of CTAE. For it to transmit (push) patient images to the Diagnostic Workstation using DICOM protocol, it must have an Application Entity (AE) Title, TCP port number, and IP address for the remote workstation. Since there is no direct connection to the remote workstation, the CT is instead given a “fake” application title “ZMAE,” the IP address of the browser, and in this case, port  104 . The first step is that the user uses browser  424  to connect and login to DICOM Proxy Server  402 . Another user at the remote location will do the same with his browser  434 . At the remote site of LAN  430 , diagnostic workstation  436  has been configured to receive images from the “fake” application title “ZMAE” on its end along with the IP address of browser  434  and the port (again  104  in this example). 
     When all the connections are in place, CT scanner  422  makes a DICOM association with ZMAE. The applet running on browser  424  simply forwards the DICOM association via HTTPS as in the generic VPNSP case to DICOM proxy server  402 . Here DICOM proxy server  402  accepts the association and effectively fools CT scanner  422  into thinking it is talking to a real DICOM destination (DWAE). DICOM proxy server  402  does the real work of taking the incoming DICOM packets and stripping the “fake” destination (in this case ZMAE) and replacing it with the real destination AET (DWAE). DICOM Proxy Server  420  preferably knows the true destination, as this was setup when the account was initially created. 
     In summary, two methodologies are implemented to allow the above example to work. The first methodology is the tunneling of the DICOM traffic through existing web HTTP connections created by the browsers and forwarded locally by the signed applets running within the two respective browsers. This is different from the conventional approach because the proxy software itself is deployed by a machine and OS independent applet. The second methodology is the actual high level proxying of the DICOM protocol itself by the DICOM Proxy Server. This implementation of the DICOM protocol allows each local host to think it is connecting to another local host when in fact the actual data is being tunneled through the public Internet and securely encrypted. In combination, these two techniques work especially well in combination for connecting an internet protocol between two remote locations over a secured public line in a hardware and OS independent fashion and without the permanent installation of any additional hardware or software at either the transmitting or receiving end. 
     Third Embodiment 
       FIG. 9  shows a third embodiment of a computer network communication system  500  according to the present invention. System  500  includes WAN  502 , client A computer  510 , client B computer  520  and server computer  530 . WAN  502  is any wide area network that is now known or developed in the future. Generally, WAN will be a public network such that access to the communication links of WAN are substantially unrestricted and members of the general public are permitted to make communications over WAN  502 . 
     Client A computer includes VPN/proxy software  512  and browser software  514 . Because of its VPN aspect, VPN/proxy software  512  is software that can be used to set up a virtual private connection between client A computer and one or more predetermined computers present on WAN  502  (e.g., client B computer). Because of its proxying aspect, VPN/proxy software  512  can additionally be used to proxy communications VPN communications to be transmitted over WAN  502 , where the VPN communications originate on other computers (not shown) connected to client A computer  510  by a LAN (not shown, e.g., a DICOM network in a hospital). 
     Browser software  514  can also be used to communicate data to and from client A computer  510  over WAN  502 . However, the browser is preferably a standard browser and does not have functionality to handle VPN type communications. This generally means that the communications effected by browser  514  will be less secure than the VPN communications made using VPN/proxy software  510 . 
     Despite this limitation, browser software  514  is instrumental in the exemplary VPN communications of the present embodiment both because it helps get the VPN/proxy software downloaded to client A computer  510  in the first place, and further because encryption module  514   a , which is a part of the browser software, can be used to encrypt and decrypt VPN communications. This downloading and this encryption/decryption operation will be further explained below in connection with a flowchart. Also, other data communication functionality of the browser software  514  may be exploited to assist VPN/proxy software  512  in making its VPN type data communications. 
     Client B computer  520  is located at a remote location with respect to client A computer  510 . VPN/proxy software  522  and browser software  524  are comparable to the corresponding pieces of software discussed above in connection with the client A computer. 
     Server computer  530  is a constructed with hardware and equipped with software as a server computer capable of receiving unsolicited requests for data to be served. Server computer  530  includes VPN/proxy server software  532 , VPN/proxy server software memory  534 , VPN way station software  536  and VPN data communication store and hold memory  538 . While  FIG. 9  shows only a single server computer for purposes of clarity of illustration, preferable multiple servers (e.g., server farms) are used to provide redundancy, power to handle more traffic and enhanced reliability. 
     VPN/proxy server software  532  is software that handles various requests, received over WAN  502 , to download the VPN/proxy software  512 ,  522 . In accordance with its programming, VPN/proxy software will evaluate which requests to download the software should be honored. For example, the party that controls server computer  530  may determine that download requests only from authorized clients are to be honored. Assuming that a valid download request is received, VPN proxy server software  532  will cause the VPN/proxy software  512 ,  522  to be read from VPN/proxy server software memory and then downloaded to the requesting computer over WAN  502 . 
     VPN way station  536  is used to effect VPN type communications between client computers that are equipped with the VPN/proxy software  512 ,  522 , such as client A computer  510  and client B computer  520 . As will be further explained below in connection with a flow chart, VPN way station software receives VPN type data communications that are en route over WAN  502 . 
     In some embodiments of the present invention, the VPN way station software allows the communications to be communicated when firewalls are in the way. At many client computers, the computer can communicate by opening a connection in some predetermined port in a client computer system&#39;s firewall. Because of the restrictions on the type of connections that may be established, it may be difficult for VPN client computers to directly communicate with each other over a mutual unsolicited-input connection. In this case, the VPN way station software  536 , in conjunction with a source client computer and a destination client computer, can establish a separate unsolicited-input connection with each client computer, as shown in  FIG. 9 . 
     Also, VPN way station software  536  may be used to temporarily store data communications in VPN data store and hold memory  538 . This is useful, for example, when the intended recipient of a VPN data communication is not ready to receive such a communication when it is sent. When the destination computer becomes ready to receive the data communication, VPN way station software can cause the communication to be read from the VPN data communication store and hold memory and sent to the (now-ready) destination computer. Additionally, the VPN way station software and the VPN data communication store and hold memory can be used to perform centralized archiving of data communications (e.g., medical images). 
     Finally, in some embodiments, the record of VPN communications maintained by the VPN way station software may provide a basis so that the provider of the VPN/proxy software and related server computer services can be compensated (in whole or in part) by various clients on the basis of the number and/or volume of VPN communications actually transmitted over system  500 . 
     Now exemplary data communication over system  500  will be discussed with reference to the flow chart shown in  FIG. 10 . As shown in  FIG. 10 , processing starts at step S 1 , wherein, client A computer  510  and client B computer  520  each request VPN/proxy server software  532  to cause downloading of the VPN/proxy software from VPN/proxy server software memory  534  to the respective computers  510 ,  520 . It is noted that the VPN/proxy software is preferably does not permanently reside on any client computer, but rather, this software is downloaded to clients on an as-needed basis. This is preferred because the VPN/proxy software is subject to revision and debugging. Specifically, if the “master” version of the software is stored, updated and maintained on the server computer  530 , then the downloaded software will automatically incorporate all the latest changes, each time it is downloaded. 
     Alternatively, the VPN/proxy software may reside on various clients, but the various clients may be allowed or mandated to replace their resident VPN/proxy software when there has been (or might have been) a change in the “master version” stored at the server computer. By not requiring a fresh download each and every time a series of communications is to be made, download time and download bandwidth may be conserved, while still ensuring that the most up-to-date version of the software is in use. For example, the software may contain revision codes that allow a client and server computer to efficiently determine whether a VPN/proxy program that is resident on a client is truly the most up-to-date version. 
     In step S 1 , it is the browser software  514 ,  524  that requests and effects the VPN/proxy software transfer from server computer  530 . Because the server computer is a server, it can receive and respond, as appropriate, to these unsolicited requests for downloads received over WAN  502 . 
     Once the VPN/proxy software  512 ,  522  is downloaded to the respective computers  510 ,  520 , processing proceeds to step S 2 , wherein the freshly-downloaded VPN/proxy software  512  of client A computer  510  (with support as necessary from browser software  514 ) establishes an unsolicited-input connection with VPN way station software  536  of server computer  530 . Although client A computer  510  must initiate this unsolicited-input connection with the server computer, once it has been opened, the connection can be maintained open so that client A computer can listen for data communications from server computer  530  over WAN  502  on an ongoing basis, without specifically requesting data from server computer  530  on a communication-by-communication basis. For example, by issuing GET commands on an open thread (as explained in connection with  FIGS. 4 to 10 ) can be used to facilitate this unsolicited-input connection. In  FIG. 9 , this unsolicited-input communication is represented by the line drawn from VPN/proxy software  512  to the VPN way station software  536 . 
     Processing proceeds to step S 3 , wherein VPN/proxy software  522  sets up a similar unsolicited-input connection between client B computer and server computer  530 . While it is preferred to establish unsolicited-input connections between the source computer (that is, client A computer  510 ) and the server computer, and further to establish an unsolicited-input connection between the destination computer (that is, client B computer  520 ), this may not be necessary for all embodiments. More particularly, each separate communication necessary to effect the ultimate VPN data transfer could be initiated by the respective client computers, under solicited-data-only type connections. However, this alternative method may be less efficient because each client computer would need to be provided with the software and logic necessary initiate requests to the server computer on a communication-by-communication basis. 
     Processing proceeds to step S 4 , wherein VPN/proxy software  512  receives a data communication from a source computer (not shown) over a LAN (not shown). The proxy functionality of VPN/proxy software  512  allows this communication (not ultimately destined for client A computer  510 ) to be received by client A computer as a proxy. Also at step S 4 , VPN/proxy software  512  restructures the data communication, as necessary, so that it is in appropriate form and format for sending as a secure, VPN communication over WAN  502 . Generally speaking, this restructuring can be considered as a protocol change (e.g., wrapping the data communication in a higher level protocol(s) to facilitate transmission over WAN  502 ). 
     Also at step S 4 , the data communication is encrypted by using SSL encryption software, which is part of encryption module  514   a  of client A computer  510 . Use of this SSL encryption, which is conventionally included in browser software, is advantageous because most computers will be preloaded with a browser with SSL encryption, so there is no need to encode the encryption functionality into the (regularly downloaded) VPN/proxy software. Alternatively, the VPN/proxy software could be provided with its own encryption scheme. 
     At step S 5 , the VPN data communication is sent over the unsolicited-input connection, established at step S 2 , from client A computer  510  to the VPN way station software  536  of server computer  530 . 
     At step S 6 , VPN way station software  536  forwards the VPN data communication over the unsolicited-input connection, established at step S 3 , from server computer  530  to client B computer  520 . At step S 6 , the VPN data communication, and/or ancillary information regarding the specific VPN data communication, can be stored in store and hold memory  538 . By using the store and hold memory, the VPN communication can be saved for a relatively long period of time, in the event that there is difficulty in immediately relaying the VPN data communication to client B computer  520  (e.g., client B computer is down or unavailable). 
     It is noted that the proxy functionality of VPN/proxy software  522  can allow client B computer to receive the VPN data communication on behalf of another computer (not shown) that is connected to client B computer by means of a LAN (not shown). Once the VPN data communication reaches VPN/proxy software  522  of client B computer  520 , processing proceeds to step S 7 . 
     At step S 7 , the VPN data communication is restructured so that it can be utilized at client B computer  520  or at some other computer that is connected to the client B computer by means of a LAN. One part of this restructuring may involve a protocol change, such as stripping away high level protocol(s) that were temporarily necessary to allow the VPN data communication to be communicated over WAN  502 . Also, the VPN data communication is decrypted using encryption module  524   a  of browser software  524 . According to the foregoing method, the VPN communication was effected, despite the fact that no VPN software is permanently resident on either the client A source computer or the client B destination computer. 
     Fourth Embodiment 
     As shown in  FIG. 11 , computer network communication system  600  according to the present invention is similar in most respects to previously-discussed system  500 , and, therefore, system  600  is not discussed in great detail herein. Like system  500 , system  600  includes VPN/proxy server software so that the VPN/proxy software can be downloaded to a client machine upon demand. However, it is noted that in system  600 , unlike system  500 , does not include VPN way station software  536 . According, VPN communications are communicated from VPN/proxy software  612  to VPN/proxy software  622  over WAN  602 , without any sort of intermediate way station. (See communication line connecting software  612  to software  622  in  FIG. 11 .) Currently, this embodiment is not preferred because it is difficult to establish unsolicited-input connections between two non-server computers. 
     Fifth Embodiment 
       FIG. 12  shows another embodiment of a computer network communication system  700  according to the present invention. Communication system  700  includes WAN  702 , client A computer  710 , client B computer  720  and VPNSP e-mail forwarding system  730 , including a VPNSP server and a local SMTP server. Once again, WAN  702  is any wide area network that is now known or developed in the future. Generally, WAN  702  will be a public network such that access to the communication links of WAN  702  are substantially unrestricted and members of the general public are permitted to make communications over WAN  702 . 
     Like previous embodiments, Client A computer  710  includes VPN/proxy software  712  and browser software  714 . The VPN/proxy software  712  can be used to set up a virtual private connection between client A computer  710  and one or more predetermined computers present on WAN  702  (e.g., client B computer  720 ). Because of its proxying aspect, VPN/proxy software  712  can additionally be used to proxy VPN communications to be transmitted over WAN  702 , where the VPN communications originate on other computers (not shown) connected to client A computer  710  by a LAN. 
     Client A computer  710  further includes a client e-mail application  718 , which uses a transfer protocol to send and receive e-mail messages. E-mail application  718  may a typical client e-mail application such as Netscape Communicator, Outlook Express and Eudora, all of which use a Simple Mail Transfer Protocol (SMTP). As would be understood by one of ordinary skill in the art, other e-mail applications using alternative transfer protocols may be used without departing from the scope of the present invention. 
     Client B computer  720  is located at a remote location with respect to client A computer  710 . In some exemplary embodiments, VPN/proxy software  722 , browser software  724  and client e-mail application  748  are comparable to the corresponding pieces of software discussed above in connection with the client A computer  710 . 
     VPNSP e-mail forwarding system  730  includes server computer  728  having VPN/proxy server software  732  and VPN/proxy server software memory  734 . While  FIG. 12  shows only a single server computer for purposes of clarity of illustration, preferably multiple servers (e.g., server farms) are used to provide redundancy, power to handle more traffic and enhanced reliability. 
     VPN/proxy server software  732  is software that handles various requests, received over WAN  702 , to download the VPN/proxy software  712 ,  722 . In accordance with its programming, VPN/proxy software  712 ,  722  will evaluate which requests to download the software should be honored. For example, the party that controls server computer  730  may determine that download requests only from authorized clients are to be honored. Assuming that a valid download request is received, VPN proxy server software  732  will cause the VPN/proxy software  712 ,  722  to be read from VPN/proxy server software memory  734  and then downloaded to the requesting computer over WAN  702 . 
     According to some preferred embodiments, the VPN/proxy software  712 ,  722  is an applet that is loaded into the browser (or applet runner) after the user has logged onto the VPNSP server  728  so that there is no need for permanent resident client-based VPN/proxy software. Also, a proxy is not necessarily created all the way through to client B computer  720 . Instead, the only connection is to local SMTP server  744 , which may reside on the same computer system or LAN as VPNSP server  728 . Client B may or may not use their own VPNSP to retrieve their e-mail, but would typically use a protocol other than SMTP (such as POP or IMAP) since SMTP is usually used for sending e-mail instead of retrieving it. 
     VPNSP e-mail forwarding system  730  further includes local SMTP server  744 , which is designed to transmit and store e-mail messages. SMTP server  744  includes e-mail forwarding software  750  and e-mail storage memory  754 . While  FIG. 12  shows only a single server computer for purposes of clarity of illustration, preferably multiple servers (e.g., server farms) are used to provide redundancy, power to handle more traffic and enhanced reliability. 
     In some exemplary embodiments, browser software  714  does not function as the integral e-mail communicator. Instead, client e-mail application  718  is used to communicate e-mail messages from client A computer  710  over WAN  702 . Client e-mail application  718  pushes the e-mail message via SMTP directly to the VPN/proxy software  712  over a local host connection (such as IP address  127 . 0 . 0 . 1  on port number  25 , the default SMTP port). 
     Browser software  714  helps get the VPN/proxy software downloaded to client A computer  710  and encryption module  714   a,  which is a part of the browser software, can be used to encrypt and decrypt VPN communications. The VPN communications are encrypted by using SSL encryption software, which is part of encryption module  714   a  of client A computer  710 . 
     In the present embodiment, the VPN communications are e-mail messages that are transmitted as SMTP. These e-mail messages are encrypted and encapsulated into the VPNSP format and transmitted over an existing https connection through WAN  702  directly into the VPNSP server  728  of the VPNSP forwarding system  730 . The VPNSP server  728  utilizes SSL decryption software to convert these e-mail messages back into SMTP and the local SMTP server  744  forwards the e-mail message to an SMTP server  760  having a POP/IMAP server  764  and an e-mail storage memory  768 . At this point, client B can use client e-mail application  748  to retrieve the e-mail message from POP/IMAP server  764 . In other exemplary embodiments, SMTP server  760  may be followed by a series of further SMTP servers depending on how the e-mail message is addressed. Alternatively, local SMTP server  744  may include its own POP/IMAP server  772  so that client B may retrieve e-mail messages directly from local SMTP server  744 . 
     Some of the Inventive Ideas Present in the Foregoing Embodiments 
     Various embodiments of the invention have now been discussed in detail. Now the opportunity will be taken to discuss some of the potentially inventive concepts embodied in the foregoing embodiments. 
     One important concept is the idea that router software, VPN software, VPNSP software and other similar types of software maybe downloaded over a computer network. The simplest types of routers do not change the content or the protocol of the routed data communications at all. More complicated routers (as well as VPN and VPNSP systems) may change the protocol of data communications. 
     Conventionally, there are seven layers of protocol (according to the OSI—Open Systems Interconnect model: Application, Presentation, Session, Transport, Network, Data Link, Physical with Physical being the “lowest”). Changes, by various router, VPN and VPNSP systems, are especially common at the application layer and above. The types of protocol changes that may be made can reflect things such as machine id (MAC address), encryption scheme, port numbers, originating IP address and higher lever information (e.g., application title). For example, preferred VPNSP systems may modify port data or encryption scheme in order to better abide by network rules set up by network administrators (e.g., hospital network administrators). 
     VPN software establishes a direct, encrypted, virtual private network type connection. The encryption is what makes the VPN communication private. The VPN connection is not necessarily direct in the sense that the communication travels from source (e.g., source LAN) to destination (e.g., destination LAN) over a single unbroken wire, or over a single wireless link. Rather the VPN communication is merely as direct as a non-VPN communication made over a similar network would be. For example, a typical Internet communication may actually follow a convoluted path over a multiplicity of networked telephone lines and associated routers. A VPN communication made over the Internet would only be expected to be direct in the way that the conventional Internet communication is direct. 
     VPNSP software establishes an indirect, encrypted, virtual private network type connection. In many embodiments of the present invention, the VPNSP software connection is also indirect because network communications, instead of passing directly from a source to a destination, must pass through a site maintained by the service provider. The provider&#39;s site may be a predetermined site, or one of a set of predetermined sites working in concert. Sometimes the protocol of the communication will be modified at the provider&#39;s site. 
     Often VPN and VPNSP systems will include an entire encryption scheme in the VPN or VPNSP software itself. However, according to the present invention, VPN or VPNSP encryption may rely on preexisting encryption schemes already present in various software that is commonly resident on computers. For example, much Internet browser software has built-in encryption capabilities. According to the present invention, VPN or VPNSP software of the present invention may look to built in software encryption capabilities, rather than writing these into the main body of the VPN or VPNSP code. 
     For example, under preferred embodiments of the present invention, wherein VPN and/or VPNSP code is downloadable from a central location, it is advantageous to utilize (fairly ubiquitous) encryption software already built into network browsers—this saves on the amount of VPN or VPNSP code that must be transferred during the periodic downloads. 
     The preferred data structure for transferring router, VPN and/or VPNSP code according to the present invention is an applet that is executed by an applet runner. In the future downloadable computer programs may, of course, take different forma or be called by different names. 
     CONCLUSION  
     Many variations on the above-described computer network communication system are possible. Such variations are not to be regarded as a departure from the spirit and scope of the invention, but rather as subject matter intended to be encompassed within the scope of the following claims, to the fullest extent allowed by applicable law.