Abstract:
The gaming network described herein includes network security features, host security features, audit protocols, and design architecture approaches to reduce the possibility of network attacks. The gaming network provides for traffic confidentiality, encryption, message authentication, secure authentication mechanisms, anti-replay protection of traffic, key management mechanisms, robust network availability, misrouting and redirection protection and prevention, rejection of external traffic, and a high entry-barrier to device addition to the network. The host protection and security includes secure host initialization, disabling unneeded components, download verification, disabling of unused IP ports, discarding traffic, strong passwords, dynamic one-time passwords for remote login, disabling default accounts, and appropriate “least-level” device privileges. Audit requirements include integrity protection of audit logs, appropriate definition of auditable events, auditing of anomalous behavior, chain of evidence preservation, shutdown if audit disabled, full log entry audit, personal ID and time access audit trail, and auditing of internal user actions.

Description:
COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     The claimed invention relates generally to a network, and more particularly, to a gaming network. 
     In early gaming environments, gaming machines were stand-alone devices. Security of the gaming machines was accomplished via physical locks, security protocols, security personnel, physical and video monitoring, and the need to be physically present at a machine to attempt to breach the security of the gaming machine. By the same token, management of the gaming machines required a great deal of personal physical interaction with each gaming machine. The ability to change parameters of the gaming machine also required physical interaction. 
     In view of the increased processing power and availability of computing devices, gaming machines have become customizable via electronic communications and remotely controllable. Manufacturers of gaming equipment have taken advantage of the increased functionality of gaming machines by adding additional features to gaming machines, thereby maintaining a player&#39;s attention to the gaming machines for longer periods of time increasing minimum bet and bet frequency and speed of play. This, in turn, leads to the player wagering at the gaming machine for longer periods of time, with more money at a faster pace, thereby increasing owner profits. 
     One technique that has been employed to maintain a player&#39;s attention at the gaming machine has been to provide players with access to gambling-related information. In this regard, attaching a small electronic display to the gaming device, gambling-related information, as well as news and advertisements can be sent to the player. The gambling-related information may include, for example, information on sports betting and betting options for those sporting events. Additionally, the gambling-related information may also include information such as horse racing and off-track betting. News and advertisements can also maintain a player&#39;s attention by providing the player with access to information ranging from show times, to restaurant and hotel specials, and to world events, thus reducing the need and/or desire of the player to leave the gaming machine. 
     Moreover, it has been shown to be desirable to provide the player with interactive access to the above information. This type of interactivity allows players significantly more flexibility to make use of the above-described information. The gambling-related information can also be utilized by the player in a much more efficient manner. In this regard, greater levels of flexibility and access are likely to make the player remain and gamble at the gaming machine for significantly longer periods of time. 
     In addition, the player may participate in a “premium” promotion where the player is registered with the gaming establishment as a club member when the player inserts an ID card into the gaming machines during play. The player may be rewarded for certain play patterns (e.g. wager amounts, wager totals, payouts, time of play, or the like) and earn redeemable benefits or upgrade of club member status. 
     Attempts to distribute gambling-related information and advertisements to players and to allow the recognition of premium membership players have resulted in additional system components that may be attached to the gaming devices. These components for accessing and displaying information for gaming machines may include a keypad, card reader, and display equipment. 
     The amount of interactivity and data presentation/collection possible with current processor based gaming machines has led to a desire to connect gaming machines in a gaming network. Current networks for gaming machines have been primarily one-way in communication, have been slow, and have been proprietary (custom designed and incompatible with commercial networking equipment). Prior art networks provided accounting, security, and player related data reporting from the gaming machine to a backend server. Secondary auditing procedures allowed regulators and managers to double check network reporting, providing a method of detecting malfeasance and network attacks. However, such security is remote in time from when a network attack has occurred. Prior art networks lack many security features needed for more rapid detection of cheating from a variety of possible attackers. 
     Although prior art networks of gaming machines provide advantages to gaming establishment operators, they also engender new risks to security of the gaming establishment and to the gaming machines. Not only is traditional data associated with gaming machines now potentially at risk on the gaming network, but personal player information is now at risk, as well. 
     In addition, the proprietary nature of prior art gaming machine networks limits the ability to use commercially available technology, This adds to the cost of gaming networks and limits their scalability and the ability to upgrade as technology improves. Further, as gaming machines are grouped in networks, the value of the pooled financial data traversing the network creates a great temptation to attack the network. The potential reward from attacking a network of gaming machines is greater than the reward from attacking a single machine. 
     Attempts to illicitly obtain access to the gaming network are referred to as network attacks. These attacks can be driven by different motivations and are characterized by the type of attack involved. In addition, attackers can be either insiders (gaming establishment employees, regulators, security personnel) or outsiders.  FIG. 7  illustrates possible attacks on a network. The gaming network  701  may be attacked by an insider  703 . Insiders include casino employees, regulators, game manufacturers, game designers, network administrators, etc. Outsiders  704  might also attack the network  701 . Outsiders may include hackers with an IP connection attacking the network and/or devices (including games) on the network. The network may be attacked via a bridge  702  to the Internet. Examples of attacks are described below. 
     Attack Motivation 
     Typical motivations for attack on a gaming network include the desire to steal money or to embarrass or blackmail an entity. For example, an attacker may attempt to steal money from the gaming establishment, from a patron or player, or from a regulatory or other political body (e.g., a state that taxes gaming revenue). The attempt to steal may involve attempts to artificially manipulate wagers or payouts to the attacker&#39;s benefit. An attacker may also attempt to obtain credit or other personal information from the network that can be used to illicitly obtain money. Other attackers (typically insiders) may wish to manipulate accounting data to defraud government agencies by underreporting taxable revenue. An attacker may attempt to collect gaming habit or other sensitive information regarding a patron as a blackmail threat, or the attacker may attempt to embarrass or blackmail the gaming establishment, the gaming machine manufacturer, a regulating agency, or a political organization by showing the vulnerability of the network to attack. Instead of taking money directly, an attacker may attempt to manipulate a network so that a gaming establishment loses money to players. 
     Attack Types 
     Attackers may attempt one or more direct attacks against the network, attacks against hosts, physical attacks, or other types of attacks. Attacks against the network may include attempts to obtain plaintext network traffic, forging network traffic, and denying network services. 
     Consequently, there are a number of methods of attack to obtain plaintext traffic. An attacker may eavesdrop (e.g., electronically) on unprotected traffic. The plaintext messages may be openly accessed or inferred via message and traffic analysis. Eavesdropping may be accomplished by illicitly controlling a device that is a legitimate part of the network or by re-routing network traffic to the attacker&#39;s own device. 
     Furthermore, if the attacker has access to the network and can mimic network protocols, the attacker may forge network traffic so that malicious messages are routed as legitimate messages. Such malicious messages can affect game play, send false financial transactions, reconfigure network administration, and/or disable security features to permit other forms of attack, or to hide current attacks. This type of attack may also include repeating legitimate messages for malicious purposes, such as repeating a password message to gain access to the privileges associated with that password, playing back a cash withdrawal request, a winning game play message, or a jackpot won event. 
     Still further, “denial of service” attacks are a notorious method of attacking a network or server. Such attacks often consist of flooding the network with bogus messages, therefore blocking, delaying, or redirecting traffic. The saturation of the network at the devices, servers, IP ports, or the like, can prevent normal operation of the network, especially for those network services that are time sensitive. 
     Moreover, an attacker may also use the network to attack a host or to attack the host directly via a local console. This is accomplished by attacking vulnerable, exposed, and/or unprotected IP ports, or via a “worm” transmitted via email, for example. In this way, malicious code can be introduced into the network to open the door for later attacks and to mask this and other attacks. 
     In addition, physical attacks on the network devices may also be a goal of an attacker. The devices, hosts, servers, and consoles should all have physical protection and security to prevent access by outsiders or by unauthorized insiders. Devices requiring such protection may include game machines, network cables, routers, switches, game servers, accounting servers, and network security components including firewalls and intrusion detection systems. 
     Other attacks may include attacks on the encryption/certification system. An attacker may attempt to compromise or to obtain the private key (e.g. of an operator or a manufacturer) of a public key infrastructure. Alternatively, the attacker may compromise the certifying authority of the network owner. Other schemes may include reinstalling older, but legitimate versions of software (recognized by the system as legitimate) the older version not being updated for corrected security flaws. Bridging a secure network to another network may also be attempted. 
     In some cases, the regulatory jurisdiction may have its own encryption key. This may be another type of inside attack that may be made. Someone in the regulatory jurisdiction may attempt to move or spoof data on the network for one or more of the purposes described above. 
     Accordingly, a gaming network requires robust protection against attacks from insiders and outsiders using a variety of attack methods. 
     SUMMARY OF THE INVENTION 
     Briefly, and in general terms, the gaming network described herein includes network security features, host security features, audit protocols, and design architecture approaches to reduce the possibility and success of network attacks. More particularly, the gaming network provides for traffic confidentiality, encryption, message authentication, secure authentication mechanisms, anti-replay protection of traffic, key management mechanisms, robust network availability, misrouting and redirection protection and prevention, rejection of external traffic, and a high entry barrier to device addition to the network. 
     The host protection and security aspects include secure host initialization, disabling unneeded components, download verification, disabling of unused IP ports, discarding traffic, strong passwords, dynamic one time passwords for remote login, disabling default accounts, and appropriate “least-level” device privileges. 
     Audit requirements include integrity protection of audit logs, appropriate definition of auditable events, auditing of anomalous behavior, chain of evidence preservation, shutdown if audit disabled, full log entry audits, personal ID and time access audit trails, and auditing of internal user actions. 
     In one embodiment of the gaming network, a host and a network device authenticate themselves to each other on the gaming network and generate a first security association. The host and the network device, which may be a gaming machine, use the first security association to generate a second security association for use in protecting message traffic on the gaming network. Each message has a certain minimum level of protection, provided by encryption in one embodiment, while still permitting additional security measures to be implemented in transactions between devices on the gaming network. In another embodiment, the negotiation used to authenticate a device to a host is the Internet Key Exchange (IKE) protocol phase I. In yet another embodiment, the protection of message traffic on the gaming network is accomplished by IKE protocol phase II. 
     In another embodiment, the gaming network comprises a core layer with a host server and switches, a distribution layer with managed routers and switches, and an access layer that includes managed switches and game machines. In another embodiment, the gaming network includes intrusion detectors to monitor attempts to attack the network. In yet another embodiment, the gaming network includes automatic disabling of any device where an intrusion attempt is detected by the intrusion detector. Similarly, in yet another embodiment, the gaming establishment system maps the association of legitimate IP addresses with device MAC addresses, unique device ID&#39;s (DID) and treats any alteration of any IP/MAC/DID association as an intrusion attempt. In still another embodiment, the gaming network uses private network IP addresses for network members. In another embodiment, the gaming network implements a virtual private network protocol. 
     These and other features and advantages of the claimed invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an embodiment of functional layers of a gaming network. 
         FIG. 2  is a block diagram of an embodiment of a gaming network. 
         FIG. 3  is a flow diagram of initialization of a network device in an embodiment of a gaming network. 
         FIG. 4  is a flow diagram of traffic authentication in an embodiment of a gaming network. 
         FIG. 5  is a flow diagram of an attack detection protocol in an embodiment of a gaming network. 
         FIG. 6  is a flow diagram illustrating a network device initialization sequence in an embodiment of the gaming network. 
         FIG. 7  is a block diagram illustrating examples of possible network attacks. 
     
    
    
     DETAILED DESCRIPTION 
     The claimed invention is directed to a gaming network. The preferred embodiments of the system and method are illustrated and described herein, by way of example only, and not by way of limitation. 
     The gaming network described herein proposes an architecture and system that provides an appropriate level of security from network attack. There exist techniques to authenticate and verify individual messages or activities in existing gaming establishment networks relying on proprietary protocols, transport and message formats. However, the gaming network described herein provides additional protection to the network itself particularly when use of commercially based IP equipment is envisioned, above and beyond particular security protocols, for activities and transactions carried on the network. The gaming network is independent of, and in addition to, security techniques for particular transactions or activities. 
     Referring now to the drawings, wherein like reference numerals denote like or corresponding parts throughout the drawings and, more particularly to  FIGS. 1-7 , there is shown one embodiment of the gaming network constructed in accordance with the claimed invention. As shown in  FIG. 1 , the network includes a core layer  101  over a distribution layer  102  above an access layer  103 . The core layer  101  serves as a gateway between servers and the gaming devices. The core layer  101  is contemplated to be a so-called “back end” layer that resides in an administrative location, separate from the gaming floor, for example, and protected physically and electronically. 
     The distribution layer  102  serves to collect traffic between the core layer  101  and the access layer  103 . The distribution layer may comprise trunks and switches that route message and signal traffic through the network. The access layer  103  provides a physical interface between the gaming machines (and any of their associated devices) and the rest of the network. This is done via managed switches. 
     One embodiment of a network using the layered scheme of  FIG. 1  is illustrated in  FIG. 2 . The core layer  101  includes one or more servers  201  that are coupled via a communication path  202  to one or more switches  203 . In one embodiment, the servers and switches of the core layer  101  are located within the gaming establishment premises in a secure administrative area. The servers  201  may, but are not required to be, game servers. The communication path  202  may be hardwire (e.g., copper), fiber, wireless, microwave, or any other suitable communication path that may be protected from attack. In one embodiment, the switches  203  are L2/L3 switches. However, one of ordinary skill in the art will appreciate that other types of switches may be used without departing from the scope or spirit of the claimed invention. 
     The distribution layer  102  communicates with the core layer  101  via high bandwidth communications links  204 . These links may be copper, fiber, or any other suitable link. If desired, redundant links  205  may be built into the system to provide more failsafe operation. The communications links couple the core layer switches  203  to the distribution layer switches  206 . These may be one or more switches, such as L2 switches, for example. 
     The distribution layer  102  communicates with the access layer  103  via a high capacity communication link  207 . The link  207  may be wire, fiber, wireless, or any other suitable communication link. In the embodiment of  FIG. 2 , the communication link  207  is coupled to a gaming carousel  208  that comprises a plurality of gaming machines (e.g., 16 gaming machines  215 A- 215 P). A managed switch  209  is coupled to the link  207  to provide an interface switch to a plurality of other managed switches  210  through  213 . In the embodiment illustrated, each of the managed switches  210 - 213  manages four game machines  215 ( x ). It is understood that the types of switches may be changed without departing from the scope of the claimed invention. Further, switches with more or fewer ports may be substituted and more or fewer tiers of switches in the access layer may be used, as well, without departing from the scope or spirit of the claimed invention. In another embodiment, each game machine has its own managed switch. 
     In one embodiment of the gaming network, the network uses TCP/IP sessions between the gaming machines  215  and the servers  201 . The TCP/IP sessions are used to exchange private information concerning game operations, game performance, network management, patron information, revised game code, accounting information, configuration and download, and other sensitive information. In one embodiment, sessions may be a single message and acknowledgement, or the sessions may be an extended interactive, multiple transaction session. Other instantiations may include UDP/IP, token ring, MQ, etc. 
     In one embodiment of the gaming network, intrusion detectors provide additional security. In this regard, there may be intrusion detectors located between each layer, such as intrusion detector  220  located between the core layer  101  and the distribution layer  102 , and the intrusion detector  221  located between the distribution layer  102  and the access layer  103 . In addition, certain sensitive locations or choke points may include intrusion detectors such as the intrusion detector  223  coupled to the switch  209 . The intrusion detector  223  may disable the individual ports of switch  209  to isolate attacks while permitting continued operation of the remainder of the gaming network. 
     Moreover, the gaming network may use a number of network services for administration and operation. Dynamic Host Configuration Protocol (DHCP) allows central management and assignment of IP addresses within the gaming network. The dynamic assignment of IP addresses is used in one embodiment instead of statically assigned IP addresses for each network component. A DNS (domain name service) is used to translate between the domain names and the IP addresses of network components and services. DNS servers are well known in the art and are used to resolve the domain names to IP addresses on the Internet. 
     Similarly, Network Time Protocol (NTP) is used to synchronize time references within the network components for security and audit activities. It is important to have a consistent and synchronized clock so that the order and the timing of transactions within the gaming network can be known with reliability and certainty. Network information can be gathered centrally at a single workstation by using the Remote Monitoring (RMON) protocol. SNMP (simple network management protocol) allows network management components to remotely manage hosts on the network, thus providing scalability. In one embodiment of the gaming network, SNMPv3 is used to take advantage of embedded security mechanisms to mitigate malicious attacks made against the configuration management function. Still further, TFTP (trivial file transfer protocol) is used by servers to boot or download code to network components. 
     In one embodiment, the network may be implemented using the IPv6 protocol designed by the IETF (Internet Engineering Task Force). When using IPv6, the network may take advantage of the Quality of Service (QoS) features available with IPv6. QoS refers to the ability of a network to provide a guaranteed level of service (i.e. transmission rate, loss rate, minimum bandwidth, packet delay, etc). QoS may be used as an additional security feature in that certain transactions may request a certain QoS as a rule or pursuant to some schedule. Any fraudulent traffic of that nature that does not request the appropriate QoS is considered an attack and appropriate quarantine and counter measures are taken. 
     Similarly, the Type of Service (ToS) capabilities of IPv4 may also be used in a similar manner to provide additional security cues for validation of transactions. Again, certain types of transactions may be associated with a particular specific ToS or a rotating schedule of ToS that is known by network monitors. 
     Traffic Content 
     In an embodiment of the gaming network, the traffic content varies in size and sensitivity. Messages may comprise transactional messages related to game play, such as coin-in. Other messages may be related to management, administration, or sensitive information, such as administrator passwords, new game code, pay tables, win rates, patron personal data, or the like. 
     Security 
     The gaming network includes network security features, host security features, audit protocols, and design architecture approaches to reduce the likelihood of success of network attacks. Where attacks cannot be prevented, the gaming network attempts to make such attacks expensive in terms of the computational power required, the time, risk, effect, and duration of the attack. Identification of attacks and the rapid recovery from such attacks should be emphasized, as should the limiting of the effect of any attacks. 
     Accordingly, the gaming network provides for traffic confidentiality. All nodes within the network exchange information that is confidentially protected. One method for providing confidentially protected data is by using encryption. A number of encryption schemes may be used, such as an FIPS approved encryption algorithm and an NIST specified encryption mode, such as the Advanced Encryption Standard (AES). 
     In addition, all nodes within the gaming network apply source authentication and integrity of all traffic. A suitable message authentication mechanism may be, for example, an FIPS approved algorithm such as the Keyed-Hash Message Authentication Code (HMAC) and SHA-1. All nodes automatically drop messages that have been replayed. As noted above, replayed messages are a means of attack on network security. 
     Key management mechanisms should be sufficient to resist attack. In one embodiment, a 1024 bit Diffie-Hellman key exchange with a 1024 bit DSA/RSA digital signature is used to render key attacks computationally infeasible. It should be noted that the key sizes are given as examples only. Smaller or greater key size can be used in the gaming network as security recommends. The gaming network should be robust, maintaining the availability of critical services. The network should include protection against misrouting and also discard any traffic that has a source or destination outside of the network. The gaming network should also require a minimum level of authentication and assurance before permitting an additional device on the network and prevent such connection when the assurance is not provided. 
     Host protection and security includes secure host initialization where the host performs a self-integrity check upon power-up initialization. All operating system components that are not needed are disabled. When software patches are downloaded to the gaming network, the host verifies them. The host checks for unused IP ports and disables them prior to connecting to the gaming establishment network. When processing network traffic, any traffic not addressed to the host is dropped from the processing stack as soon as possible. In the gaming network, all service, guest, and default administrator accounts that may be part of the operating system are disabled. In one embodiment, one-time passwords and/or multi-part passwords are used for remote login, if remote login is enabled. The one-time password may itself be a multi-part password. When using a multi-part password, different trusted individuals each hold a part of the multi-part password. The entire password is required for enablement of the system. This prevents any single individual from compromising security. Moreover, all host software components are operated with the lowest privilege necessary for sufficient operation. For example, software that can operate with “user” privilege will do so, to limit its usefulness to an attacker. 
     Audit requirements include integrity protection of audit logs from date of creation and throughout their use. Events that are audited in an embodiment of the gaming network include account logon events (both success and failure), account management (both success and failure), directory service events (failure), logon events (success and failure), object access (failure), policy changes (success and failure), privilege use (failure), system events (success and failure), access to a host or networking device logged by user name and the time of access, and all other internal user actions. Anomalous behavior is audited and logged for purposes of evidence for law enforcement and/or attack recognition. Audit information is collected and stored in a secure manner to preserve the chain of evidence. If there is a failure of the audit system, automatic shutdown is initiated. 
     The gaming network is designed so that there is no single point of failure that would prevent remaining security features from operating when one is compromised. The gaming network also will continue to operate in the event of bridging to another network, such as the Internet. 
     Secure Initialization of Network Devices 
     The gaming network provides confidence that a network device is contacting a legitimate DHCP server rather than a spoofed server. The gaming network uses Internet Key Exchange (IKE) in one embodiment. There are a number of modes and phases of IKE. Phase I of IKE includes two modes, referred to as “main mode” and an “aggressive mode”. Phase II has a single mode referred to as “quick mode”. Main mode takes six packets to complete while aggressive mode takes 3 packets. Quick mode takes 3 packets to complete. In some embodiments, Phase I is used for initialization and Phase II is used to create security for subsequent traffic and messages.  FIG. 3  is a flow diagram illustrating the initialization of a network device using main mode of Phase I. 
     Phase I is used to authenticate devices to each other and to protect subsequent Phase II negotiations. In the following description, the network device is referred to as the initiator and the server is referred to as the responder. Referring to  FIG. 3 , at step  301 , the initiator sends a first IKE packet to the responder. The packet may or may not include vendor ID&#39;s (VID) that can inform the responder of the extensions the initiator supports. Each IKE message includes a mandatory Security Association (SA) that defines how to handle the traffic between the two devices. The SA of the initial packet lists the security properties that the initiator supports, including ciphers, hash algorithms, key lengths, life times and other information. At step  302 , the responder replies with an IKE packet that may or may not include a VID, but does include a mandatory SA payload. At this stage, the packets are not encrypted because there is still no key for encryption. 
     The third packet, at step  303 , is from the initiator to the responder and uses the Diffie-Hellman key exchange protocol. The packet contains a key exchange (KE) payload, a NONCE payload, and a certificate request (CR) payload. The public keys are created whenever the phase I negotiation is performed and are destroyed when the phase I SA is destroyed. The NONCE payload is a large random number that has not been used before on the network (“never-used-before”) and is useful in defeating replays. The CR payload includes the name of the Certification Authority for which it would like to receive the responder&#39;s certificate. (Note that the CR can be sent in the third and fourth packets or in first and second packets, as desired). 
     At step  304 , the responder returns its own KE, NONCE, and CR in the fourth packet. The third and fourth packets are used by each device to generate a shared secret using public key algorithms. Because only public keys are sent in this exchange, and no encryption key is yet available, the messages are still not encrypted. 
     At step  305 , the initiator uses the KE to generate a shared secret and uses it to encrypt the fifth message. The fifth message includes an Identification (ID) payload, zero or more certificate (CERT) payloads (or CRL) and a Signature payload (SIG) that is the digital signature that the responder must verify. The ID payload is used to tell the other party who the sender is and may include an IP address, FQDN (fully qualified domain name), email address, or the like. In an embodiment of the gaming network, it is an IP address. The CERT payload is optional if the initiator or responder cache the public key locally. In an embodiment of the gaming network, the public key is not cached locally and failure to receive a CERT payload is a failure of the negotiation. The SIG payload includes the digital signature computed with the private key of the corresponding public key (sent inside the CERT payload) and provides authentication to the other party. 
     At step  306 , the responder sends a message with its ID, CERT, and SIG payloads. When both the initiator and responder have successfully verified the other party&#39;s SIG payload, they are mutually authenticated. The result of the successful negotiation is the Phase I SA. 
     After the phase I negotiation is successfully completed, the phase II negotiation can proceed to create SA&#39;s to protect the actual IP traffic with an IPsec protocol. Each of the phase II packets are protected with the phase I SA by encrypting each phase II packet with the key material derived from phase I. Phase II in the gaming network is illustrated in  FIG. 4 . At step  401 , the initiator sends a message with a number of payloads. The message includes SA and NONCE payloads that are the keying material used to create the new key pair. As noted above, the NONCE payload includes random never-used-before data. The SA payload is the phase II proposal list that includes the ciphers, HMACs, hash algorithms, life times, key lengths, IPsec encapsulation mode, and other security properties. Optionally, the message may include IDi (initiators ID) and IDr (responders ID), which can be used to make local policy decisions. 
     At step  402 , the responder replies with a message with the same payload structure as the first message. The initiator replies with a HASH value at step  403 . After phase II is completed, the result is two SA&#39;s. One is used for inbound traffic and the other for outbound traffic. 
     Rekeying is done when the lifetime of the SA used for protecting network traffic expires. In one embodiment, PFS (perfect forward secrecy) protocol is used for rekeying. The network ensures the set of secret keys generated by one protocol message exchange is independent of the key sets generated by the other protocol message exchanges. This means compromise of one key set does not lead to compromise of the other sets 
     Additional protection for network traffic is provided by use of a “virtual private network” (VPN). As a result, all network traffic is protected, and not just TCP/IP traffic. 
     In an alternate embodiment, the network may be constrained to a particular regulatory jurisdiction. In this embodiment, a regulatory jurisdiction has its own private key and a multi-tiered approach is used to validate devices. During initialization, a combination key at an administrative location is used to sign messages and data. If there are attempts to communicate outside the jurisdiction, the lack of the regulatory jurisdiction key prevents communication. This is another security feature that is used to limit inside and outside attacks on the gaming network. 
     In one embodiment, the system uses a secure key server to store private keys and certificates. The secure key server requires multi-part passwords as described above for access and enablement. The secure key server is resistant to network or Internet attacks, denial of service attacks, and other software or protocol attacks. The secure key server is also resistant to physical attacks such as forced break-in attempts, changes in temperature, changes in pressure, vibration, attempts to disassemble the secure key server. In one embodiment, any attack attempt results in the destruction of stored keys, certificates, etc, to prevent compromise of the system. 
     In another embodiment, a physical transfer of certificates may be implemented as an additional security protection. No game machine or other device may be added to the system without a physical visit and installation of a certificate. In other words, a mere handshaking protocol is not sufficient to add a device onto the system. Rather, a potential new device will require a trusted person or persons to activate the device, install an appropriate certificate, and add it to the network. 
     Blocking Illegitimate Traffic 
     As described above, the gaming network uses IKE, IPsec, and VPN to protect legitimate traffic from mischief. The gaming network also provides systems to block illegitimate traffic. Firewalls are installed at choke points within the access and distribution layers to isolate network segments from one another. Firewalls can limit the spread of damage from propagating beyond the compromised network segment. The use of NONCE never-used-before random numbers also prevents illegitimate traffic by blocking replay of legitimate messages. IKE and protection of all post initialization traffic makes it more difficult for illicit messages to achieve successful delivery. 
     In addition to detecting false messages using the techniques above, the gaming network reduces the possibility of access to the network by blocking all unused IP ports. Only IP ports required for gaming operation are enabled. To further limit the ability of outside access to the gaming network, private IP addresses are used. Typically IP addresses provide global uniqueness with the intention of participating in the global Internet. However, certain blocks of addresses have been set aside for use in private networks. These blocks of IP addresses are available to anyone without coordination with IANA or an Internet registry. Since multiple private networks may be using the same block of IP addresses, they lack global uniqueness and are thus not suitable for connection on the global Internet. Private network hosts can communicate with all other hosts inside the private network, both public and private. However, they cannot have IP connectivity to any host outside of the enterprise. Allocation of private network IP addresses may be accomplished pursuant to RFC 1918 protocol. 
     In another embodiment, the volume of network traffic is monitored at each link and compared to expected flow rates and/or historical flow rates. Histograms may be generated so that analysis and comparison of flow rates may be accomplished. Heuristic algorithms may be implemented to determine if the flow rate is within an acceptable range. If not, a data leak or attack is assumed and appropriate alarms are triggered. Heavy flow areas can be disabled so that appropriate investigation can be made. 
     Detecting and Reacting to Attacks 
     Intrusion detection system (IDS) sensors and/or intrusion prevention systems are installed between the core, distribution, and access layers. IDS and intrusion prevention sensors may also be installed at choke points within the access and distribution layers to detect malicious traffic within these layers. One suitable IDS is “arpwatch” (www.securityfocus.com/tools/142) that monitors IP address changes, MAC addresses, flow rate changes, and other network activity and can be configured to notify an administrator when IP/MAC/DID address bindings change for a device on a gaming network. When a change is detected, automatic isolation procedures may be implemented to isolate the possible intrusion. Subsequent analysis and review by network administrators can determine appropriate responses. 
     The system may keep a physical map of the location of the IDS sensors so that when an intrusion is detected, the physical location of the attack can be immediately identified. Security can be dispatched to the location to apprehend the attackers, appropriate systems may be shut down or disabled, and perimeter measures can be taken to increase the chances of securing the attacker. 
       FIG. 5  is a flow diagram of one embodiment of the operation of the intrusion detection system of the gaming network. At step  501 , the gaming network is initialized and IP addresses are assigned to network devices. This may be accomplished using the technique described in  FIGS. 3 and 4  or by any other suitable technique. At step  502 , a mapping of the IP addresses of the network devices, their respective MAC addresses, and the DID is performed. This binding should remain stable through a session unless the core layer specifically initiates a change or if a regularly scheduled or anticipated change occurs. 
     At step  503 , the system monitors the network. Such monitoring may be accomplished by any suitable means for tracking IP/MAC/DID mapping. As noted above, one such method includes Arpwatch. At decision block  504 , it is determined if there has been any change to the IP/MAC/DID mapping. If the answer is no, the system continues monitoring the network at step  503 . If the answer is yes, meaning that there has been some change in IP/MAC/DID mapping, the system disables the IP address and the network device associated with the MAC address and DID in question at step  505 . This step of disabling may also include shutting down ports or sections of the network to contain or limit any presumed attack on the network. The system notifies the administrator at step  506  so that analysis and correction may begin. 
     In an alternate embodiment of the system, the mapping may be between any two of the parameters IP address, MAC, and DID. In addition, there may be multiple devices inside of the gaming machine. In some instances, the DID of the gaming machine may be used exclusively. In other instances, the DID of an associated device such as a reel controller, LED controller, CPU, safeRAM, hard drive, physical cabinet, printer, or other associated devices may be used singly or in combination with the gaming machine DID. Each associated device may have a unique ID (such as a 32 bit hex value) so that the combination of game machine DID and/or one or more associated device DID&#39;s results in a unique ID that is difficult to duplicate, we call this a “binding”. Fraudulent communications that lack the requisite binding will be detected easily. Further, malicious hardware that attempts to join the network will lack not only the correct device ID&#39;s but also the combination bindings described above. 
     In yet another embodiment, the DHCP server is pre-loaded with a list of valid IP addresses, MAC addresses, machine and associated device DIDs, and IP/MAC/DID bindings. If the game machine requesting initialization or permission to join the network is not on the pre-determined list, the machine is not permitted on the network and an attack is logged. An alarm can be triggered so that the attacker can be identified and captured when possible. 
     In some instances, it may be useful to use dynamically assigned IP addresses in a gaming network. In such a situation, it is still important to be able to identify with certainty that only valid devices are on the network. In one embodiment, globally unique identifiers (GUIDs) are used to identify managed switches at one or more levels of hierarchy. For example, the switch could be at the game cabinet level, a bank of machine level, and/or a casino level. The GUID is used to positively identify a valid managed switch. 
     Associated with each managed switch is what is referred to herein as a “collection” of devices associated with that switch. The DIDs and MAC addresses can be used to identify the devices as being valid members of the collection. The dynamically assigned IP address can then be mapped to the collection so that the members of the network are known, and communication with the collection and its constituent devices can occur. The IP addresses can be subnet IP addresses for members of the collection if desired. 
     GUIDs are registered at network creation and when valid devices are added to the system. Once registered, dynamically assigned IP addresses can be properly mapped for communication using the IP address if desired. 
     In another embodiment, each network device has its own GUID that is registered and may be mapped to a dynamically assigned IP address. If desired, the bindings described above may be implemented even with dynamically assigned IP addresses, once the proper mapping has been made using GUIDs. 
     Another embodiment takes advantage of GUIDs to create logical collections instead of physical collections. A logical collection may be disparate physically but may be useful for certain management, reporting, or game play operations. 
     By being able to uniquely identify devices and collections, it is possible to create filters that allow communication with subsets of network devices at levels from single devices to collections to all devices and anywhere in between. 
     An additional security feature of the gaming network requires a secure boot sequence within each gaming machine and server such that an initial boot is accomplished using code residing in unalterable media. The initial boot code verifies the operating system and all network services it includes. Consequently, network services will not be enabled until the full operating system has been verified as legitimate. 
       FIG. 6  is a flow diagram illustrating the boot initialization of a network device, such as a gaming machine in one embodiment of the gaming network. At step  601 , the device boots from a locally stored unalterable media. At step  602 , the network device establishes security for communication with a network host. This may be accomplished by the IKE phase I method described in  FIG. 3 . Once secure host communication is established, traffic security is established at step  603 . This may be accomplished by IKE phase II, as described in  FIG. 4 . 
     If any of the steps fail in this sequence, communication is terminated and a network administrator is notified. At step  604 , the network device submits its operating system for verification. Such verification may be by any desirable method and may be in addition to other network security features. At step  605 , the host receives the verification request and checks the operating system of the network device. 
     At decision block  606 , it is determined if the network device contains a legitimate operating system. If not, the device is disabled at step  607 . This process may initiate notice to a network administrator, as well as, disabling of some portion of the network associated with the device in an attempt to mitigate damage from an attack. If the operating system of the network device is legitimate at step  606 , the host enables the appropriate network services for the network device at step  608  and operation begins. As noted above, all traffic is protected in the gaming network to some degree. In addition, some traffic includes additional security checks. 
     In one embodiment, the game machine provides a secure boot and initial O/S verification as follows. EPROM verification software resides within an input/output processor (IOP). The verification software verifies all EPROMs on the IOP board (i.e., mains and personalities) upon application of power to the game machine. Next, after the application of power to the machine, the BIOS+ performs a self-verification on all of its code. Once satisfactorily completed, the board (e.g. a Pentium class board) begins executing code from the BIOS+contained in the conventional ROM device. This process verifies the conventional ROM device and detects any substitution of the BIOS+. 
     Upon boot-up of the processor, the BIOS+ executes a SHA-1 verification of the entire O/S that is presented. The digital signature is calculated and compared with an encrypted signature stored in a secure location on the game machine using, for example, the RSA private/public key methodology. If the signatures compare, the BIOS+ allows the operating system to boot, followed by the game presentation software. Next, display programs and content are verified, before being loaded into the IOP RAM to be executed for normal game operation. 
     During communication, each message is protected using the security of the gaming network. However, certain messages incorporate additional security checks even if the package is considered trustworthy. For example, code downloads may require that they be cryptographically signed and verified before executing. For messages such as these, the digital signature for the code is independent of and in addition to the authentication provided by VPN and the other network security features. In addition to the digital signature check and verification, the gaming network implements increasing number versioning of network downloaded updates so that rollback attempts may be mitigated or eliminated. 
     It may be desired to have some network communication links be wireless instead of hard wired. In such an environment, the gaming network includes wireless intrusion detection mechanisms detecting, for example, 802.1.1a/b/g devices. Such detection has scope beyond network attacks and may detect wireless attacks on the gaming establishment, even if not specifically targeting the gaming network. 
     It will be apparent from the foregoing that, while particular forms of the claimed invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the claimed invention. Accordingly, it is not intended that the claimed invention be limited, except as by the appended claims.