text: in the following detailed description of example embodiments of the invention , reference is made to specific examples by way of drawings and illustrations . these examples are described in sufficient detail to enable those skilled in the art to practice the invention , and serve to illustrate how the invention may be applied to various purposes or embodiments . other embodiments of the invention exist and are within the scope of the invention , and logical , mechanical , electrical , and other changes may be made without departing from the subject or scope of the present invention . features or limitations of various embodiments of the invention described herein , however essential to the example embodiments in which they are incorporated , do not limit the invention as a whole , and any reference to the invention , its elements , operation , and application do not limit the invention as a whole but serve only to define these example embodiments . the following detailed description does not , therefore , limit the scope of the invention , which is defined only by the appended claims . fig1 illustrates atypical computer network environment , including a public network such as the internet at 101 , a private network 102 , and a computer network device operable to provide firewall and intrusion protection functions shown at 103 . in this particular example , the computer network device 103 is positioned between the internet and the private network , and regulates the flow of traffic between the private network and the public network . the network device 103 is in various embodiments a firewall device , and intrusion protection device , or functions as both . a firewall device or module within the network device provides various network flow control functions , such as inspecting network packets and dropping or rejecting network packets that meet a set of firewall filtering rules . as described previously , firewalls typically perform their filtering functions by observing communication packets , such as tcp / ip or other network protocol packets , and examining characteristics such as the source and destination network addresses , what ports are being used , and the state or history of the connection . some firewalls also examine packets to determine what application has established the connection , or act as a proxy device by processing and forwarding selected network requests between a protected user and external networked computers . firewalls often use “ signatures ” or other characteristics of undesired traffic to detect and block traffic that is deemed harmful or that is otherwise undesired . firewalls typically use sets of rules to filter traffic , such that what happens with any particular element of network data is dependent on how the rule set applies to that particular data . for example a rule blocking all traffic to port 6346 will block incoming traffic bound for that port on a server within the protected network , but will not block other data going to the same server on a different port number . similarly , a rule blocking traffic originating from a file sharing program such as shareaza will use patterns in the traffic to block shareaza traffic on port 6346 , but allow other traffic on port 6346 . but , in an environment where a firewall is implemented as a system distributed across multiple computers or nodes , such as in a large or complex system , the ability of multiple nodes to share a connection is limited by each node &# 39 ; s information regarding the connection , such as socket information , application information , user information , and the like regarding the connection . some embodiments of the invention therefore share information , such as information regarding rule sets , connections currently being processed , and other information among the various node sin the network . the nodes in a further example are configured such that one node takes a primary or master role , and manages the function of other nodes available to the cluster . in one such example , a firewall or intrusion protection system is implemented as a cluster or connected group of nodes that share processing traffic flowing through the firewall . fig2 shows a network with a distributed firewall , as may be used to practice some embodiments of the invention . here , a network such as the internet 201 is coupled to an internal network 202 by a firewall , 203 . the firewall 203 comprises an incoming traffic module 204 and an outgoing traffic module 205 that can perform functions such as load balancing and other firewall management functions . the firewall or intrusion protection rules are applied in firewall nodes 206 , which are connected to one another by network connections as shown . here the five nodes shown each comprise a separate computer system running an instance of firewall or related software , operable to apply rules to traffic to selectively permit or block traffic flowing between the internet 201 and the internal network 202 . in an alternate embodiment , some nodes such as nodes 1 , 2 , and 3 execute a firewall application , while other nodes such as 4 and 5 execute an intrusion protection system ( ips ) application . the nodes 204 and 205 are responsible for performing functions such as load balancing traffic routed to the firewall nodes 206 , ensuring that the nodes are able to work together efficiently to provide higher throughput capability than a single node . in a distributed firewall system such as this , determining what node is a master or coordinating node and what nodes are available to be added to a cluster can be a somewhat complex configuration task . one option is to manually explicitly set each node to perform a certain role in the cluster , but such a configuration has disadvantages such as the labor required and inability to recover if the designated primary node fails or does not boot properly . some distributed firewall embodiments therefore provide management of timing and coordination issues when establishing a distributed firewall cluster , enabling a cluster to self - configure into a working distributed firewall upon startup . in a more detailed example , a crossbeam linking the various nodes to one another provides various management functions , such as coordination of a designated primary node in the cluster . referring again to fig2 , some nodes such as nodes 206 are firewall nodes , and run instances of the distributed firewall . other nodes , such as nodes 204 and 205 perform functions such as providing external network ports , toad balancing , etc . additional nodes ( such as additional nodes 206 ) in a further embodiment provide control functions , file server , and other configuration / resource functionality to form a crossbeam architecture supporting the distributed firewall system . the crossbeam control nodes here monitor the nodes available to the system , and signal the node designated as the primary node so that the signaled node operates as the primary node rather than a secondary node . the designated primary node then creates a cluster , while other nodes are informed which node is the primary node and register with the primary node as they become operational to join the cluster . such a configuration works well when all nodes are operational , but if the primary node fails to boot , the crossbeam can be unaware and unable to recover in some instances . further , if the crossbeam nominates a new master node on reboot of the distributed firewall system , the old nodes that were part of the distributed firewall will still attempt to contact the old primary node and will not join the new cluster . some embodiments of the invention therefore include features enabling a distributed firewall cluster to better manage nodes trying to form a cluster , such as eligible nodes notifying the crossbeam system when such a node is up and is available to be designated as a primary node . the crossbeam system can therefore manage designation of a primary node , preventing problems such as split clusters and no clusters from forming . split clusters can form when a system reboots and has a change in configuration , such as when a node is added to increase performance or a replacement node is added to a system . for example , consider a booting system in which the crossbeam starts the nodes in an order , and designates the new node as the primary node . the new node recognizes that it is not in an existing cluster and reports to the crossbeam that it is not therefore eligible to be a primary node . this prevents the new node from forming its own cluster . the other two nodes then start up and report they are eligible to be the primary node , as they have knowledge of the previous firewall cluster . the crossbeam system can therefore change the primary node to one of the two nodes reporting eligible , sending notice of the primary node designation to the other node in the previous cluster on that it knows it &# 39 ; s a secondary node and knows the identity of the primary node . the new node also receives notice that it &# 39 ; s a secondary node from the crossbeam , and receives knowledge of the designated primary node that is used to connect to the primary node and join the cluster . in a more detailed example , the knowledge of the primary node sent to the new node includes an ip address of the primary node , and a password or other such credential enabling the node to associate itself with the primary node . in another example , a new cluster is booted for the first time , and no existing cluster information is therefore stored on any nodes in the distributed firewall . in this case , all nodes will boot and report that they are ineligible to be the primary node , and the system will essentially stall with no designated primary node . the nodes in this example are therefore further configured to start reporting that they are primary eligible if they have been booted for a certain period of time ( such as five minutes , 10 minutes , or any other suitable period ) without receiving notice from the crossbeam that a node has been designated as the primary node . one of the nodes can then be assigned as the primary node , and the other new nodes can be notified of the primary node &# 39 ; s identity as before , using an ip address and password to join the cluster by contacting the primary node . if a node is told to be a primary node and forma cluster , such as by being configured as the primary in the crossbeam system before it times out and reports itself as primary eligible , the designated node ensures that its status is “ primary eligible ”. this prevents other nodes from timing out and claiming primary eligible status , forming a split cluster in the event of a long boot sequence or timeout . once the designated primary node is booted and operational , it reports that it is the primary node rather than primary eligible . fig3 illustrates a typical configuration cycle of a distributed firewall , consistent with an example embodiment of the invention . the flowchart is divided into two parts initial formation of a distributed firewall cluster at 301 , and addition of a new node at 302 . at 303 , a new distributed firewall system boots for the first time , and the nodes all report ineligible to serve as the primary node as they have no knowledge of membership in an existing cluster . at 304 , the nodes reach timeout , and begin to report themselves eligible to be the primary node . the crossbeam system assigns one of the nodes as the primary node at 305 , and sends information regarding the primary node to the other nodes . the other nodes join the cluster at 306 , and the cluster is operational . at 307 , the distributed firewall system is upgraded by adding one or more additional nodes to the cluster . to add the new node , the system is shut down and the new node hardware is installed at 307 . the system is restarted at 308 , and the new node boots and reports ineligible to be a primary node at 309 , as it has no knowledge of being a part of an existing cluster . the other nodes in the network report eligible to be the primary node at 310 , as they were previously part of the cluster , and optionally one of the nodes reports back as the primary node . the crossbeam system assigns a primary node at 311 if needed , such as where no existing node has reported primary but the nodes have reported eligible to be the primary node , such as where a failed primary node is being replaced . once the cluster is started and a primary node has been identified , the crossbeam notifies the new node to the existing cluster &# 39 ; s primary node , and provides primary node information including primary node ip address and security credentials to join the cluster at 312 . these examples illustrate how management of nodes in a cluster , including management of a primary node , can be employed to prevent a variety of timing and other problems in configuration of a distributed firewall cluster . although specific embodiments have been illustrated and described herein , it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown . this application is intended to cover any adaptations or variations of the example embodiments of the invention described herein . it is intended that this invention be limited only by the claims , and the full scope of equivalents thereof .