ROUTE POISONING

AIM: To implement route poisoning within a network to prevent routers from sending packets over invalid route.DESCRIPTION:

Route poisoning is a method to prevent routing loops within computer networks. Distance-vector routing protocols in computer networks use route poisoning to indicate to other routers that a route is no longer reachable and should be removed from their routing tables. When the protocol detects an invalid route, all of the routers in the network are informed that the bad route has an infinite route metric. RIP (Routing Information protocol), use a maximum hop count to determine how many routers traffic must go through to reach the destination. Each route has a hop count number assigned to it which is incremented as the routing information is passed from router to router. A route is considered unreachable if the hop count exceeds the maximum allowed. Route poisoning is a method of quickly removing outdated routing information from other router's routing tables by changing its hop count to be unreachable (higher than the maximum number of hops allowed) and sending a routing update.

The existing distance information exchange among neighboring nodes for the seeking of routing paths. In many distance-vector-based implementations, e.g., those based on RIP, each node maintains a routing table in which each entry is associated with a tuple, denote some unique destination node, an estimated minimal cost to send a packet to destination node, and the next node along the minimal-cost path to the destination node.

SOFTWARE REQUIREMENTS

Operating system : Windows Vista Language : C

IMPLEMENTATION:

ALGORITHM / TECHNIQUE:

ROUTING TABLE:

The Routing table contains the information of the shortest distance between the source and Destination nodes and the next hop in that particular path.

ESTIMATE TABLE:The estimate table is a two dimensional array that contains the routing information for all the nodes in the network.

We maintain an adjacency matrix that denotes the link between the nodes. The entry 1denotes a direct link between the nodes and 0 the vice versa.

The basic procedure carried out by every entity (i.e., router) that participates in the routing protocol is as follows: Keep a routing table (or more accurately, a forwarding table) with an entry for every possible destination network. Each routing table entry contains the destination network, the distance D (also called a 'metric' or 'cost') to reach the destination, and the 'next-hop' router G that is the next router on the chosen path to that destination. A routing update must be sent to every neighbor. The update is a set of messages that contain all of the information from the routing table. It contains an entry for each destination network, with the distance to reach that destination.

When a routing update arrives from a neighbor, add the cost associated with the network (i.e., link) that is shared. (This should be the network over which the update arrived.) Call the resulting distance D'. Compare the resulting distances with the current routing table entries to that same destination network N. If the new distance D' for N is smaller than the existing value D, adopt the new route. That is, change the table entry for N to have metric D'.

Once when a node is declared to be poisoned, it is to be intimated to all the other nodes in the network to avoid sending packets of information to some invalid node. So all the nodes are information about the bad route by making the shortest path as 0 .Hence there exists no path between the poisoned node and other nodes in the network.

Here we display the routing table at each node separately in order to understand the updation of information in the routing tables. Only after the information is sent to the node, it comes to know about the bad route otherwise the path still exists between the nodes.The final estimate table after updating all the routing tables will not have any path between them.

CONCLUSION:

Thus a program to overcome Route poisoning within the network involving dynamic routing algorithm is implemented to improve the security of data transmission. We define the eavesdropping avoidance problem as Follows: Given a graph for a network under discussion, a source node, and a destination node, the problem is to minimize the path similarity without introducing any extra control messages, and thus to reduce the probability of eavesdropping consecutive packets over a specific link and avoid the infinite loops within the network.