Wassim

Security can be enforced with scalable network design and cryptography. Cryptography, and more precisely cipher suites, help achieve the three pillars of computer and network security: confidentiality, integrity and authenticity. They are also called the security Triad. Confidentiality is achieved through encryption, Integrity is achieved through hash, signatures and MAC, Authenticity is achieved through hash, certificates and MAC. Encryption cryptography is a wonderful world Prior to encrypt and decrypt messages, it is assumed that both the sender and the receiver hold a copy of the encryption key K. They can exchange it by phone, on a CD, on a USB drive,… The way encryption works is by using the mathematical XOR function (its mathematical symbol is ⊕). A message M is XORed with a key K to produce an encrypted message C. At the receiver, the encrypted message C is XORed with the same key K to reproduce the original message M. The input of an encryption algorithm is called the pla...

The following are some of the most important OSPF knowledge gems, which I’ve condensed in a single tutorial. Let us start first with looking into link state algorithms. Link State Protocols: The Dijkstra Algorithm Each router calculates the lowest cost path to each other router. Routers exchange link states. They send information about their connected links to all the other routers by flooding their links. Flooding means that whenever a router receives information on one interface, it sends it out of all the other interfaces. Flooding has the associated risk of creating loops. When there is a link failure or a topology change, the information is flooded to all other routers. All routers re-run the Dijkstra algorithm. How the Dijkstra algorithm works To determine the shortest path from router R1 to all other routers, we do the following: draw a table for R1, with the following rows: Shortest Path set, Candidate, Selected Shortest Path Set : the shortest path we find after...