|Project Description: ||Cloud computing is the key technology widely used across most of the organizations. The main advantage with cloud computing is that, the risk of infrastructure maintenance reduces a lot. Most of the service providers offer a wide range of services to their clients in the form of cloud services and the clients can use the same from a remote location. Apart from the list of advantages with cloud computing there are some limitations and security has a significant role among them. Providing security to the client’s information and data are the main challenge to the cloud service providers and there is lot research done in this context to provide the required security for the information and data. In general the services offered by the cloud service providers are accessible through the web and blocking the web traffic across the cloud access should be given top priority. The main aim of this project is to evaluate the cloud security against the firewall implementation under three different scenarios. OPNET IT guru is used as the simulation tool in this project and three scenarios are created in this context. First scenario has no security across the cloud, second scenario has the actual firewall implementation and this particular firewall allows all the required traffic, whereas the third scenario deals with the firewall implementation which discards the web traffic. Database and web applications are used as the required applications across the cloud to generate the traffic and now the firewalls will act on these applications. The performance of these applications is estimated against the firewall working conditions and the overall performance of the cloud is evaluated. All the three scenarios are compared against the metrics for the individual applications and also the performance of the cloud is estimated.