In this article we will discuss Firewalls – Network Security, will make brief discussion on Firewalls – Network Security, In last article we discuss about Enable Enable SSH.
A firewall is one of the most effective security tools available for protecting users from external threats. Network firewalls reside between two or more networks, control the traffic between them, and help prevent unauthorized access. Host-based firewalls or personal firewalls are installed on end systems. Firewall products use various techniques for determining what is permitted or denied access to a network. These techniques are:
Packet filtering – Prevents or allows access based on IP or MAC addresses
Application filtering – Prevents or allows access by specific application types based on port numbers
URL filtering – Prevents or allows access to websites based on specific URLs or keywords
Stateful packet inspection (SPI) – Incoming packets must be legitimate responses to requests from internal hosts. Unsolicited packets are blocked unless permitted specifically. SPI can also include the capability to recognize and filter out specific types of attacks, such as denial of service (DoS)
Firewall products may support one or more of these filtering capabilities. Firewall products come packaged in various forms, as shown in the figure. Click each type to see more information.