From Managing Cisco Network Security

Introduction

A firewall is a security mechanism located on a network that protects resources from other networks and individuals. A firewall controls access to a network and enforces a security policy that can be tailored to suit the needs of a company.

There is some confusion on the difference between a Cisco PIX firewall and a router. Both devices are capable of filtering traffic with access control lists, and both devices are capable of providing Network Address Translation (NAT). PIX, however, goes above and beyond simply filtering packets, based on source/destination IP addresses, as well as source/destination TCP/UDP port numbers. PIX is a dedicated hardware device built to provide security. Although a router can also provide some of the functions of a PIX by implementing access control lists, it also has to deal with routing packets from one network to another. Depending on what model of router is being used, access lists tend to burden the CPU, especially if there are numerous access lists that must be referenced for every packet that travels through the router. This can impact the performance of the router, causing other problems such as network convergence time.

Cisco Systems offers a number of security solutions for networks, including Cisco Secure PIX Firewall series. The PIX firewall is a dedicated hardware-based firewall that utilizes a version of the Cisco IOS for configuration and operation. This chapter will introduce and discuss security features, Network Address Translation (NAT), Network Address Port Translation (NAPT, or referred to as PAT...


Products & Services
Network Appliances
Network appliances are inexpensive personal computers (PC) or computer boards that provide Internet access and promote network security. They lack many of the features of fully-equipped PCs, however.
Network Firewalls
Network firewalls protect computer networks against unauthorized use or attack. They permit or deny access to private network devices and applications, and represent an important part of an organization's overall security policy. Firewalls may be software applications, hardware devices (such as routers), or a combination of both. They include turnkey products that are relatively easy to install as well as complex, multi-layer installations that require the expertise of a certified network administrator. 
Network Security Services
Network security services determine vulnerability of networks to outside intruders, as well as maintain anti-viral and firewall updates and usage.
Wireless Network Components
Wireless network components are used to build or replace worn out devices within a wireless network.
Network Security Software
Network security software includes everything from remote access protection to firewall and security appliance solutions to email security to web filtering, monitoring, bandwidth protection, and all elements of computer network security/computer security.

Topics of Interest

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Introduction A firewall is a security mechanism located on a network that protects resources from other networks and individuals. A firewall controls access to a network and enforces a security...

Introduction A firewall can be described as a security mechanism located on a network that protects resources from other networks and individuals. It controls access to a network and enforces a...

Configuring NAT and NAPT Now that the interfaces have been named and security values have been assigned, and network connectivity has been established by configuring and testing the IP settings, NAT...

PIX and ASA Basics Cisco s PIX firewall is one of the industry s best-selling firewalls, providing customers with high levels of security, performance, and reliability. PIX, which stands for Packet...