Chapter 26 - Address Translation

Abstract

NetScreen is well known for its firewall and virtual private network (VPN) technologies primarily due to the Application-Specific Integrated Circuit (ASIC)-based design of most of their core features, including address translation. This chapter focuses on how the address translation features of NetScreen products have evolved from a simple physical interface translation (Screen OS 2.5 and below) to a solution capable of handling complex address translation design requirements. High-level network address translation (NAT) is the ability to masquerade one Internet Protocol (IP) address from another. This functionality is completely transparent to the users. NAT provides the ability to hide the originating IP address thus providing an extra layer of security to protect the host's identity. NAT provides a short-term solution to the depleting IP v.4 addresses on the Internet. NAT provides the ability to utilize one IP for several thousand devices thus conserving non-RFC 1918 IP addresses. With the cost of NAT devices going down each year and the increase in Internet usage, it is not surprising that NAT is a widely used feature.