These firewalls, many of which are
still used and deployed today, provided organizations with a quick and dirty way to filter
Internet traffic, but did not allow for a high degree of customization because of their
static nature.
The development of software-based firewalls coincided with the need for simpler management
interfaces and the capability to make software changes to firewalls quickly and
easily. Firewall products such as CheckPoint, Cisco, PIX, Sonicwall, and other popular firewalls
are all software-based. ISA Server itself was built and developed as a software-based
firewall, and has the ability to perform the traditional packet filtering that has become a
virtual necessity on the Internet today.
More recently, however, holes in the capabilities of simple packet-based filtering technology
have made a more sophisticated approach to filtering traffic for malicious or spurious
content a necessity. ISA Server responds to these needs with the capabilities to perform
Application-layer filtering on Internet traffic.
10 CHAPTER 1 Introducing ISA Server 2006
Understanding the Growing Need for Application-Layer Filtering
Nearly all organizations with a presence on the Internet have put some type of packetfiltering
firewall technology into place to protect the internal network resources from
attack.
Pages:
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81