Still, the more the firewall does, the more that can go wrong. The more the services, the larger the log file. The more people logging into the firewall box to administer it, the greater the possibility a mistake will be made. They are still around today. We have to keep in mind that security mechanisms added in parallel with each other do not usually increase security.
Adaptive firewalls tie filters, circuit gateways and proxies together in series.
For example, the administrator may decide that the security of an application gateway is required for setting up an FTP connection and processing the commands. During the actual file transfer, however, he may decide that speed is more important, thus dropping down to the granularity of a packet filter. In the world of prevention, detection and response systems, firewalls are primarily prevention systems. In reactive firewalls, intrusion detection and help desk products work in concert to allow the firewall to be more active than passive. As business requirements change and threats and risks from the Internet grow, firewalls can certainly keep up.