Application Level Gateway Limits

The application level gateway has several limitations.

• Its re-addressing of every authorized packet makes it much slower than a packet filter. A gateway is a potential bottleneck for network communications with the Internet. This can reduce the work efficiency of users of the protected network.
• The application level gateway normally requires a fair amount of effort to setup and maintain.
• It is limited to authorizing packets only from those applications specifically supported by the firewall. If your network suddenly has need for an Internet service for which your firewall has no proxy application, then you cannot use that service.
• The application level gateway is not perfect. No firewall can perfectly protect a network. However, the gateway's high level of security might lull you into believing that your network can never be hacked, which is not true. Any network can be hacked.