Application gateway is one of the firewall systems. A service is provided by
different processes which maintain complete TCP connection state and
sequencing. Re-addressing of traffic for outgoing traffic appears to have
originated from the firewall, is performed often.
The following are the advantages of Application Level Gateways:
- Direct connections between internal and external hosts are disallowed.
- User-level authentication is supported.
- The application commands are analyzed inside the payload portion of the data
The following are the disadvantages of Application Level Gateways:
- Slower than packet filters
- Needs the internal client to know about them.
- Every possible type of connection can not be supported