Disadvantages of Stateful Multi-Layer Inspection
A firewall such as the SMLI remains completely transparent to both users and applications. Consequently, SMLI firewall does not put extremely heavy processing overload on the host computer. Since it is rules based, SMLI firewall has the disadvantage that new applications may require new rules to be defined and implemented. However, the efforts are far lower than that involved in writing new proxies altogether, thus allowing SMLI firewall vendors to support a broad range of new Internet applications very quickly (may be as quickly as almost overnight).