# Basic ALG Configuration

All Application Layer Gateway (ALG) protocols are enabled by default on the security device. When you disable an ALG, all packets using that protocol are dropped.

To enable or disable an ALG, check or uncheck the corresponding check box, then click Apply. To configure parameters for the MGCP, H.323, SIP, SCCP, or AppleiChat ALGs, select the protocol from the list at the top of the page.

Note: This feature is CPU intensive. Under certain high-traffic conditions, its use can cause high CPU utilization.