If a firewall rule does not allow the connection to be established by a DENY, the ASA normally sends a silent drop packet. This behaviour is not always suitable from a usability point of view for the clients in the LAN and their applications. For this purpose, a reset packet can be sent with the command service resetinbound interface "interface_name" and service resetoutside instead of drop.

An example is as follows:

conf t service resetinbound interface LAN service resetoutside end wr mem