Intrusion Prevention Services Functional Overview - Cisco FirePOWER ASA 5500 series Configuration Manual

Chapter 1 Introduction to the Security Appliance
VPN Functional Overview
A VPN is a secure connection across a TCP/IP network (such as the Internet) that appears as a private
connection. This secure connection is called a tunnel. The security appliance uses tunneling protocols to
negotiate security parameters, create and manage tunnels, encapsulate packets, transmit or receive them
through the tunnel, and unencapsulate them. The security appliance functions as a bidirectional tunnel
endpoint: it can receive plain packets, encapsulate them, and send them to the other end of the tunnel
where they are unencapsulated and sent to their final destination. It can also receive encapsulated
packets, unencapsulate them, and send them to their final destination. The security appliance invokes
various standard protocols to accomplish these functions.
The security appliance performs the following functions:
•
•
•
•
•
•
•
•
The security appliance invokes various standard protocols to accomplish these functions.

Intrusion Prevention Services Functional Overview

The Cisco ASA 5500 series adaptive security appliance supports the AIP SSM, an intrusion prevention
services module that monitors and performs real-time analysis of network traffic by looking for
anomalies and misuse based on an extensive, embedded signature library. When the system detects
unauthorized activity, it can terminate the specific connection, permanently block the attacking host, log
the incident, and send an alert to the device manager. Other legitimate connections continue to operate
independently without interruption. For more information, see Configuring the Cisco Intrusion
Prevention System Sensor Using the Command Line Interface.
OL-10088-01
For UDP or other connectionless protocols, the security appliance creates connection state
information so that it can also use the fast path.
Data packets for protocols that require Layer 7 inspection can also go through the fast path.
Some established session packets must continue to go through the session management path or the
control plane path. Packets that go through the session management path include HTTP packets that
require inspection or content filtering. Packets that go through the control plane path include the
control packets for protocols that require Layer 7 inspection.
Establishes tunnels
Negotiates tunnel parameters
Authenticates users
Assigns user addresses
Encrypts and decrypts data
Manages security keys
Manages data transfer across the tunnel
Manages data transfer inbound and outbound as a tunnel endpoint or router
Cisco Security Appliance Command Line Configuration Guide
VPN Functional Overview
1-5