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Chapter 11 Configuring Security Features
Configuring Cisco IOS Firewall IDS
Configuring Cisco IOS Firewall IDS
Cisco IOS Firewall Intrusion Detection System (IDS) technology enhances perimeter firewall protection
by taking appropriate action on packets and flows that violate the security policy or represent malicious
network activity.
Cisco IOS Firewall IDS identifies 59 of the most common attacks using “signatures” to detect patterns
of misuse in network traffic. It acts as an in-line intrusion detection sensor, watching packets and
sessions as they flow through the router, scanning each to match any of the IDS signatures. When it
detects suspicious activity, it responds before network security can be compromised, logs the event, and,
depending on configuration, sends an alarm, drops suspicious packets, or resets the TCP connection.
For additional information about configuring Cisco IOS Firewall IDS, see the “Configuring Cisco IOS
Firewall Intrusion Detection System” section of the Cisco IOS Release 12.3 Security Configuration
Guide.
Configuring VPNs
A virtual private network (VPN) connection provides a secure connection between two networks over a
public network such as the Internet. Cisco Secure Router 520 Series routers support site-to-site VPNs
using IP security (IPsec) tunnels and generic routing encapsulation (GRE). Permanent VPN connections
between two peers, or dynamic VPNs using EZVPN which create and tear down VPN connections as
needed, can be configured. Chapter 6, “Configuring a VPN Using Easy VPN and an IPsec Tunnel,” and
Chapter 7, “Configuring VPNs Using an IPsec Tunnel and Generic Routing Encapsulation,” show
examples of how to configure your router with these features. For more information about IPsec and
GRE configuration, see the “Configuring IPsec Network Security” chapter of the Cisco IOS Release
12.3 Security Configuration Guide.
For information about additional VPN configurations supported by Cisco Secure Router 520 Series
routers, see the EZVPN Server feature document. Cisco Secure Router 520 Series routers can be
configured to act as EZVPN servers, letting authorized EZVPN clients establish dynamic VPN tunnels
to the connected network.