Cisco Systems ISA550 Manual De Usuario

Configuring Zones

Cisco ISA500 Series Integrated Security Appliances Administration Guide

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Use the Networking > Zones page to configure a security zone, which is a group of 
interfaces to which a security policy can be applied. The interfaces in a zone share 
common functions or features. For example, two interfaces that are connected to 
the local LAN might be placed in one security zone, and the interfaces connected 
to the Internet might be placed in another security zone.

The interfaces are IP-based interfaces (VLANs, WAN1, WAN2, and so forth). Each 
interface can only join one zone, but each zone with specific security level can 
have multiple interfaces. 

Refer to the following topics:

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We recommend that you configure the zones before you configure WAN, VLAN, 
DMZ, zone-based firewall, and security services.

The security level for the zone defines the level of trust given to that zone. The 
security appliance supports five security levels for the zones as described below. 
The greater value, the higher the permission level. The predefined VPN and 
SSLVPN zones have the same security level. 

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Trusted(100): Offers the highest level of trust. The LAN zone is always 
trusted. 

•

VPN(75): Offers a higher level of trust than a public zone, but a lower level 
of trust than a trusted zone, which is used exclusively by the predefined 
VPN and SSLVPN zones. All traffic to and from a VPN zone is encrypted. 

•

Public(50): Offers a higher level of trust than a guest zone, but a lower level 
of trust than a VPN zone. The DMZ zone is a public zone. 

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Guest(25): Offers a higher level of trust than an untrusted zone, but a lower 
level of trust than a public zone. Guest zones can only be used for guest 
access.