# IP Address List or Address Book

The IP address list is also known as the address book.

ScreenOS classifies the addresses of all other devices by location and netmask/wildcard_mask. Each zone possesses its own list of addresses and address groups.

Individual hosts have only a single IP address defined and appear as a single computer icon in the IP address list. In IPv4 networks, individual hosts must have a netmask setting of 255.255.255.255, which masks out all but this host. In IPv6 networks, individual hosts must have a netmask of /128 and appear as a single computer icon.

IPv4 subnets have an IP address and a netmask/wildcard_mask (for example, 255.255.255.0 or 255.0.255.0) and appear as multiple computer icons in the IP address list. IPv6 subnets have an IP address and a prefix length (for example, /64) and appear as multiple computer icons in the IP address list.

## Viewing the Address Book

You can select the number of IP addresses per page you want to view from the List_per page drop-down list.

You can view the IP addresses per zone by selecting a zone from the drop-down list.

You can view the IP addresses using the filter to bring up the entries per the first letter (or number) of their name.

This page displays a table that lists all the IP addresses on the device and the following information for each one:

Name: Indicates the name of the IP address.

IP/Domain Name: Indicates the IP address or domain name of the network device.

Zone: If you are viewing all zones, this field indicates the zone to which the address belongs.

Comment: This field is optional and may or may not contain any information.

Configure: Click Edit to modify the IP address entry, or Remove to delete it.

Note: You cannot remove an IP address if it is being used by a policy; you must first remove the IP address from the policy.

## Configuring New IP Addresses

Before you can configure policies to permit, deny, or tunnel traffic to and from individual hosts and subnets, you must create entries for them.

### To Configure a New IP Address

Click New. For more information about configuring a new IP address, see IP Address Configuration.

### To Modify an IP Address Entry

1. In the Configure column, click Edit for the address you want to modify.

The Address Configuration page appears.

2. Enter the new address information, and then click OK to save your changes.

Note:Remember that the address name must be unique. Once you have defined an address and it is referenced by a policy, you can change the address name but not its zone, for example, from Trust to Untrust. To change its zone, you must first modify the underlying policy.

### To Remove an IP Address Entry

1. In the Configure column, click Remove for the address you want to delete.

A system message prompts you to confirm the removal.

2. Click Yes to confirm removal or No to cancel.

N ote:You cannot remove an IP address if it is being used by a policy; you must first remove the IP address from the policy.