This chapter provides information about phone hardening. To tighten security on the phone, you can perform phone hardening tasks in the Phone Configuration window in Cisco Unified Communications Manager Administration.
By default, Cisco Unified IP Phones accept Gratuitous ARP packets. Gratuitous ARP packets, which devices use, announce the presence of the device on the network. However, attackers can use these packets to spoof a valid network device; for example, an attacker could send out a packet that claims to be the default router. If you choose to do so, you can disable Gratuitous ARP in the Phone Configuration window.
Disabling this functionality does not prevent the phone from identifying its default router.
Web access disable
Disabling the web server functionality for the phone blocks access to the phone internal web pages, which provide statistics and configuration information. Features, such as Cisco Quality Report Tool, do not function properly without access to the phone web pages. Disabling the web server also affects any serviceability application, such as CiscoWorks, that relies on web access.
To determine whether the web services are disabled, the phone parses a parameter in the configuration file that indicates whether the services are disabled or enabled. If the web services are disabled, the phone does not open the HTTP port 80 for monitoring purposes and blocks access to the phone internal web pages.
PC voice VLAN access disable
By default,Cisco Unified IP Phones forward all packets that are received on the switch port (the one that faces the upstream switch) to the PC port. If you choose to disable the PC Voice VLAN Access setting in the Phone Configuration window, packets that are received from the PC port that use voice VLAN functionality will drop. Various Cisco Unified IP Phones use this functionality differently.
Cisco Unified IP Phones 7940G and 7960G drop any packets that are tagged with the voice VLAN, in or out of the PC port.
Cisco Unified IP Phone 7970G drops any packet that contains an 802.1Q tag on any VLAN, in or out of the PC port.
Cisco Unified IP Phone 7912G cannot perform this functionality.
Setting access disable
By default, pressing the Settings button on a Cisco Unified IP Phone provides access to a variety of information, including phone configuration information. Disabling the Setting Access setting in the Phone Configuration window prohibits access to all options that normally display when you press the Settings button on the phone; for example, the Contrast, Ring Type, Network Configuration, Model Information, and Status settings.
The preceding settings do not display on the phone if you disable the setting in Cisco Unified Communications Manager Administration. If you disable this setting, the phone user cannot save the settings that are associated with the Volume button; for example, the user cannot save the volume.
Disabling this setting automatically saves the current Contrast, Ring Type, Network Configuration, Model Information, Status, and Volume settings that exist on the phone. To change these phone settings, you must enable the Setting Access setting in Cisco Unified Communications Manager Administration.
PC port disable
By default, Cisco Unified Communications Manager enables the PC port on all Cisco Unified IP Phones that have a PC port. If you choose to do so, you can disable the PC Port setting in the Phone Configuration window. Disabling the PC port proves useful for lobby or conference room phones.
Set up phone hardening
The following procedure disables functionality for the phone.
To disable functionality for the phone, perform the following procedure:
In Cisco Unified Communications Manager Administration, choose Device > Phone.
Specify the criteria to find the phone and click Find or click Find to display a list of all phones.
To open the Phone Configuration window for the device, click the device name.
Locate the following product-specific parameters:
PC Voice VLAN Access
To review information on these settings, click the question mark that displays next to the parameters in the Phone Configuration window.
From the drop-down list box for each parameter that you want to disable, choose Disabled. To disable the speakerphone or speakerphone and headset, check the corresponding check boxes.