C H A P T E R
9
Phone Hardening
To tighten security on the phone, you can perform tasks in the Phone Configuration window in
Cisco CallManager Administration. This chapter contains information on the following topics:
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Disabling the Gratuitous ARP Setting
By default, Cisco 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 of Cisco CallManager Administration.
Note
Disabling this functionality does not prevent the phone from identifying its default router.
Disabling Web Access Setting
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.
Cisco CallManager Security Guide
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