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Collaboration, Voice & AV · Intermediate

IP Phone Hardening

Disabling unnecessary features on IP phones, such as PC port access, web access and gratuitous ARP, to reduce attack surface.

Definition

In CUCM product-specific configuration, administrators can disable the PC port, gratuitous ARP, PC access to the voice VLAN, span to PC port, web access, settings access and unneeded services. Combined with 802.1X, signed firmware, LSCs and encrypted security profiles, these settings protect phones and the voice VLAN.

Example

Lobby phones have the PC port, web access and settings menu disabled.

Exam tip

Disabling Gratuitous ARP helps prevent ARP spoofing of the phone; disabling PC voice VLAN access stops PCs reaching the voice VLAN.

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