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Cisco IOS DHCP Snooping Configuration

Cisco IOS DHCP Snooping Configuration

Learn how to configure DHCP Snooping on Cisco switches to prevent rogue DHCP servers from issuing malicious IP addresses.

Protecting Your Network with Cisco DHCP Snooping

DHCP Snooping is a Layer 2 security feature available on Cisco switches that prevents unauthorized DHCP servers from distributing IP addresses to clients.

Without DHCP Snooping, a rogue device could impersonate a DHCP server and redirect client traffic through malicious gateways.

Step 1: Enable DHCP Snooping Globally


Switch(config)# ip dhcp snooping

This enables the DHCP Snooping feature globally on the switch.

Step 2: Specify VLANs to Protect


Switch(config)# ip dhcp snooping vlan 10

This tells the switch to monitor DHCP traffic on VLAN 10.

Step 3: Configure Trusted Ports

Ports connected to legitimate DHCP servers must be marked as trusted.


Switch(config)# interface GigabitEthernet0/1
Switch(config-if)# ip dhcp snooping trust

All other ports remain untrusted and cannot send DHCP server responses.

Verification


show ip dhcp snooping
show ip dhcp snooping binding

Final Thoughts

DHCP Snooping is a fundamental security feature that should be enabled on all enterprise access layer switches.

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