Command
Passive-Interface Default
Use
This command prevents EIGRP from forming adjacencies on specified interfaces on the router. Using no passive-interface default will allow EIGRP communication.
Syntax
Router(config-router)#passive-interface <interface>
Example

In this example, we will use passive-interface default to block all EIGRP adjacencies. Then we will allow communication through R2’s Fa0/0
R2(config)#do show ip route eigrp |
Here we enable passive-interface default on R2.
R2(config)#router eigrp 100 |
We can see there are no longer any EIGRP routes on R2.
R2(config-router)#do show ip route eigrp R2(config-router)# |
Now we will use no passive-interface fa0/0 to allow communication through R2’s Fa0/0
R2(config)#router eigrp 100 |
After that, we have routes coming in from Fa0/0 but not any other interface.
R2(config)#do show ip route eigrp |