23. EIGRP Passive Interfaces
++++ Configuring EIGRP Security (Passive) ++++
interfaces whose network is advertised but is not sending out hellos (Hello is disabled)
Need to make all interfaces to Passive first
interface connected to other router should be excluded to passive interfaces
Router(config)#router eigrp 100
Router(config-router)#passive-interface default //making all interfaces into passive
Router(config-router)#no passive-interface serial 0/0 //exclude serial 0/0 interface in passive
Router(config-router)#exit