An attacker attaches a rogue router in a network. He wants to redirect traffic to a LAN attached to his router as part of a man-in-the-middle attack. What measure on behalf of the legitimate admin can

OSPFv3 by itself does not prevent rogue routers - authentication must be explicitly enabled regardless of which OSPF version is used.

Configuring routing protocols with authentication (such as MD5 for OSPF, EIGRP, or BGP) ensures that routing updates are accepted only from verified, legitimate routers. Without authentication, a rogue router can freely advertise false routes and divert traffic through the attacker's device. This is the primary and standard mitigation against rogue router man-in-the-middle attacks.

Traffic redirection via routing protocols can occur without admin permission if routers lack authentication, making this statement technically incorrect.

Disabling all routing protocols and using only static routes is operationally impractical in most networks and is not a scalable or standard security mitigation.