Rascals are always sociable, and the chief sign that a man has any nobility in his character is the little pleasure he takes in others company. Arthur Schopenhauer

In order to improve the resiliency of their network at the routing level, network administrators use the FHRP family of protocols in most cases. However, in most cases, the configuration of FHRP protocols is left by default, which opens the way for exploitation.

FHRP (First Hop Redundancy Protocol) — is a family of network protocols that allows multiple physical routers to share/maintain a single virtual IP address, in order to increase the fault tolerance of the local network. This virtual address will be assigned as the default gateway address for the end hosts. The most common FHRP class protocols are HSRP, VRRP and GLBP, the security of which I will discuss in this article. FHRP Nightmare. Pentesting redundancy systems like a devil