Secure Routing and Antispoofing

This chapter covers both antispoofing and securing the routing protocol your routers use to exchange information. Antispoofing filters prevent external users from sending forged packets that act as if they come from your internal network. Many security controls use a packet’s source IP address to allow or deny access. By sending spoofed packets that look as if they originated on your internal network, attackers can manipulate or bypass these security controls.