Reject ICMP redirects

The Internet Control Message Protocol (ICMP) offers features that can ensure that traffic gets from its source to its destination as efficiently as possible, but it can also help attackers hijack existing sessions.

ICMP redirects are intended to provide a mechanism for a router to let a client know about a better way to reach the target system, but they are rarely needed in private networks, and attackers can use them to trick the client into communicating with the wrong system.