Recommended Minimum IOS Security Settings

This section deals with the basic minimum configurations that all enterprises should employ on their routers. Although some of the commands explained in this section are disabled by default, the administrator is urged to deny specifically those services and routes that are not needed. The following topics are covered:

  • Denying RFC 1918 routes

  • UDP and TCP servers

  • Finger service

  • IP unreachables

  • ICMP Redirect messages

  • Directed broadcasts

  • Proxy Address Resolution Protocol (ARP)

  • IP Unicast

  • IP source routing

Denying RFC 1918 Routes

All border routers within a company that is concerned with security should have some specific routes denied. RFC 1918 defines the ranges of IP addresses available for use on the Internet, ...

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