What is ICMP redirection enabled?

An ICMP redirect message is an out-of-band message that is designed to inform a host of a more optimal route through a network, but possibly used maliciously for attacks that redirect traffic to a specific system.

How do I disable ICMP redirects in Linux?

Configure the host system to ignore IPv4 ICMP redirect messages.

  1. Open the /etc/sysctl. conf file.
  2. If the values are not set to 0 , add the following entries to the file or update the existing entries accordingly. Set the value to 0 .
  3. Save the changes and close the file.
  4. Run # sysctl -p to apply the configuration.

How do I stop IP redirects?

What are IP redirects?

Redirects happen when a router recognizes a packet arriving on an interface and the best route is out that same interface. In that case the router sends an icmp redirect back to the source telling them about a better router on the same subnet.

What is no mop enabled?

By default, MOP is enabled on all Ethernet interfaces, and disabled on all other type of interfaces. So if you don’t need MOP, you have to explicitly disable it on all interfaces, like recommended in the official Cisco Guide to Harden Cisco IOS Devices. If the output does not include “no mop enabled”, MOP is enabled!

What does no ip redirect do?

On the layer 3 switch that is acting as the gateway, simply disable IP redirects on the interface by entering “no ip redirects”. When that is done, the gateway will now follow its routing table and not worry about trying to inform the originating device about a better route.

What is ICMP and IGMP?

ICMP is abbreviation for Internet Control Management Protocol and IGMP is abbreviation for Internet Group Management Protocol. While ICMP uses unicast Routing for error detection and notification messages, IGMP is used by hosts to join and leave Multicast groups.