What is a ICMP redirect?

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.

What causes a router to send an ICMP redirect packet back to a host?

The ICMP redirect message indicates that the gateway to which the host sent the datagram is no longer the best gateway to reach the net in question. The gateway will have forwarded the datagram, but the host should revise its routing table to have a different immediate address for this net.

What is redirect host?

ICMP redirects are messages telling a host to deliver the next packet for the same destination IP address to a different router. This can happen for two reasons: There are two routers in the subnet, the first being the default gateway.

What does redirect host mean?

The redirect message advises the host to send its traffic for network X directly to gateway G2 as this is a shorter path to the destination. The gateway forwards the original datagram’s data to its internet destination.

Should I block ICMP?

Blocking ICMP is not only useless but most cases it is also harmful. There is several reason why you should not block ICMP if you are not absolute sure what you are doing and specially why you are doing. Yes icmp ping can help others to “profile” your network.

What is an ICMP request?

An ICMP request is a layered packet which is sent over the internet. It contains the Ether layer, which has the target and source MAC address in it. It also contains the IP layer, which has the source and target IP and also a couple of flags included. And at last it contains the ICMP data.

What is no IP redirects?

The “no ip redirects” Command. no ip redirects–this disables icmp redirect messages. 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.