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Does ICMP support redirection?
The ICMP Redirect message is used to notify a remote host to send data packets on an alternative route. A host SHOULD NOT send an ICMP Redirect message.
What is redirection message?
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.
When ICMP redirect message is used?
ICMP redirect messages are used by routers to notify the hosts on the data link that a better route is available for a particular destination. For example, the two routers R1 and R2 are connected to the same Ethernet segment as Host H.
What does ICMP redirect do?
ICMP redirect messages are used by routers to notify the hosts on the data link that a better route is available for a particular destination. Router R1 forwards the packet to router R2 and also sends an ICMP redirect message to Host H. This informs the host that the best route to reach Host 10.1.
How do you redirect a message?
A message can be redirected in several ways:
- The Redirect button on the standard toolbar of the Main window and of the Message viewer window.
- The Redirect option in the Message section of the Main menu or the Ctrl+F6 hotkey.
What is the purpose of an ICMP redirect message?
ICMP redirect messages are used by routers to notify the hosts on the data link that a better route is available for a particular destination.
How does ICMP send a redirect message to a host?
The gateway, G1, checks its routing table and obtains the address of the next gateway, G2, on the route to the datagram’s internet destination network, X. If G2 and the host identified by the internet source address of the datagram are on the same network, a redirect message is sent to the host.
How to disable ICMP redirects on Layer 3 interfaces?
In fact, for most networks it is a good practice to proactively disable ICMP Redirects on all Layer 3 interfaces, both physical, like Ethernet interface, and virtual, like Port-Channel and SVI interfaces. Use no ip redirects NX-OS interface-level command to disable ICMP Redirects on a Layer 3 interface.
Can a ICMP packet be used to attack a network?
There are certain cases where ICMP packets can be used to attack a network. Although this type of problem is not common today, there are situations where such problems do happen. This is the case with ICMP redirect, or ICMP Type 5 packet.
When to send a redirect message to a host?
If G2 and the host identified by the internet source address of the datagram are on the same network, a redirect message is sent to the host. 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.