Dive into ICMP, a powerful network layer protocol used to communicate updates or error information. Gain insight into ICMP, and how it is used by the Internet Protocol (IP) to see if it can get to its destination, acting as a scout, and then coming back and replying whether or not it was successful.
- [Instructor] Internet Control Message Protocol…resides in the network layer.…It's used by routers, intermediary devices or hosts,…to communicate updates or error information.…It's also used to troubleshoot network issues.…There are four types of query messages…that characterize the output generated by the ping command,…echo, timestamp, information, or subnet mask.…ICMP messages are transmitted within an IP datagram.…
We can see an ICMP ping request…where you will see an IP header, but within that,…you will see the ICMP message.…No data is exchanged…and there is no transport layer header.…Within an ICMP message, there is some commonalities,…type, code and checksum.…The contents will depend on the type…and whatever possible code you might see.…So, why do we use ICMP?…Internet protocol is unreliable…in that it doesn't guarantee delivery.…
So it's important to notify the sender…when something goes wrong.…ICMP is used to give feedback…about network problems that are preventing packet delivery.…For example, within the ICMP error message…
Note: Our Ethical Hacking series maps to the 18 parts of the EC-Council's certification exam. This course maps to the 02 Footprinting and Reconnaissance domain.
- Using competitive intelligence
- Hacking with search engines
- Using email for footprinting
- Getting social
- Mirroring websites
- Using Ping, Tracert, nslookup, and dig
- Taking footprinting countermeasures
- Pen testing for footprinting