📩ICMP - Internet Control Message Protocol

Network layer, used by intermediary devices. Does updates, or error info for network issues.

Summary

ICMP is a very chatty protocol used in Ethical hacking in order to see which hosts are alive and which ones are going to respond.

ICMP Ping Command

• Echo

• Timestamp

• Information

• Subnet mask

Internet Protocol Uses ICMP

• Is Unreliable - it doesn't guarantee delivery

• Notifies the sender when something goes wrong

• ICMP error message - IP header and first 8 bytes

Error Codes

• Type 3 - Destination Unreachable Codes

• Type 5 - Redirect Codes

• Type 12 - Parameter Problem codes

• Type 11 - Time Exceeded Codes