What is the IP protocol number for ICMP?

The IP protocol number for ICMP (Internet Control Message Protocol) is 1. This number is part of the Internet Protocol suite, which assigns specific values to different protocols to help identify them within the IP header. ICMP is primarily used for error messaging and operational queries, such as ping and traceroute, which are essential for network diagnostics and troubleshooting.

By knowing that ICMP has a protocol number of 1, networking professionals can identify and differentiate ICMP traffic from other types of protocol traffic across networks. Understanding this detail is crucial in various scenarios, including configuring firewalls to allow or block specific types of traffic based on their protocol numbers, ensuring network reliability and performance.