ICMP packets don’t have source and destination port numbers because ICMP is not a transport-layer protocol and doesn’t deliver data to applications or ports at all; it carries control and error messages between network devices at the network layer, so ports would serve no purpose.

Quick Scoop

“Ports are for talking to programs ; ICMP is for talking to the network itself.”

ICMP rides directly on top of IP and is used for things like ping , “destination unreachable,” and “time exceeded,” which are all about the health of the network, not about which application on a host should get the data.

Because of that, ICMP identifies its messages with Type and Code fields instead of port numbers, and the operating system’s networking stack handles them internally rather than handing them to a user-level application via a port.

Where ports fit in the stack

Think of the classic TCP/IP stack:

  • Application layer: HTTP, DNS, SSH, etc.
  • Transport layer: TCP/UDP use ports for process-to-process delivery.
  • Network layer: IP + ICMP move packets and report errors between hosts/routers.

Port numbers belong to the transport layer , where the problem is: “Which process on this host should receive this segment?”

ICMP’s problem is: “How do I report an error or send control info to that host or router?”—no specific process or socket is targeted.

So:

  • TCP/UDP need ports → multiple applications share one IP, each with its own port.
  • ICMP talks to the IP layer itself → the kernel’s networking code consumes ICMP, not an app bound to a port.

How ICMP identifies messages instead of ports

Instead of ports, ICMP has:

  • Type : what kind of message (echo request, echo reply, destination unreachable, time exceeded, etc.).
  • Code : sub-reason within that type (e.g., different reasons for destination unreachable).
  • For echo ping: Identifier and Sequence Number to match requests and replies, especially when multiple pings are in flight.

These fields let the OS:

  • Recognize what ICMP message this is.
  • Match replies to the right request (so your ping output lines up properly).
  • Handle routing, diagnostics, or error reporting without ever needing a port number.

Why ports would make no sense for ICMP

Here’s why you don’t want ports in ICMP:

  1. Wrong layer, wrong job
    ICMP is defined as a network-layer control protocol for IP; it reports issues like unreachable networks, TTL expiration, and parameter problems that concern the path between hosts, not any specific application socket.

  1. The OS, not user apps, is the real “receiver”
    ICMP messages are consumed by the network stack in the kernel.

    • It may then notify the appropriate TCP or UDP socket that something went wrong (e.g., “destination unreachable”).
    • But that mapping is inferred from the embedded IP + TCP/UDP header inside the ICMP error, not from a separate ICMP port field.
  1. Error ICMP already carries the needed context
    ICMP error messages include part of the original packet (IP header + at least the first 8 bytes of transport header). The kernel can see the original TCP/UDP ports there and map the error back to the correct connection, so adding ICMP ports would just be redundant.
  1. Echo messages still don’t need ports
    Even for echo (ping), where there is a clear “conversation,” the Identifier and Sequence fields are enough to distinguish concurrent pings and track replies; there’s no application multiplexing problem to solve, so ports add no value.

Mini example to make it concrete

Imagine you run ping 8.8.8.8:

  1. Your OS creates an ICMP echo request (Type 8, Code 0).
  1. It sets an Identifier and Sequence Number so it can recognize the reply later.
  1. The packet is wrapped in an IP packet and sent to 8.8.8.8 with protocol “ICMP” (IP protocol 1), not TCP or UDP.
  1. The remote host’s IP layer sees protocol = ICMP and hands it to its ICMP module—no port lookup.
  2. The reply echo (Type 0, Code 0) comes back with the same Identifier/Sequence so your ping program knows “this is my reply for packet #N.”

At no point is there a need to say “send this ICMP message to port 12345” because the recipient is the host’s IP/ICMP stack , not a user-space app listening on a port.

Key takeaway (TL;DR)

  • Ports exist to distinguish applications at the transport layer (TCP/UDP).
  • ICMP is a network-layer control protocol , used by hosts and routers to exchange error and diagnostic info.
  • ICMP uses Type/Code (+ Identifier/Sequence for echo) instead of ports, and is handled directly by the OS networking stack, so source/destination port numbers are unnecessary and intentionally absent.

Information gathered from public forums or data available on the internet and portrayed here.