Firewall is showed in port no 7 and Google search is likewise verified in port no 7 so I am puzzled around exactly how precisely ICMP use the port number.

You are watching: Why is it that an icmp packet does not have source and destination port numbers

Regards,Bhushan


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Port numbers are a feature of carry layer protocols such as TCP and also UDP. ICMP is really component of the internetworking layer (IP), so that attribute doesn"t exist at that layer.

And yes, I understand that ICMP is encapsulated in IP, but it still is thought about component of the internetfunctioning layer. That simply reflects the restrictions of the version. To quote from RFC 792:

ICMP, uses the standard support of IP as if it were a higher level protocol, however, ICMP is actually an integral component of IP, and should be applied by every IP module. .


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answered Jun 5 "18 at 14:25
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Ron TrunkRon Trunk
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ICMP is IP protocol 1, TCP is 6 and also UDP is 17. So these are all different protocols with various actions.TCP and UDP have Ports, ICMP does not.TCP and also UDP have actually an Echo Service on Port 7, periodically dubbed TCP-Ping/UDP-Ping, yet they have nothing to carry out via ICMP. Maybe this is your confusion.


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edited Nov 1 "18 at 19:04
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Banghua Zhao
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answered Jun 5 "18 at 14:03
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Winnie TiggerWinnie Tigger
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TCP and also UDP are transport protocols that usage port numbers to multiplex their usage in between applications or processes.

This means, your web browser using HTTP over TCP deserve to e.g. connect multiple times to the exact same web server. While the location port is the same (default for HTTP: 80), various source ports are provided for each socket link.

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In the same method, different applications have the right to use the exact same multiplexing, of course. On the server side tbelow have the right to be different solutions on various TCP ports - HTTP on 80, FTP on 21, SMTP on 25, and so on. Or - using non-typical ports - also different web servers on ports 80 and also 8000, for instance.

Without ports, tbelow can be just a solitary TCP link in between any type of 2 hosts, or a solitary TCP business running on a server. (Likewise with UDP or any type of other transfer protocol.)

ICMP is not a transport protocol but a component of the IP protocol. It is used for signaling between hosts. Messages that can be transmitted include

Desticountry unreachable (a rexternal signals that it"s unable to forward in the direction of the destination, a organize rejects a packet, or similar)Restraight message (a router desires the resource to usage another gateway)Time exceeded (a packet has surpassed its lifetime/hop count and also was dropped)Echo request / Echo reply (provided byping)