ICMP

[Joe Abley]

Hi there,

You're asking questions that you could really much more easily answer yourself. For example, you're using Wireshark, which is a tool expressly designed to decide ICMP messages and tell you what they are, but you're using it just to capture packets so that you can send them to a list in an attachment to ask other people to decode them for you. It'd be much more straightforward (and you would get a better answer) if you just used the tool you're already using to decode them.

ICMP carries control messages between endpoints that are communicating on the Internet. The messages can be sent for various reasons. There is no good general answer to your question beyond "it depends" which I sense will not be helpful.

If you're not familiar with ICMP, no answer on this list is going to be better than learning what it is, and what it is for in a general sense. Perhaps start here:

  https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol <https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol>

If you'd like a more comprehensive treatment, I strongly recommend this book:

  https://www.amazon.ca/Internetworking-TCP-One-Douglas-Comer-ebook/dp/B00EAZ5HSG/ref=sr_1_2 <https://www.amazon.ca/Internetworking-TCP-One-Douglas-Comer-ebook/dp/B00EAZ5HSG/ref=sr_1_2>

Incidentally, I hope your message wasn't really "Teledyne Confidential; Commercially Sensitive Business Data".


Joe

> On 27 Apr 2021, at 12:30, Modster, Anthony via Unbound-users <unbound-users at lists.nlnetlabs.nl> wrote:
> 
> Hello Eduardo
> 
> Using wireshark, look at traffic to 192.52.178.30, there is an ICMP message.
> 
> 
> Teledyne Confidential; Commercially Sensitive Business Data
> 
> -----Original Message-----
> From: Eduardo Schoedler <listas at esds.com.br> 
> Sent: Tuesday, April 27, 2021 8:25 AM
> To: Modster, Anthony <Anthony.Modster at Teledyne.com>
> Cc: unbound-users at lists.nlnetlabs.nl
> Subject: Re: ICMP
> 
> ---External Email---
> 
> Em seg., 26 de abr. de 2021 às 17:40, Modster, Anthony via Unbound-users <unbound-users at lists.nlnetlabs.nl> escreveu:
>> 
>> When using “unbound resolver” I noticed an ICMP message sent, why does unbound need to do this ?
> 
> What type of ICMP ?
> 
> Some ICMP messages are sent from the OS.
> 
> --
> Eduardo Schoedler
> <test-method-3-auto-zone.dat>

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