Re: Can a prefix be never routed on Internet but used only for source address in IP packets?

[Jonathan Kalbfeld via NANOG <nanog () lists nanog org>]

This happens unintentionally quite a bit with misconfigured NAT. You will see RFC 1918 source addresses in packets from 
time to time. I can't speak to the application or value of this, but I have seen this and done it accidentally on one 
occasion.
 

 
 
 
 
 
 
 
 
 
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>  
> On Aug 19, 2025 at 9:34 AM, Sriram, Kotikalapudi (Fed) via NANOG  <nanog () lists nanog org>  wrote:
>  
>  
>  Question: Can a prefix be never routed on the Internet but used only one-way for source address in IP packets? 
>
> That is. a user owns an IP prefix. They never advertise a route to it in BGP on the Internet. But they use the prefix 
> solely for source address in IP traffic from a source to a destination (sink). In this set up, the destination server 
> obviously cannot/doesn't return any acknowledgements etc. to the source. Anyone aware if there is any such known 
> application in use on the Internet - even if it is rare? Thanks.
>
> Sriram 
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