If post contains external image - how to copy it to the /uploads/ and replace all external images as attachments automatically?

AFAIK, it can't readily be done, by intent and design... 

1 hour ago, KentT said:

AFAIK, it can't readily be done, by intent and design... 

can you explain?

Likely for copyright and ownership issues, photos and files from other sites are not treated the same as those uploaded to your site.  The most they've done is to allow IPS to fetch and cache them, and then serve them up from your server cache for performance reasons.  

To automatically retrieve them and incorporate them fully into your site would open IPS up to be accused of supporting copyright violations...

4 minutes ago, KentT said:

Likely for copyright and ownership issues

But if images 100% free?

I can write a hook. The decision is perhaps already made?

Just now, Slimer said:

But if images 100% free?

I can write a hook. The decision is perhaps already made?

Yes, and if you write and install that hook, you are liable in any lawsuit for copyright infringement, and not IPS...

inserting into post external image did not break any rules? Image is not yours, but you use it without demand.

2 hours ago, Slimer said:

If post contains external image - how to copy it to the /uploads/ and replace all external images as attachments automatically?

This is possible.  

ACP > System > Settings - Posting > Serve images from local server

11 minutes ago, Joel R said:

This is possible

No, imageproxy won't approach

1 hour ago, Slimer said:

inserting into post external image did not break any rules? Image is not yours, but you use it without demand.

That's the key word.  You are responsible for any copyright infringement...