Yes, it's possible to forestall this sort of thing in Safari by using ZoneAlarm (or some similar program), but it requires denying Safari the right to connect, then removing it from the list of permitted programs and then re-allowing it to connect. Aggravating.
The only instance I ever ran into from Safari making a connection from an earlier session was from one particular RSS feed. It basically did not happen with all the other RSS feeds. I have no idea what the deal was with that one particular feed. But, all that happened was a connection through port 80, which is the normal port for Safari to use. I mean, it’s sort of a non-starter issue, really. Not too much of anything except a curiosity (at least with me it was only that...). I wouldn’t consider that to be a problem.
Besides that, I can block any cookie that I want, if I choose to do so and I can turn off all cookies of I want to. So, it’s a matter of setting something up, if I’m really concerned about that. No other instance ever occured of Safari re-establishing anything from an earlier session.
As far as the ports that are normal for Safari to access, they would be port 80 and port 443. I have that currently set up to allow all the time for all IP addresses.
Now, if I were concerned about any other ports, I could simply have all other ports permanently blocked and never allow anything outside of those ports, but I don’t do that. I have it set up to allow and disallow, per session, as I determine — when the request comes up. I try to see what it is doing.
If I didn’t want to do that, it would be easy to disallow all others permanently and never have to think about it again. I could allow Safari to always connect on port 80 and 443, while disallowing all others — and I could leave it that way permanently. However, it appears that other web sites do want you to connect on other ports to various IP addresses. So, it appears to be a normal functionality of a web browser to do that — not something that is necessarily an adverse or illegal type of connection. All I’m saying is that if you’re that concerned about that — for any named web browser (and they’ll all do that) — then you can block the ports you don’t want used and do it for all IP addresses. Otherwise, you can let Safari work just like all the other web browsers work, accessing other IP addresses with other port numbers. I guess it’s just up to you as to how far you want to go with this thing. I’m just saying you can block it all or not. It’s just not a Safari thing that you’re referring to — it’s something that goes on with all web browsers.