does as much as it can without going thru a real proxy Rated 4 out of 5 stars
Pretty cool idea. I think many of the reviewers didn't understand what it can and can't do. It can't change or completely hide your *real* IP address. Instead it makes it look like that's the IP of a *proxy* and that your own IP is the one being set in the headers by this add-on. I visited a number of the "what's my IP"-type sites and some reported such a proxy configuration but others apparently ignored these headers. If this add-on became very widely used then I'm sure it wouldn't "fool" much of *any* sites anymore.
I simply configure this this add-on to select from a range of thousands or hundreds of IP addresses that includes my own, which might look something like 184.108.40.206 - 220.127.116.11. These would be addresses that my ISP really uses in my local area, so it's theoretically plausible that I'm getting assigned these different IPs dynamically by my ISP! (Getting my ISP to really assign me a new dynamic IP frequently is not really so easy or I would do it).
That should solve most of the problems people have had because all of those IPs should show up as being in the same geographic area.
The add-on would be much better off-the-shelf if by default it chose a range of IP addresses based on the true IP like I describe above. Then there wouldn't be so many people who try it and it immediately starts breaking sites (and they give it a bad review).
It would be nice also if it could be set to change the IP less frequently (e.g. once per hour or day or per browser session) so it doesn't look suspicious to a site you're using that your IP keeps changing with every request while you're perhaps signed into that site or performing a multi-step transaction. Maybe that's what PayPal didn't like, but I suspect it had more to do with the IP changing to different countries and regions. I'd be suspicious too if I were PayPal and trying to prevent fraud.
I googled and didn't see as much about the CLIENT-IP header so I didn't set that one. I noticed that some sites specifically thought I was using a Proxy only when I set the VIA header (in addition to X-FORWARDED-FOR since I didn't try it without this header).
BTW, I am able to manually get my ISP to change my real IP address, but it requires logging into my home router's admin console and changing its MAC address, and then recycling the power on my cable modem so it sees a brand new MAC address and the DHCP server gives it a brand new dynamic IP. I'm certainly not going to do that every day nor probably even every week. If I were an ISP I would offer automatic IP-switching as a privacy feature, maybe even charging a dollar or two extra per month for it :-)
BTW, this add-on is in my collection "recommended security & privacy add-ons that are minimally-invasive" https://addons.mozilla.org/en-US/firefox/collections/dabruro/security/