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Interesting, This method of fingerprinting bypasses "elite" anon proxies and gives away IP addresses and OS of the host. Google currently employs a number of t

by ukgent2 14y ago

Interesting, This method of fingerprinting bypasses "elite" anon proxies and gives away IP addresses and OS of the host. Google currently employs a number of tricks to get real IP addresses, you can run a connection via a proxy and 99% of websites you visit will only get the Proxy IP, Google has a way of getting IP from User_Agent (not sure how but I was building my own proxy last week and found this out). Will check the tor bundle later (as they are better configured) but I believe they will be harden against this, I dont know how I could make firefox in a default configuration stop leaking this information without cripping my install, anyideas?

afhof 14y ago
Aside from SNI (which the article mentions HAS to be submitted in plaintext) you might be able to randomize the supported ciphers. Just like faking the User Agent String, you might be able to randomly select a cipher suite equal to that of another browser (and that your browser supports as well).
- majke 14y ago
  Randomizing the ciphers is not a good idea. First, their order is significant - in theory the server should pick up the first it knows. Second, limiting supported ciphers inevitably may lead to incompatibility with some websites (as they may support only ciphers that were omitted).
chris_wot 14y ago
I'm curious to see how you tested this... the user-agent should only ever emit the browser (product) and a comment after this. It should never show the IP address of your machine! Were you doing the test on all browsers, or was it only Chrome? I'm curious as to what's going on here, because if Google have worked out how to get your IP address even when going through an SSL-capable proxy (not something I'd normally recommend, btw...) then I'd suggest they are sending something else over the wire. Mind you, if you have not disabled the X-Forward-For header on your proxy, then this may be how Google knows your originating IP address. You should be able to tell by running a packet trace between the proxy and the Google site you are accessing.
- derefr 14y ago
  Perhaps they're just probabilistically getting your IP address by clustering your user agent+browsing habits+etc against the set of IPs it's seen that cluster come from via AdSense embedding on other sites?
  - chris_wot 14y ago
    Without knowing the testing methodology of the original poster, it's hard to say for certain :-)
- ukgent2 14y ago
  My Approach is not very scintific I am very new to all this magic, I used the following websites http://www.google.co.uk/search?q=whats+my+ip http://www.google.co.uk/search?q=whats+my+ip this should bring up Googles view of your IP http://www.whatsmyip.org/ http://www.whatsmyip.org/ A classic view of IPaddy http://www.xhaus.com/headers http://www.xhaus.com/headers For a view of the headers currently being leaked by the browser Now I was setting up my proxy as I was doing these said tests so it was work in progress, First checked it all out with no changes to the headers. Then I started stripping the headers a few at a time to see the differences between the above websites and a few others. Now my IP changed as soon as I did an x-forward no change in the proxy configration. At this stage 99% of websites get the IP of the proxy, I was happy. however Google still was giving me my real IP. More header striping later and pinned it down to the user_agent. I know the user agent does not contain any IP information but I think google must be using it as part of the IDing of the broswer profile My main point today was that this SSL handshaking leaks lots of information that appears to be able to see real IP behind a proxy. The bad man in side of myself now wonders if I could knock up a script like https://p0f.popcnt.org/ https://p0f.popcnt.org/ that can see passed a proxy to get real IP addresse not that I would have anywhere interesting to put it, guess it is just the fun of doing it. Now I completely believe that my proxy could be just badly setup, so I also tested the p0f page on a number of elite proxies (public not private or paid) and the p0f page gives up the real IP every time. As i said, I will try the tor broswers to night (sidenote I only really test firefox because Chrome and IE lift proxy settings from the local system where as firefox is customizable Oh i used your header page, very nice http://my-addr.com/ip http://my-addr.com/ip (thank you), all headers are empty and it has the correct IP (proxyed) Sorry for spelling, :/ notepad lacks a spell:checker
aqme28 14y ago
"Google has a way of getting IP from User_Agent." Perhaps they've finally developed something along the lines of panopticlick (https://panopticlick.eff.org/ https://panopticlick.eff.org/) for tracking purposes.
peterwwillis 14y ago
You can't hide your IP address from the proxy, but assuming the proxy is not passing it along in an X-Forwarded-For or similar header, your browser will not pass the IP address along in the HTTP request (and never in the User Agent). You do need to disable all 3rd-party plugins and prevent cookies from being passed as they may separately reveal the IP address. This page will display the proxy headers which might be passing your IP, but more likely it's flash or java or something else sending it: http://my-addr.com/ip http://my-addr.com/ip

by ukgent2 14y ago

afhof 14y ago

Aside from SNI (which the article mentions HAS to be submitted in plaintext) you might be able to randomize the supported ciphers. Just like faking the User Agent String, you might be able to randomly select a cipher suite equal to that of another browser (and that your browser supports as well).

majke 14y ago
Randomizing the ciphers is not a good idea. First, their order is significant - in theory the server should pick up the first it knows. Second, limiting supported ciphers inevitably may lead to incompatibility with some websites (as they may support only ciphers that were omitted).

chris_wot 14y ago

I'm curious to see how you tested this... the user-agent should only ever emit the browser (product) and a comment after this. It should never show the IP address of your machine! Were you doing the test on all browsers, or was it only Chrome? I'm curious as to what's going on here, because if Google have worked out how to get your IP address even when going through an SSL-capable proxy (not something I'd normally recommend, btw...) then I'd suggest they are sending something else over the wire. Mind you, if you have not disabled the X-Forward-For header on your proxy, then this may be how Google knows your originating IP address. You should be able to tell by running a packet trace between the proxy and the Google site you are accessing.

derefr 14y ago
Perhaps they're just probabilistically getting your IP address by clustering your user agent+browsing habits+etc against the set of IPs it's seen that cluster come from via AdSense embedding on other sites?
- chris_wot 14y ago
  Without knowing the testing methodology of the original poster, it's hard to say for certain :-)
ukgent2 14y ago
My Approach is not very scintific I am very new to all this magic, I used the following websites http://www.google.co.uk/search?q=whats+my+ip http://www.google.co.uk/search?q=whats+my+ip this should bring up Googles view of your IP http://www.whatsmyip.org/ http://www.whatsmyip.org/ A classic view of IPaddy http://www.xhaus.com/headers http://www.xhaus.com/headers For a view of the headers currently being leaked by the browser Now I was setting up my proxy as I was doing these said tests so it was work in progress, First checked it all out with no changes to the headers. Then I started stripping the headers a few at a time to see the differences between the above websites and a few others. Now my IP changed as soon as I did an x-forward no change in the proxy configration. At this stage 99% of websites get the IP of the proxy, I was happy. however Google still was giving me my real IP. More header striping later and pinned it down to the user_agent. I know the user agent does not contain any IP information but I think google must be using it as part of the IDing of the broswer profile My main point today was that this SSL handshaking leaks lots of information that appears to be able to see real IP behind a proxy. The bad man in side of myself now wonders if I could knock up a script like https://p0f.popcnt.org/ https://p0f.popcnt.org/ that can see passed a proxy to get real IP addresse not that I would have anywhere interesting to put it, guess it is just the fun of doing it. Now I completely believe that my proxy could be just badly setup, so I also tested the p0f page on a number of elite proxies (public not private or paid) and the p0f page gives up the real IP every time. As i said, I will try the tor broswers to night (sidenote I only really test firefox because Chrome and IE lift proxy settings from the local system where as firefox is customizable Oh i used your header page, very nice http://my-addr.com/ip http://my-addr.com/ip (thank you), all headers are empty and it has the correct IP (proxyed) Sorry for spelling, :/ notepad lacks a spell:checker

aqme28 14y ago

"Google has a way of getting IP from User_Agent." Perhaps they've finally developed something along the lines of panopticlick (https://panopticlick.eff.org/ https://panopticlick.eff.org/) for tracking purposes.

peterwwillis 14y ago

You can't hide your IP address from the proxy, but assuming the proxy is not passing it along in an X-Forwarded-For or similar header, your browser will not pass the IP address along in the HTTP request (and never in the User Agent). You do need to disable all 3rd-party plugins and prevent cookies from being passed as they may separately reveal the IP address. This page will display the proxy headers which might be passing your IP, but more likely it's flash or java or something else sending it: http://my-addr.com/ip http://my-addr.com/ip