Anonymiser.com might reveal your IP

From: Klaxon (klaxonat_private)
Date: Tue Nov 27 2001 - 06:55:11 PST

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      Hello, if this has been discussed in the past just tell me to sod off.
      While playing with proxy configurations for a machine at home I came 
     across a questionable behaviour from www.anonymiser.com. I stuck netcat
     on port 80 of this machine and than surfed back to it through Anonymiser.
     I know there's a transparent proxy on my ISP and apparently it attaches
     a "Client-ip: x.x.x.x" field to all http requests. What's fun is that
     Anonymiser happily copies this field to its own http request. Actually
     it will pass along any field sent with your request, which makes sense
     for "Accept-..." stuff but is obviously a bad ideia for anything else. 
    
    -------------------------------------
    [~]# nc -l -p 80
    
    GET / HTTP/1.0
    Host: foo.bar.com
    Accept: text/xml, application/xml, application/xhtml+xml, text/html;q=0.9, image/png, image/jpeg, image/gif;q=0.2, text/plain;q=0.8, text/css, */*;q=0.1
    Accept-Charset: iso-8859-1, utf-8;q=0.66, *;q=0.66
    Accept-Encoding: identity
    User-Agent: Mozilla/4.78 (TuringOS; Turing Machine; 0.0)
    Client-ip: X.X.X.X <------------ BOOM!
    Via: HTTP/1.1 proxy-02[XXXXXXX] (Traffic-Server/3.5.7 [XXXXXXXX])
    -------------------------------------
    
      So beware if you trust this service and there's an unknown proxy
     somewhere along the wire. Please note this experience was with
     Anonymiser.com's free service. I would like to know if anyone paying
     for it can confirm this.
      To try it: launch netcat on your port 80 (nc -l -p 80), telnet to
     www.anonymiser.com on port 80 and request your address:
    
    [~]$ telnet www.anonymiser.com 80
    Trying 168.143.112.10...
    Connected to www.anonymiser.com.
    Escape character is '^]'.
    GET http://your.ip.goes.here HTTP/1.0
    Foo-bar: it hurts
    
     Netcat should spit this:
    
    [~]# nc -l -p 80
    GET / HTTP/1.0
    Host: your.ip.goes.here
    Foo-bar: it hurts
    Connection: Keep-Alive
    
     If Foo-bar is there so can a Client-ip be.
    
    
    -- 
    EOF
    



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