The method 1, wherein establishing a session between the first control unit and the proxy server includes coupling through a second firewall, {HEAD ~ the proxy server} being inside {TAIL ~ the second firewall} 
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The method 1 , wherein establishing a session between the first control unit and the proxy server includes coupling through a second firewall , { HEAD ~ the proxy server } being inside { TAIL ~ the second firewall }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL