title: How come I have never seen an LTE sniffing tool on uplink?
body: <p>I am trying to find whether it is possible to sniff LTE traffics.</p>
  
  <p>However, I only found online about behaving as a fake base station (eNodeB) so devices will be forced to connect to you. Then you get info about other devices.</p>
  
  <p>But I never find a completely passive sniffing tool.</p>
  
  <p>There are downlink sniffing tool where you act as a benign user and search for basestation/cell signals. For example, openLTE and srsLTE.</p>
  
  <p>But how come there is no such a tool to sniff traffic on the uplink (from user device to basestation)? Or there is one that I couldn't find?</p>
  
  <p>Can some please explain this? I understand basic LTE frame structures and how they talk to the basestation.</p>
  
  <p>Thanks ahead.</p>