Unable to capture bluetooth using tcpdump

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I’m trying to capture bluetooth paquets using tcpdump on Ubuntu 20.04.

I have two computers that are exactly the same model (some same bluetooth chipset) with Ubuntu 20.04; The difference is that one computer (OLD) has been installed a while ago with a lot of things and the other (NEW) is a new computer with a fresh install.

I’m using the command sudo tcpdump -vv -i bluetooth0.

  • On OLD, I’m able to capture packets without any issue
  • on NEW, I don’t see any packet :
0 packets captured
6268 packets received by filter
0 packets dropped by kernel
  • I installed Wireshark on NEW and made sure that the user belonged to the groups “dialout” and “wireshark”.
  • The versions of tcpdump and libpcap are the same on both computers
  • I tried using Wireshark graphically to capture packets: it worked fine on OLD but not on NEW (no packets captures)
  • lsmod | grep bluetooth returns the same on both computers:
bluetooth             688128  41 btrtl,btintel,btbcm,bnep,btusb,rfcomm
ecdh_generic           16384  2 bluetooth

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