$ gatttool -b 84:DD:20:E2:41:92 -I [ ][84:DD:20:E2:41:92][LE]> connect [CON][84:DD:20:E2:41:92][LE]> char-read-hnd 0x32 [CON][84:DD:20:E2:41:92][LE]> Characteristic value/descriptor read failed: Attribute requires authentication before read/write HCI sniffer - Bluetooth packet analyzer ver 2.5 device: hci0 snap_len: 1500 filter: 0xffffffffffffffff < HCI Command: LE Create Connection (0x08|0x000d) plen 25 bdaddr 84:DD:20:E2:41:92 type 0 interval 96 window 48 initiator_filter 0 own_bdaddr_type 0 min_interval 40 max_interval 56 latency 0 supervision_to 42 min_ce 0 max_ce 0 > HCI Event: Command Status (0x0f) plen 4 LE Create Connection (0x08|0x000d) status 0x00 ncmd 1 > HCI Event: LE Meta Event (0x3e) plen 19 LE Connection Complete status 0x00 handle 64, role master bdaddr 84:DD:20:E2:41:92 (Public) > ACL data: handle 64 flags 0x02 dlen 16 L2CAP(d): cid 0x0005 len 12 [psm 0] < ACL data: handle 64 flags 0x00 dlen 10 L2CAP(d): cid 0x0005 len 6 [psm 0] < HCI Command: LE Connection Update (0x08|0x0013) plen 14 > HCI Event: Command Status (0x0f) plen 4 LE Connection Update (0x08|0x0013) status 0x00 ncmd 1 > HCI Event: Number of Completed Packets (0x13) plen 5 handle 64 packets 1 < ACL data: handle 64 flags 0x00 dlen 7 ATT: Read req (0x0a) handle 0x0032 > ACL data: handle 64 flags 0x02 dlen 9 ATT: Error (0x01) Error: Insufficient authentication (5) Read req (0x0a) on handle 0x0032 > HCI Event: Number of Completed Packets (0x13) plen 5 handle 64 packets 1