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From:   Axelle <aafortinet@gmail.com>
Date:   Tue, 9 Jul 2019 13:40:51 +0200
Message-ID: <CANKzOHD7JyDDv_3=HWH3CxD-F5uc2p37Lh9Zp9hVgFeN1uDNTQ@mail.gmail.com>
Subject: Connecting with security mode 1 level 3
To:     linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi list,

How do I connect to a BLE device using security mode 1 level 3 please?

With bluetoothctl, I do not see any way to do this. Instead, I
connected and then paired. It said success in both cases, but then one
of my write requests is failing with "Error: Insufficient
authentication (5)" which I assume means that I did not get to level
3.

I tried also with btgatt-client provided in bluez/tools. I specified
"high" (-s high) level but I get the same issue: error 5. I had a look
at the security mode with "get-security" and it told me I was using
level 1 :( I set it back to level 3, but actually that does not seem
to do anything, it remains at level 1 !

sudo ./btgatt-client --t random -s high -v -d MAC-ADDRESS
[GATT client]# write-value 0x0014 0xFF 0xFF...

[GATT client]# att: ATT op 0x12
[GATT client]# att: < 12 14 00 ff ff ff ff ff ff ff ff
[GATT client]# att: > 01 12 14 00 05
[GATT client]# att: ATT response received: 0x01
[GATT client]# att: Retrying operation 0xb0d160
...
[GATT client]# get-security
Security level: 1
[GATT client]# set-security 3
Setting security level 3 success
[GATT client]# get-security
Security level: 1

I am using Bluez 5.50 on a Linux Mint host.

Thanks,
Axelle