HCSECD(8)

💙 HCSECD(8) — like, the system manager's manual but make it cute

okay bestie, so this is hcsecd from section 8 of the System Manager's Manual, and honestly? she's lowkey iconic. she's the one who remembers your Bluetooth devices so you don't have to re-pair like a peasant every single time. let's get into it 💅

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✨ NAME ✨

hcsecd — control link keys and PIN codes for Bluetooth devices 🦋

🌸 SYNOPSIS 🌸

hcsecd [-dh] -f configfile

💖 DESCRIPTION 💖

so the hcsecd daemon is literally the girlboss in charge of link keys and PIN codes for Bluetooth devices. she opens a raw HCI socket and just... listens. patiently. for Link_Key_Request, PIN_Code_Request and Link_Key_Notification HCI events. main character energy honestly 👑

the way it works: once a Link_Key_Request or PIN_Code_Request HCI event comes in, the daemon scans the configuration file looking for a matching entry. the remote device BD_ADDR is used as the key 🔑. if no matching entry was found, the default entry gets used instead. and if there's no default entry either? then it's assumed that no link key and no PIN code exists, periodt. for any given entry, the link key takes precedence over the PIN code — that's just the hierarchy, bestie. if a link key wasn't specified, the device must generate the link key from the PIN code.

if an entry was found and the link key (or PIN code) exists, then Link_Key_Request_Reply (or PIN_Code_Request_Reply) gets sent back to the device. otherwise? Link_Key_Request_Negative_Reply (or PIN_Code_Request_Negative_Reply) goes back to the device. sorry babes, no key for you 🙈

the hcsecd daemon also handles HCI Link_Key_Notification events and caches link keys created from the PIN codes in memory 🧠✨. and to preserve those link keys between restarts, she dumps the link keys for all entries into the /var/db/hcsecd.keys link keys file. if it exists, that link keys file gets processed by the daemon after she processes her main configuration file. the link keys file gets written every time the daemon shuts down gracefully 🎀. and yes — you can force the daemon to re-read her main configuration file and dump the link keys file by sending the HUP signal to the hcsecd process 🔥.

⚠️ okay important: the user is expected to not modify the link keys file by hand. hands off, bestie. fr fr.

the command line options are as follows 👇

🎀 OPTIONS 🎀

• -d — do not detach from the controlling terminal. she stays right there with you 🫶
• -f configfile — specify the name of the configuration file. the default is /etc/bluetooth/hcsecd.conf ✨
• -h — display usage message and exit. the classic "hi, bye" 💀

🦋 FILES 🦋

• /etc/bluetooth/hcsecd.conf
• /var/db/hcsecd.keys
• /var/run/hcsecd.pid

🌈 SEE ALSO 🌈

ng_btsocket(4), ng_hci(4), hcsecd.conf(5), hccontrol(8)

👑 AUTHORS 👑

Maksim Yevmenkin <m_evmenkin@yahoo.com>

💀 BUGS 💀

currently there is no way to select the link key or the PIN code based on which local device received the request. everything is based on the remote device BD_ADDR. and an interface for external helpers to obtain link keys and PIN codes is missing 😭 not me pointing out the gaps but like... the gaps are there.

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okay that's the whole page, bestie, you ate that 🍓✨ this was Debian's version, dated November 16, 2002 — and HCSECD(8) says slay, goodbye 💜🧚