ENUM MPTCP_EVENT_TYPE(9)

💅 enum mptcp_event_type(9) — Kernel API Manual ✨

okay bestie, so this one's from the Kernel API Manual, and it's literally the master list of Netlink MPTCP event types. Netlink's out here sending vibes, and this enum is the group chat where every event announces itself. let's go 🫶

✨ NAME ✨

enum mptcp_event_type — the Netlink MPTCP event types. that's it, that's the whole name. iconic.

🌸 SYNOPSIS 🌸

here's the whole cast, no cuts, no skips:

enum mptcp_event_type {
    MPTCP_EVENT_UNSPEC ,
    MPTCP_EVENT_CREATED ,
    MPTCP_EVENT_ESTABLISHED ,
    MPTCP_EVENT_CLOSED ,
    MPTCP_EVENT_ANNOUNCED ,
    MPTCP_EVENT_REMOVED ,
    MPTCP_EVENT_SUB_ESTABLISHED ,
    MPTCP_EVENT_SUB_CLOSED ,
    MPTCP_EVENT_SUB_PRIORITY ,
    MPTCP_EVENT_LISTENER_CREATED ,
    MPTCP_EVENT_LISTENER_CLOSED

};

🧮 Constants 🧮

okay so now the lore for each one. no cap, these are all the members and their exact attributes 👑

• MPTCP_EVENT_UNSPEC — literally unused. a filler event. it's giving placeholder energy, lowkey just vibing in the enum doing nothing 💀
• MPTCP_EVENT_CREATED — a new MPTCP connection has been created!! this is the moment, bestie — it's the good time to allocate memory and send ADD_ADDR if needed. depending on the traffic-patterns it can take a long time until the MPTCP_EVENT_ESTABLISHED is sent, so don't be out here expecting it immediately, fr fr. Attributes: token, family, saddr4 | saddr6, daddr4 | daddr6, sport, dport, [server-side], [flags]. 🎀
• MPTCP_EVENT_ESTABLISHED — a MPTCP connection is established (which means it can start new subflows 🦋). Attributes: token, family, saddr4 | saddr6, daddr4 | daddr6, sport, dport, [server-side], [flags].
• MPTCP_EVENT_CLOSED — a MPTCP connection has stopped. and it only brings one attribute to the party: token. minimal queen 😭
• MPTCP_EVENT_ANNOUNCED — a new address has been announced by the peer. Attributes: token, rem_id, family, daddr4 | daddr6 [, dport].
• MPTCP_EVENT_REMOVED — an address has been lost by the peer. sad girl hours. Attributes: token, rem_id.
• MPTCP_EVENT_SUB_ESTABLISHED — a new subflow has been established (slay!), and 'error' should not be set. Attributes: token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport, dport, backup, if-idx [, error].
• MPTCP_EVENT_SUB_CLOSED — a subflow has been closed. an error (copy of sk_err) could be set if an error has been detected for this subflow 👀. Attributes: token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport, dport, backup, if-idx [, error].
• MPTCP_EVENT_SUB_PRIORITY — the priority of a subflow has changed. and like its sibling above, 'error' should not be set. Attributes: token, family, loc_id, rem_id, saddr4 | saddr6, daddr4 | daddr6, sport, dport, backup, if-idx [, error].
• MPTCP_EVENT_LISTENER_CREATED — a new PM listener is created 🌈. Attributes: family, sport, saddr4 | saddr6. (notice there's no token here, bestie — that's the whole point of a listener, it's out here before any connection exists 💅)
• MPTCP_EVENT_LISTENER_CLOSED — a PM listener is closed. Attributes: family, sport, saddr4 | saddr6. same trio, different mood 💜

lowkey important: MPTCP_EVENT_SUB_ESTABLISHED and MPTCP_EVENT_SUB_PRIORITY both say 'error' should not be set — like, that's the spec, don't be messy about it 🙈

🔮 SEE ALSO 🔮

• Kernel file ./include/uapi/linux/mptcp_pm.h — go read it, iykyk 📖

aaaand that's a wrap, bestie 🎀 this page lives in ./include/uapi/linux, dated October 2026, and it's the enum mptcp_event_type(9) entry 💖 mwah, go build something with subflows ✨🦋