STRUCT NFT_SET_DESC(9)

💅 struct nft_set_desc(9) — the Kernel API Manual glow-up 🎀

okay so real talk, this is a page from the Kernel API Manual all about struct nft_set_desc(9), and honestly? it's the blueprint page. it's the little struct that tells you what a netfilter set is made of. no cap. 🦋

---

✨ NAME ✨

struct nft_set_desc — description of set elements (yes, literally the description of set elements, she's not hiding anything 💁‍♀️)

---

🌸 SYNOPSIS 🌸

bestie, here's the whole struct, verbatim, don't touch a single character:

struct nft_set_desc {
    u32 ktype;
    unsigned int            klen;
    u32 dtype;
    unsigned int            dlen;
    u32 objtype;
    unsigned int            size;
    u32 policy;
    u32 gc_int;
    u64 timeout;
    u8 field_len[NFT_REG32_COUNT];
    u8 field_count;
    bool expr;
 };

---

👑 Members 👑

these are the fields, and each one ate, no notes 💅

• ktype — key type. the what kind of key of it all.
• klen — key length. how long the key is, obviously 🎀
• dtype — data type. the vibe of the data.
• dlen — data length. how much data we're talking.
• objtype — object type. the object's whole identity tbh.
• size — number of set elements. like, how many besties are in the set 🫶
• policy — set policy. the rules of the house.
• gc_int — garbage collector interval. how often the cleanup crew comes through 🧹
• timeout — element timeout. elements don't stay forever, they have a curfew ⏰
• field_len — length of each field in concatenation, bytes. yup, in bytes, keep it exact 📏
• field_count — number of concatenated fields in element. count 'em up.
• expr — set must support for expressions. not optional in the vibes department 🔥

---

🦋 SEE ALSO 🦋

so many icons in one list, i'm obsessed 😭 — kernel file ./include/net/netfilter/nf_tables.h, and then:

struct nft_verdict(9), struct nft_regs(9), struct nft_ctx(9), struct nft_userdata(9), struct nft_set_elem(9), enum nft_iter_type(9), enum nft_set_class(9), struct nft_set_estimate(9), struct nft_expr(9), struct nft_set_ops(9), struct nft_set_type(9), struct nft_set(9), struct nft_set_binding(9), enum nft_set_extensions(9), struct nft_set_ext_type(9), struct nft_set_ext_tmpl(9), struct nft_set_ext(9), struct nft_expr_type(9), struct nft_expr_ops(9), struct nft_rule(9), struct nft_chain_validate_state(9), struct nft_chain(9), struct nft_chain_type(9), struct nft_base_chain(9), struct nft_table(9), struct nft_object_hash_key(9), struct nft_object(9), struct nft_object_type(9), struct nft_object_ops(9), struct nft_flowtable(9), struct nft_traceinfo(9), struct nft_trans(9), struct nft_trans_hook(9), struct nft_trans_binding(9)

---

ok that's the whole page, go read the structs, i believe in you 💖

and that's a wrap, bestie 🎀 sign-off time: this iconic little number lives in ./include/net/netfilter, dated October 2026. periodt. 💅✨