ENUM NFT_RT_KEYS(9)

💅 enum nft_rt_keys — the routing keys rundown

okay so this is from the Kernel API Manual (that's the manual name, hi 👋) and it's genuinely one of the cuter little enums in nf_tables land — it's the routing expression's key list, aka the lil menu of things you can ask the kernel about a packet's route. bestie, it's giving "short but iconic." 💖

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✨ NAME ✨

enum nft_rt_keys — the nf_tables routing expression keys. that's it. that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

like, literally this, no cap:

enum nft_rt_keys {
    NFT_RT_CLASSID ,
    NFT_RT_NEXTHOP4 ,
    NFT_RT_NEXTHOP6 ,
    NFT_RT_TCPMSS ,
    NFT_RT_XFRM ,
    __NFT_RT_MAX

};

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🌸 Constants 🌸

okay so here's the whole cast, main character energy each and every one:

• NFT_RT_CLASSID — the realm value of the packet's route, and bestie it's literally spelled out for us: skb->dst->tclassid. the way that thing has its own vibe tag 🏷️
• NFT_RT_NEXTHOP4 — routing nexthop for IPv4. the classic. the OG. 🫶
• NFT_RT_NEXTHOP6 — routing nexthop for IPv6. same energy, more colons. 🌈
• NFT_RT_TCPMSS — fetches the current path tcp mss. lowkey obsessed with this one 🍓
• NFT_RT_XFRM — a boolean, and the docs are so real for this: skb->dst->xfrm != NULL. it's giving "just check if it exists" 💀
• __NFT_RT_MAX — -- undescribed -- 🙈 like the manpage itself said "no thoughts, head empty" about this one. zero description, zero notes, just vibes and a double-underscore name. respect ✨

ngl, __NFT_RT_MAX is not me being lazy, that's literally all the source material says about it. no invented lore here, that's a promise. 💜

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👑 SEE ALSO 👑

the whole found family — and I mean the whole family, every single one of them, no skipping, we stan completeness:

Kernel file ./include/uapi/linux/netfilter/nf_tables.h enum nft_registers(9), enum nft_verdicts(9), enum nf_tables_msg_types(9), enum nft_list_attributes(9), enum nft_hook_attributes(9), enum nft_table_flags(9), enum nft_table_attributes(9), enum nft_chain_attributes(9), enum nft_rule_attributes(9), enum nft_rule_compat_flags(9), enum nft_rule_compat_attributes(9), enum nft_set_flags(9), enum nft_set_policies(9), enum nft_set_desc_attributes(9), enum nft_set_field_attributes(9), enum nft_set_attributes(9), enum nft_set_elem_flags(9), enum nft_set_elem_attributes(9), enum nft_set_elem_list_attributes(9), enum nft_data_types(9), enum nft_data_attributes(9), enum nft_verdict_attributes(9), enum nft_expr_attributes(9), enum nft_immediate_attributes(9), enum nft_bitwise_ops(9), enum nft_bitwise_attributes(9), enum nft_byteorder_ops(9), enum nft_byteorder_attributes(9), enum nft_cmp_ops(9), enum nft_cmp_attributes(9), enum nft_range_ops(9), enum nft_range_attributes(9), enum nft_lookup_attributes(9), enum nft_dynset_attributes(9), enum nft_payload_bases(9), enum nft_payload_csum_types(9), enum nft_payload_attributes(9), enum nft_exthdr_op(9), enum nft_exthdr_attributes(9), enum nft_meta_keys(9), enum nft_hash_types(9), enum nft_hash_attributes(9), enum nft_meta_attributes(9), enum nft_rt_attributes(9), enum nft_socket_attributes(9), enum nft_ct_keys(9), enum nft_ct_attributes(9), enum nft_offload_attributes(9), enum nft_limit_attributes(9), enum nft_connlimit_attributes(9), enum nft_counter_attributes(9), enum nft_last_attributes(9), enum nft_log_attributes(9), enum nft_log_level(9), enum nft_queue_attributes(9), enum nft_quota_attributes(9), enum nft_secmark_attributes(9), enum nft_reject_types(9), enum nft_reject_inet_code(9), enum nft_reject_attributes(9), enum nft_nat_types(9), enum nft_nat_attributes(9), enum nft_tproxy_attributes(9), enum nft_masq_attributes(9), enum nft_redir_attributes(9), enum nft_dup_attributes(9), enum nft_fwd_attributes(9), enum nft_objref_attributes(9), enum nft_gen_attributes(9), enum nft_object_attributes(9), enum nft_flowtable_flags(9), enum nft_flowtable_attributes(9), enum nft_flowtable_hook_attributes(9), enum nft_osf_attributes(9), enum nft_synproxy_attributes(9), enum nft_devices_attributes(9), enum nft_trace_attributes(9), enum nft_ng_attributes(9)

like… that's a lot of friends and I love that for them 💖

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and that's the whole page, bestie 🫶 this cutie lives in ./include/uapi/linux/netfilter and the date on it is October 2026 — slay, see you in the future ✨👑💅