STRUCT LANDLOCK_NET_PORT_ATTR(9)

💅 struct landlock_net_port_attr(9) — like, the network port definition one

okay so you're in the Kernel API Manual bestie, and we're talking about struct landlock_net_port_attr — literally the network port definition, that's the whole vibe ✨

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🌸 NAME 🌸

struct landlock_net_port_attr — network port definition. that's it, that's the girl 🎀

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✨ SYNOPSIS ✨

struct landlock_net_port_attr {
    __u64 allowed_access;
    __u64 port;
 };

she's small, she's cute, she has exactly two fields, no notes 💅

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🫶 Members 🫶

• allowed_access — a bitmask of the allowed network actions for a port (cf. Network flags_). so like, what's actually permitted on this port, encoded as bits 💖
• port — the network port, in host endianness. don't get weird with byte order, ok? 🙈

ok important note, do NOT skip this one: a port of 0 passed to :manpage:bind(2) will bind to an available port from the ephemeral port range. you can configure that range with the /proc/sys/net/ipv4/ip_local_port_range sysctl (also used for IPv6), and within that range, on a per-socket basis with setsockopt(IP_LOCAL_PORT_RANGE) 🔥

and second note, also lowkey essential: a Landlock rule with port 0 and the LANDLOCK_ACCESS_NET_BIND_TCP or LANDLOCK_ACCESS_NET_BIND_UDP right means that requesting to bind on port 0 is allowed, and it will automatically translate to binding on a kernel-assigned ephemeral port 👑 no cap, the kernel picks for you.

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⭐ Description ⭐

she's the argument of sys_landlock_add_rule. that's the whole description. iconic behaviour, honestly 🌈

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🦋 SEE ALSO 🦋

go read these next, i'm obsessed with all of them fr fr:

• Kernel file ./include/uapi/linux/landlock.h struct landlock_ruleset_attr(9)
• landlock_create_ruleset_flags(9)
• landlock_add_rule_flags(9)
• landlock_restrict_self_flags(9)
• enum landlock_rule_type(9)
• struct landlock_path_beneath_attr(9)
• fs_access(9)
• net_access(9)
• scope(9)

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💀 reminder bestie: everything above is exactly what the page says, i'm just louder about it.

and that's the page! coming to you from ./include/uapi/linux, dated October 2026, titled struct land...et_port_attr(9) (yes the truncation is real, we love her anyway) — mwah, bye 👑💖🧚