IPPROTO_IPV6(2const)

✨ IPPROTO_IPV6 ✨

okay so bestie, lemme put you on 💅 this is the page for IPPROTO_IPV6, aka the Linux IPv6 protocol socket options situation — it's a 2const page, so it's like the little sibling hanging off the section 2 corner of your man pages, iykyk. no cap, this is the one you want when you're out here tuning IPv6 sockets and need to know which knobs even exist.

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📚 LIBRARY

Standard C library — link it with -lc and you're golden 🫶

#include <netinet/in.h>  /* Definition of IP* constants */
#include <sys/socket.h>

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🎀 SYNOPSIS

here's the whole vibe, fr fr:

int setsockopt(int sockfd, IPPROTO_IPV6, int opt,
               const void val[size], size_t size);
int getsockopt(int sockfd, IPPROTO_IPV6, int opt,
               void val[size], size_t size);

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🌸 DESCRIPTION

so IPv6 has its own lil collection of protocol-specific socket options 🌈 you set them with setsockopt(2) and you read them back with getsockopt(2). the socket option level you pass for IPv6 is IPPROTO_IPV6 — that's literally the whole identity of this page.

and a lil note on booleans bestie: a boolean integer flag is zero when it's false, and anything else means true. that's it, that's the rule, no vibes beyond that 😌

the following socket options are supported 👇 obsessed with this list honestly:

• IPV6_ADDRFORM(2const)
• IPV6_ADD_MEMBERSHIP(2const)
• IPV6_DROP_MEMBERSHIP(2const)
• IPV6_MTU(2const)
• IPV6_MTU_DISCOVER(2const)
• IPV6_MULTICAST_HOPS(2const)
• IPV6_MULTICAST_IF(2const)
• IPV6_MULTICAST_LOOP(2const)
• IPV6_RECVPKTINFO(2const)
• IPV6_RTHDR(2const)
• IPV6_AUTHHDR(2const)
• IPV6_DSTOPTS(2const)
• IPV6_HOPOPTS(2const)
• IPV6_FLOWINFO(2const)
• IPV6_HOPLIMIT(2const)
• IPV6_RECVERR(2const)
• IPV6_ROUTER_ALERT(2const)
• IPV6_UNICAST_HOPS(2const)
• IPV6_V6ONLY(2const)

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💀 ERRORS

go check setsockopt(2), and also ipv6(7) — they got the deets.

• ENOPROTOOPT — opt is invalid. yeah that one's on you bestie, the option you asked for just isn't a thing 🙈

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👑 HISTORY

• IPPROTO_IPV6 — POSIX.1-2001. she's old, she's established, she's iconic.

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🔥 SEE ALSO

setsockopt(2), cmsg(3), ipv6(7)

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okay that's the whole page bestie, go forth and socket responsibly 🦋💖 this was Linux man-pages 6.20, dated 2026-01-05, and that's the IPPROTO_IPV6(2const) tea ☕ slay, periodt ✨