IP_MULTICAST_LOOP(2const)

✨ IP_MULTICAST_LOOP ✨

okay bestie, welcome to the IP_MULTICAST_LOOP page 💖 this is one of the <const> pages — which is just a fancy way of saying "this is one option among many, and it lives inside the big IPPROTO_IP(2const) family." she's in section 2, she's about sockets, she's lowkey iconic. let's get into it 🦋

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🌸 NAME 🌸

IP_MULTICAST_LOOP — loop back sent multicast packets to local sockets

📚 LIBRARY 📚

Standard C library (libc, -lc) 💅

🎀 SYNOPSIS 🎀

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

int setsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_LOOP,
               const int *enable, sizeof(int));
int getsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_LOOP,
               int *enabled, sizeof(int));

💫 DESCRIPTION 💫

okay so picture this: you're sending multicast packets out into the world, and then — plot twist — should those same packets come right back around and land on the local sockets too? 👀

That's literally the whole job of IP_MULTICAST_LOOP. She sets or reads a boolean integer argument that decides whether sent multicast packets should be looped back to the local sockets. bool behavior, no cap 🎀

😭 ERRORS 😭

not me making you go read other pages, but fr fr:

• See IPPROTO_IP(2const).
• See setsockopt(2).
• See ip(7).

⏳ HISTORY ⏳

Linux 1.2. — she's been here since the beginning, a true main character since day one 👑

🫶 SEE ALSO 🫶

• IPPROTO_IP(2const)
• setsockopt(2)
• ip(7)

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and that's the whole vibe check, bestie 💜 go forth and loop those packets (or don't, your call, that's kinda the point) ✨

mwah 💅 this was brought to you by Linux man-pages 6.20, dated 2025-11-25, and the letter IP_MULTICAST_LOOP 🎀