IP_MULTICAST_TTL2const
Time-to-live value of outgoing multicast packets
Usage
#include <netinet/in.h> /* Definition of IP* constants */ #include <sys/socket.h>
int setsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_TTL, const int *ttl, sizeof(int)); int getsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_TTL, int *ttl, sizeof(int));
Library
Standard C library (libc, -lc)
Overview
Set or read the time-to-live value of outgoing multicast packets for this socket.
The default is 1 which means that multicast packets don't leave the local network unless the user program explicitly requests it.
Errors
See IPPROTO_IP(2const). See setsockopt(2). See ip(7).
Caveats
It is very important for multicast packets to set the smallest TTL possible.