Broadcast Boradcast Socket sendto Error errno:101 Network is unreachable

Keywords: Linux broadcast 255.255.255.255

SendTo Error:network is unreachable

Full network broadcast

Scene:

Today, when you debug a broadcast on Linux network programming, when you send a broadcast packet to a port on 255.255.255.255, SendTo returns-1 for the wrong reason:

SendTo Error:network is unreachable.

Workaround:

1. Programming Solution:

struct sockaddr_in localaddr;

Execute SOCKFD = Socket (af_inet, SOCK_DGRAM, 0); Add the following instruction after

SetSockOpt (SOCKFD, Sol_socket, So_broadcast, &sock_flag, sizeof (Sock_flag));

Bzero (&localaddr, sizeof (LOCALADDR));
localaddr.sin_family = af_inet;
Inet_pton (Af_inet, "192.168.1.125", &localaddr.sin_addr); 192.168.1.125 is the address of a local network card
Localaddr.sin_port = htons (12345);
Bind (SOCKFD, (SA *) &localaddr, sizeof (LOCALADDR));

2. Directive Solution:

Oute add-net 255.255.255.255 netmask 255.255.255.255 dev eth0 metric 1

Or

Route add-host 255.255.255.255 Dev eth0