linux加入组播失败

What does "IP_ADD_MEMBERSHIP: No such device" mean?

It means that the tool is trying to use multicast but the network interface doesn't support it There are two likely causes:

·Your machine doesn't have multicast support enabled. For example, on Linux and FreeBSD it is possible to compile a kernel which doesn't support multicast.

·You don't have a route for multicast traffic. Some systems don't add this by default, and you need to run：

route add -net 224.0.0.0 netmask 224.0.0.0 eth0(or similar). If you wish to use RAT in unicast mode only, it is possible to add the multicast route on the loopback interface.

我一般都这样写：

mreq.imr_interface.s_addr = htonl(localIP)

先ping确认通不通，然后用traceroute IP

看看能通到哪，如果中间短了，可能是路由数据不完整。如果最后一跳短了，很可能是最后一跳缺乏回程路由或者访问的设备有防火墙保护，需要调整防火墙规则。

---