在具有多个接口的服务器上接收多播(Linux) [英] receiving multicast on a server with multiple interfaces (linux)

问题描述

要在非默认NIC(dvb)上接收多播，请执行以下操作:

To receive a multicast on my not default NIC (dvb) I do the following:

• 打开一个套接字(AF_INET，SOCK_DGRAM)
• 在dvb接口上通过IP_ADD_MEMBERSHIP加入多播地址
• 绑定多播地址(请注意，常见的错误是绑定"0.0.0.0"，然后在该套接字上接收甚至不感兴趣的多播)和端口

这时，接收所需多播数据包的唯一方法是在路由表中添加一条规则，以通过dvb到达发件人所在的网络(另一个网络)，就像dvb需要回复多播一样发件人假设一种源发送方多播模式.有人知道发生了什么吗?这个问题使我很烦，因为原则上我不知道发件人的ip.

at this point the only way to receive the needed multicast packets is to add in the routing table a rule to reach the network where the sender is (another network) trough the dvb, as if the dvb needs to reply to the multicast sender; let say a sort of source sender multicast mode. Anyone knows what is going on? The problem is annoying to me because in principle I don't know the ip of sender.

推荐答案

您似乎被rp_filter反向路径过滤所困扰.如果数据包到达没有源地址路由的接口，则会丢弃数据包.

You appear to be being stung by rp_filter reverse-path filtering. This drops packets if they arrive on an interface that doesn't have a route for the source address.

您可以使用sysctl /proc/sys/net/ipv4/conf/<if>/rp_filter在每个接口上禁用它.

You can disable it on a per-interface basis with the sysctl /proc/sys/net/ipv4/conf/<if>/rp_filter.

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