Enabling Multicast on Ubuntu

Enabling Multicast on Ubuntu

For some unknown reason, Ubuntu doesn’t install allowing access to multicast from the shell, apps, etc.  You have to enable it by editing the /etc/sysctl.conf file:

sudo vi /etc/sysctl.conf

And add these parameters:

net.ipv4.conf.default.rp_filter = 0

net.ipv4.conf.all.rp_filter = 0

net.ipv4.icmp_echo_ignore_broadcasts = 0

HOWEVER - it looks like .default and .all don’t necessarily do the trick.  On some servers we’ve had to explicitly set it for specific NICs, e.g., .eth1. Instead of .default and .all

I had to set the rp_filter for eth1 explicitly:

sudo sysctl -w net.ipv4.conf.eth1.rp_filter=0

now it works

Then load the params to the running systems (or reboot):

sudo sysctl -p