View Full Version : [ubuntu] Not able to get multicast working

September 1st, 2010, 10:42 PM
I have several multicast data feeds that I'm trying to connect to using a minimal server install of Ubuntu as a VM on a VMWare ESXi server.

I have another VM on the same server running Solaris that can connect with no issues to the incoming multicast stream. All I had to do on the Solaris machine was run:

route -p add -iface
snoop -r -d e1000g2 udp | grep 225. (or grep 224.)
in order to see the incoming data

On the Ubuntu server VM I tried doing the same thing and making it persistent by adding the following to /etc/network/interfaces:

post-up route add -net gw dev eth1
also tried
post-up route add -net dev eth1

Result of netstat -rnv
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface U 0 0 0 eth1 U 0 0 0 eth0 UG 0 0 0 eth1 UG 0 0 0 eth0

The only difference when I tried the two different entries was the gateway flag disappearing and the gateway going to
I rebooted after each attempt.

Still not able to see any multicast data on that interface using

tcpdump -v -i eth1

or using wireshark for that interface.

/etc/network/interfaces File:
# The loopback network interface
auto lo eth0 eth1
iface lo inet loopback

# The primary network interface
iface eth0 inet static
dns-search nstb.act.faa.gov
# dns-* options are implemented by the resolvconf package, if installed

iface eth1 inet static
post-up route add -net gw dev eth1

All the multicast data comes in on eth1.
Any help would be appreciated!

October 9th, 2010, 06:31 AM
I'm currently playing with IPTV and multicast and found you need to disable the reverse packet filter by

echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter
echo 0 > /proc/sys/net/ipv4/conf/ethX/rp_filter

where ethX is the interface you want to receive on. Not sure if you need to do both all and ethX but I had to in order to get VLC and mythtv to see anything.
You can change the default boot up values in /etc/sysctl.conf