You can use SMCRoute for this (yes, you need a separate daemon for managing multicast routes). SMCRoute can be used to set static multicast routes in the Linux kernel's multicast routing table, which is separate from the unicast routing table. Download the latest release and build it with:
tar xf smcroute-2.4.4.tar.gz
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
You can now run
make install to install SMCRoute to your system. However, I've chosen not to show that below, that's up to you. The reminder of my reply use paths relative to your build directory.
Now create a
smcroute.conf file with the following line:
mroute from eth0 source 192.168.1.2 group 188.8.131.52 to eth1
Start the SMCRoute daemon in the background like this:
sudo ./src/smcrouted -f smcroute.conf
You can then inspect the multicast routing table using one of:
sudo ./src/smcroutectl show routes
Make sure to check the TTL of the multicast stream from the server, it must be >1 to be routed by the kernel.
Also, you may want to look into changing the group of your server. The 224.0.0.* range is reserved for link-local multicast, which by definition should never be routed.