Check out the sysctl? `net.ipv4.conf.all.mc_forwarding`


the other possible multicast parameters are


 # sysctl -a | grep igmp
 
 net.ipv4.igmp_max_memberships = 20
 
 
 
 # sysctl -a | grep mc
 
 net.ipv4.conf.pimreg.mc_forwarding = 1
 
 net.ipv4.conf.ipsec0.mc_forwarding = 0
 
 net.ipv4.conf.eth1.mc_forwarding = 1
 
 net.ipv4.conf.eth0.mc_forwarding = 1
 
 net.ipv4.conf.lo.mc_forwarding = 0
 
 net.ipv4.conf.default.mc_forwarding = 0
 
 net.ipv4.conf.all.mc_forwarding = 1
 
 net.ipv4.neigh.pimreg.mcast_solicit = 3
 
 net.ipv4.neigh.ipsec0.mcast_solicit = 0
 
 net.ipv4.neigh.eth1.mcast_solicit = 3
 
 net.ipv4.neigh.eth0.mcast_solicit = 3
 
 net.ipv4.neigh.lo.mcast_solicit = 3
 
 net.ipv4.neigh.default.mcast_solicit = 3
 
 
 
 # sysctl -a | grep pim
 
 net.ipv4.conf.pimreg.arp_filter = 0
 
 net.ipv4.conf.pimreg.tag = 0
 
 net.ipv4.conf.pimreg.log_martians = 0
 
 net.ipv4.conf.pimreg.bootp_relay = 0
 
 net.ipv4.conf.pimreg.medium_id = 0
 
 net.ipv4.conf.pimreg.proxy_arp = 0
 
 net.ipv4.conf.pimreg.accept_source_route = 1
 
 net.ipv4.conf.pimreg.send_redirects = 1
 
 net.ipv4.conf.pimreg.rp_filter = 0
 
 net.ipv4.conf.pimreg.shared_media = 1
 
 net.ipv4.conf.pimreg.secure_redirects = 1
 
 net.ipv4.conf.pimreg.accept_redirects = 1
 
 net.ipv4.conf.pimreg.mc_forwarding = 1
 
 net.ipv4.conf.pimreg.forwarding = 1
 
 net.ipv4.neigh.pimreg.locktime = 100
 
 net.ipv4.neigh.pimreg.proxy_delay = 80
 
 net.ipv4.neigh.pimreg.anycast_delay = 100
 
 net.ipv4.neigh.pimreg.proxy_qlen = 64
 
 net.ipv4.neigh.pimreg.unres_qlen = 3
 
 net.ipv4.neigh.pimreg.gc_stale_time = 60
 
 net.ipv4.neigh.pimreg.delay_first_probe_time = 5
 
 net.ipv4.neigh.pimreg.base_reachable_time = 30
 
 net.ipv4.neigh.pimreg.retrans_time = 100
 
 net.ipv4.neigh.pimreg.app_solicit = 0
 
 net.ipv4.neigh.pimreg.ucast_solicit = 3
 
 net.ipv4.neigh.pimreg.mcast_solicit = 3