IP Multicast 설정 여부 확인

$ ip maddr show
1:      lo
        inet  224.0.0.1
        inet6 ff02::1
2:      eth0
        link  01:00:5e:00:00:04
        link  01:00:5e:00:00:fb
        link  01:80:c2:00:00:03
        link  01:80:c2:00:00:00
        link  01:80:c2:00:00:0e
        link  33:33:00:00:02:02
        link  33:33:ff:73:d0:d8
        link  01:00:5e:00:00:01
        link  33:33:00:00:00:01
        inet  228.0.0.4 users 2
        inet  224.0.0.251
        inet  224.0.0.1
        inet6 ff02::202
        inet6 ff02::1:ff73:d0d8
        inet6 ff02::1
3:      eth1
        link  01:80:c2:00:00:03
        link  01:80:c2:00:00:00
        link  01:80:c2:00:00:0e
        link  33:33:00:00:00:01
        inet6 ff02::1

#ip maddr add MULTIADDR dev STRING
ip maddr add 224.0.0.1 dev eth1

#ip maddr del MULTIADDR dev STRING
ip maddr del 224.0.0.1 dev eth1

$ netstat -g
IPv6/IPv4 Group Memberships
Interface       RefCnt Group
--------------- ------ ---------------------
lo              1      all-systems.mcast.net
eth0            2      228.0.0.4
eth0            1      224.0.0.251
eth0            1      all-systems.mcast.net
lo              1      ff02::1
eth0            1      ff02::202
eth0            1      ff02::1:ff73:d0d8
eth0            1      ff02::1
eth1            1      ff02::1

$ cat /proc/net/igmp
Idx     Device    : Count Querier       Group    Users Timer    Reporter
1       lo        :     1      V3
                                010000E0     1 0:00000000               0
2       eth0      :     3      V3
                                040000E4     2 0:00000000               0
                                FB0000E0     1 0:00000000               0
                                010000E0     1 0:00000000               0

ifconfig eth0 |grep MULTICAST    
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

ifconfig eth0 multicast

ifconfig eth0 -multicast