title: netstat -g where is group IP defined
body: <p>Hello when I run netstat -g I see the following table. However, I just don't know what IP  all-system.mcast.net is mapped to? Where is this being defined? Is there a file in linux to set it up? Thanking you in advance</p>
  
  <pre><code>IPv6/IPv4 Group Memberships
  
  Interface       RefCnt Group
  --------------- ------ ---------------------
  lo              1      all-systems.mcast.net
  eth2            1      all-systems.mcast.net
  eth3            1      239.1.1.6
  eth3            1      239.1.1.3
  eth3            1      239.1.1.10
  eth3            1      239.1.1.14
  eth3            1      all-systems.mcast.net
  </code></pre>