netstat -g where is group IP defined

Question

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

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

Answer 1

The "all-systems.mcast.net" and similar addresses are reserved for IP multicasting and are registered with IANA. They cannot be changed.

In your case all-systems.mcast.net is 224.0.0.1.

You can find these assignments http://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml

Answer 2

If you want to see only the IP addresses in this output, not the names, run netstat -ng.