How do I interpret 'netstat -a' output

Question

Some things look strange to me:

• What is the distinction between 0.0.0.0, 127.0.0.1, and [::]?
• How should each part of the foreign address be read (part1:p

Answer 1

Send-Q is the amount of data sent by the application, but not yet acknowledged by the other side of the socket.

Recv-Q is the amount of data received from the NIC, but not yet consumed by the application.

Both of these queues reside in kernel memory. There are guides to help you tweak these kernel buffers, if you are so inclined. Although, you may find the default params do quite well.