Tcp6 in the output netstat

tcp6 simply means TCP protocol over IP v6.

tcp6 0 0 dmz.local.net:www 5.140.235.6%14631:49964 ESTABLISHED 21393/apache2

As from the netstat manual:

• tcp6: The protocol used. Here it is TCP over IPv6

• 0: The count of bytes not copied by the user program connected to this socket.

• 0: The count of bytes not acknowledged by the remote host. Local Address

• dmz.local.net:www: Address and port number of the local end of the socket. Unless the (-n) option is specified, the socket address is resolved to its canonical host name (FQDN), and the port number is translated into the corresponding service name.

• 5.140.235.6%14631:49964: Address and port number of the remote end of the socket.

• ESTABLISHED: The state of the socket. The state ESTABLISHED means the socket has an established connection.

• 21393/apache2: Slash-separated pair of the process id (PID) and process name of the process that owns the socket.

To sum up: your local apache2 process (pid= 21393), listening on the standard www port (80) has established a TCP (over IPv6) connection with the remote host 5.140.235.6%14631 on port 49964 (unresolved IPv6 address which is a link-local IPv6 address: an address that a computer assigns itself in order to facilitate local communications).

For more about IPv6:

• wikipedia IPv6 address notation
• this superuser thread about % in IPv6, that is Scope ID.