what does this ip address notation means
[::] indicate all ipv6 addresses. 4443 is a port number. So if a service is bound to
[::]:4443 it'll be listening to all ipv6 addresses available in your system. It's similar to listening
0.0.0.0 for ipv4.
Some services bind to all IPs available (including ipv4) while binding to
[::]. Strictly speaking
[::] indicates ipv6 only. As per ipv6 writing convention, one consecutive block of
0's in an ipv6 address can be replaced with
::. Considering ipv6 is 128 bits the address
0000:0000:0000:0000:0000:0000:0000:0000 in expanded hexadecimal form.