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what does this ip address notation means [::]:[4443].

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    [::]:[4443] looks like a typo. It should have said [::]:4443 – kasperd Dec 27 '17 at 22:25
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[::] 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 :: is 0000:0000:0000:0000:0000:0000:0000:0000 in expanded hexadecimal form.

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    s/one contentious block/a contiguous group/ or /a consecutive group/. v4 addresses are mapped into v6 (at ::ffff:0000:0000/96) so listening on :: can accept both v6 and v4 if the implementation chooses, usually called 'single-stack'; only 'dual-stack' implementations require separate listens on :: and 0.0.0.0 – dave_thompson_085 Dec 27 '17 at 12:17
  • so what you are saying is that 4443 is listening port for all ipv4 and ipv6 addresses. – captainchhala Dec 28 '17 at 5:01
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It's a bind designation to port 4443 of all interfaces that support IPv6. It is equivalent to [0000:0000:0000:0000:0000:0000:0000:0000]:4443.

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