How should we represent an IPv6 address with port number in text?

Question

Under IPv4, the de facto standard notation 10.1.2.3:1234 is completely clear: it is an IP address with port number. This is understood in URL's for instance: http://10.1.2.3:1234/doc.xhtml.

If I have a sockaddr_ipv4 class in some code, its tostring method can return this colon notation and everything is cool.

In a fit of myopia, the designers for the IPv6 addresses numeric notation decided that the colon character was available for their use as a separator. As a result, a colon-delimited port number looks ambiguous on an IPv6 address.

How can we incorporate a port number into a printed representation of an IPv6 address-with-port? Is there some de facto standard way?

score 26 · Accepted Answer · answered Feb 29 '16 at 16:26

26

The common way of doing this is to enclose the IPv6 address in square brackets like this:

[2001:db8::1]:8080

This is what is being used in URLs for example:

http://[2001:db8::1]:8080/

answered Feb 29 '16 at 16:26

Sander Steffann

384

How should we represent an IPv6 address with port number in text?

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