:: is the unspecified address (
0:0:0:0:0:0:0:0), and it is only used in packets as the source address of a host that does not yet have an address and is trying to get an address assigned. What you see in the output means that a process is binding to port
8100 for all destination addresses in the host.
::1 is the loopback address (
0:0:0:0:0:0:0:1), and anything sent to that address will loop back inside the host. What you see means a process is binding to port
8100 on the loopback address, and that means anything sent to the loopback address on that port will go the that process.
Neither address can be seen as a destination address on a network outside of the host, and the unspecified address can only be used as a source address for a host that has not yet been assigned an address but is looking for an address. The loopback address should never be used as a source address on a network outside of the host.
RFC 4219, IP Version 6 Addressing Architecture explains how the two addresses are compressed in section 2.2. Text Representation of Addresses:
Due to some methods of allocating certain styles of IPv6 addresses,
it will be common for addresses to contain long strings of zero
bits. In order to make writing addresses containing zero bits
easier, a special syntax is available to compress the zeros. The use
of "::" indicates one or more groups of 16 bits of zeros. The "::"
can only appear once in an address. The "::" can also be used to
compress leading or trailing zeros in an address.
For example, the following addresses
2001:DB8:0:0:8:800:200C:417A a unicast address
FF01:0:0:0:0:0:0:101 a multicast address
0:0:0:0:0:0:0:1 the loopback address
0:0:0:0:0:0:0:0 the unspecified address
may be represented as
2001:DB8::8:800:200C:417A a unicast address
FF01::101 a multicast address
::1 the loopback address
:: the unspecified address
It further goes on to explain both the unspecified and loopback addresses:
2.5.2. The Unspecified Address
The address 0:0:0:0:0:0:0:0 is called the unspecified address. It must
never be assigned to any node. It indicates the absence of an
address. One example of its use is in the Source Address field of any
IPv6 packets sent by an initializing host before it has learned its
The unspecified address must not be used as the destination address of
IPv6 packets or in IPv6 Routing headers. An IPv6 packet with a source
address of unspecified must never be forwarded by an IPv6 router.
2.5.3. The Loopback Address
The unicast address 0:0:0:0:0:0:0:1 is called the loopback address. It
may be used by a node to send an IPv6 packet to itself. It must not
be assigned to any physical interface. It is treated as having
Link-Local scope, and may be thought of as the Link-Local unicast
address of a virtual interface (typically called the "loopback
interface") to an imaginary link that goes nowhere.
The loopback address must not be used as the source address in IPv6
packets that are sent outside of a single node. An IPv6 packet with a
destination address of loopback must never be sent outside of a single
node and must never be forwarded by an IPv6 router. A packet received
on an interface with a destination address of loopback must be