<p><code>[::]</code> is IPv6's version of localhost (<code>0.0.0.0</code>).</p>

CC BY-SA 3.0
2015-10-26T09:36:43.460Z
`[::]` or `[::0]` is 'unspecified', equivalent to v4 `INADDR_ANY = 0.0.0.0`; `[::1]` is the equivalent of `INADDR_LOOPBACK = 127.0.0.1`. See https://en.wikipedia.org/wiki/IPv6_address#Special_addresses
dave_thompson_085
CC BY-SA 3.0
2015-10-26T12:03:40.917Z
@dave_thompson_085 thanks for the correction. `[::]:0` must then mean 0.0.0.0, port 0.
Geremia
CC BY-SA 3.0
2015-10-23T06:11:16.623Z
2015-10-26T12:03:10.493Z
2015-10-26T12:03:10.493Z
Geremia
<p>I am trying to run and connect multiple nodes on a single machine, i.e different nodes using different ports. I am having trouble in connecting the nodes and making them talk to each other. While debugging, I inserted a <code>LogPrintf("%s\n",addr)</code> in the while loop of <code>ThreadOpenConnections()</code> in <code>net.cpp</code> file.</p>

<p>The output in the debug.log file is always <code>[::]:0</code>. What does this address mean ? Is it for localhost representation or something else ? </p>

<bitcoind><connection><fallback-nodes><network>
What is [::]:0 address in bitcoin debug.log?
bawejakunal
# What is [::]:0 address in bitcoin debug.log?

(Asked by: username_0 on 2015-10-23)

I am trying to run and connect multiple nodes on a single machine, i.e different nodes using different ports. I am having trouble in connecting the nodes and making them talk to each other. While debugging, I inserted a `LogPrintf("%s\n",addr)` in the while loop of `ThreadOpenConnections()` in `net.cpp` file.

The output in the debug.log file is always `[::]:0`. What does this address mean ? Is it for localhost representation or something else ?

**Tags:** bitcoind, connection, fallback-nodes, network


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## 1 answers

### Answer by username_1 on 2015-10-23. Score: 1 | Accepted answer

`[::]` is IPv6's version of localhost (`0.0.0.0`).

> **Comments:**
> **username_2**: `[::]` or `[::0]` is 'unspecified', equivalent to v4 `INADDR_ANY = 0.0.0.0`; `[::1]` is the equivalent of `INADDR_LOOPBACK = 127.0.0.1`. See https://en.wikipedia.org/wiki/IPv6_address#Special_addresses  
> **username_1**: @username_2 thanks for the correction. `[::]:0` must then mean 0.0.0.0, port 0.  

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