MQTT Socket error on client <unknown> : <p>I have setup MQTT on a Raspberry Pi and configured an Arduino Uno to the broker, but I am seeing the following entry in the /var/log/mosquitto/mosquitto.log file:</p>

<pre><code>New connection from 192.168.10.114 on port 1883.
Socket error on client &lt;unknown&gt;, disconnecting.
</code></pre>

<p>The Pi is setup with ETH0 wired to my local LAN and has an IP address of 192.168.1.50</p>

<p>There is also a WiFi AP setup on the Pi. The Arduino Uno connects via WiFi to send/receive MQTT messages. The WiFi AP has an IP address of 192.168.10.1 and provides DHCP leases via <code>dnsmasq</code>.</p>

<p>I have tried publishing and subscribing test on the local MQTT broker server (the Pi) and get the same error:</p>

<pre><code>Command:
mosquitto_sub -h 192.168.10.1 -t topic

mosquitto.log:
New connection from 192.168.10.1 on port 1883.
New client connected from 192.168.10.1 as mosqsub/1837-raspberryp (cl, k60).
Socket error on client &lt;unknown&gt;, disconnecting.
</code></pre>

<p>Here is /etc/mosquitto/mosquitto.conf:</p>

<pre><code>pid_file /var/run/mosquitto.pid

persistence true
log_dest file /var/log/mosquitto/mosquitto.log

allow_anonymous true

include_dir /etc/mosquitto/conf.d
</code></pre>

<p>sudo service mosquitto stop
sudo service mosquitto start:</p>

<pre><code>mosquitto version 1.4.8 terminating
mosquitto version 1.4.8 (build date Sun, 14 Feb 2016 15:06:55 +0000) starting
Config loaded from /etc/mosquitto/mosquitto.conf.
Opening ipv4 listen socket on port 1883.
Opening ipv6 listen socket on port 1883.
</code></pre>

<p>There might be an issue in my interfaces configuration. Here is /etc/network/interfaces:</p>

<pre><code>source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

iface eth0 inet manual

auto wlan0
allow-hotplug wlan0
iface wlan0 inet static
    address 192.168.10.1
    netmask 255.255.255.0
</code></pre>

<p>Can anyone point me on where the socket error is coming from on MQTT?</p>
