Server error while running "roscore".

edit

when I run roscore this error occurs. version:-ROS Kinetic UBUNTU 16.04LTS

melvin@melvin-HP-Notebook:~$ roscore
... logging to /home/melvin/.ros/log/d1cb9254-1ab8-11e8-b6a6-441ca8984d6d/roslaunch-melvin-HP-Notebook-4976.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

Unable to contact my own server at [http://192.168.43.40:39081/].
This usually means that the network is not configured properly.

A common cause is that the machine cannot ping itself.  Please check
for errors by running:

    ping 192.168.43.40

For more tips, please see

    http://www.ros.org/wiki/ROS/NetworkSetup

The traceback for the exception was written to the log file

export | grep -i ros gives output as

melvin@melvin-HP-Notebook:~$ ping 192.168.43.40
PING 192.168.43.40 (192.168.43.40) 56(84) bytes of data.
^Z
[1]+  Stopped                 ping 192.168.43.40
melvin@melvin-HP-Notebook:~$ export | grep -i ros
declare -x CMAKE_PREFIX_PATH="/opt/ros/kinetic"
declare -x LD_LIBRARY_PATH="/usr/local/cuda-8.0/lib64:/usr/local/lib:/opt/ros/kinetic/lib:/opt/ros/kinetic/lib/x86_64-linux-gnu"
declare -x OLDPWD="/home/melvin/ros"
declare -x PATH="/usr/local/cuda-8.0/bin:/opt/ros/kinetic/bin:/home/melvin/bin:/home/melvin/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin"
declare -x PKG_CONFIG_PATH="/opt/ros/kinetic/lib/pkgconfig:/opt/ros/kinetic/lib/x86_64-linux-gnu/pkgconfig"
declare -x PYTHONPATH="/opt/ros/kinetic/lib/python2.7/dist-packages"
declare -x ROSLISP_PACKAGE_DIRECTORIES=""
declare -x ROS_DISTRO="kinetic"
declare -x ROS_ETC_DIR="/opt/ros/kinetic/etc/ros"
declare -x ROS_IP="192.168.43.40"
declare -x ROS_MASTER_URI="http://localhost:11311"
declare -x ROS_PACKAGE_PATH="/opt/ros/kinetic/share"
declare -x ROS_ROOT="/opt/ros/kinetic/share/ros"
declare -x TURTLEBOT_GAZEBO_MAP_FILE="/opt/ros/kinetic/share/turtlebot_gazebo/maps/playground.yaml"
declare -x TURTLEBOT_GAZEBO_WORLD_FILE="/opt/ros/kinetic/share/turtlebot_gazebo/worlds/playground.world"
declare -x TURTLEBOT_MAP_FILE="/opt/ros/kinetic/share/turtlebot_navigation/maps/willow-2010-02-18-0.10.yaml"
melvin@melvin-HP-Notebook:~$