ROS remote master: can see topics but no data

edit

I'm using this and it works for me:

RemoteROS.sh

export ROS_HOSTNAME=/bin/hostname -I

export ROS_MASTER_URI="http://$1:11311"

echo Using ROS MASTER at $ROS_MASTER_URI from $ROS_HOSTNAME

ping -c 1 $1

rostopic list

export LIBGL_ALWAYS_SOFTWARE=1

The lack of data means that your client can see the ROS master, but cannot connect to the topics on the remote machine. The cause is that the services on the remote machine are not accepting remote connections, only local. This is determined by the ROS_IP variable.

So, to use ROS over network, you need do two two things:

On the machine running roscore, you need to make sure that your services listen on any port. When no port is set, localhost (127.0.0.1) is used. So, you should select the IP of your machine on the internal network, or listen on any interface:

export ROS_IP=0.0.0.0 # Listen on any interface

OR

export ROS_IP=192.168.1.1 # Listen on 192.168.1.1

On the machine running roscore, you needn't worry about ROS_MASTER_URI or ROS_HOSTNAME.

On the client machine, not running roscore, there's two things you need to do. First, you need to make sure that ROS nodes are able to connect to the master by specifying ROS_MASTER_URI:

export ROS_MASTER_URI=192.168.1.1:11311

Second, you need to make sure that nodes running on the remote machine can also access topics published on the local machine, by setting ROS_IP to something different than 127.0.0.1, so:

export ROS_IP=0.0.0.0 # To listen on any interface

I solved my problem by adding both machines' hostname to /etc/hosts. refer to https://husarion.com/tutorials/ros-tu...

Details:

You can use roswtf to see what's happening. For me I got this error on my client machine:

ERROR: Unknown host [robot-desktop] for node [***]

where "robot-desktop" is the hostname of the master machine. If this ERROR occurs, you need to add the hostname of both machines to /etc/hosts like this:

X.X.X.X master-hostname

X.X.X.X client-hostname

You can run hostname in terminal to see the hostname of the machine.

Disable Firewall worked for me

Use below cmd to disable Firewall (refer)

$ sudo ufw disable

Hello. I solved this problem. I simple used roswtf and realized that it can't find hostname. Something trying to get access to rosmaster by hostnames from my local machine. So i added this host to '/etc/hosts'.