Connecting to a ros master without internet

edit

Your description:

name    ip            ros_master_uri             ros_ip
-------------------------------------------------------------
master  192.168.1.99  http://localhost:11311     -
slave   192.168.1.12  http://192.168.1.99:11311  192.168.1.99

if I understand your setup correctly, you are running a roscore instance on the master machine, and need the slave machine to connect to that.

I don't really understand why "with internet" it works, but ROS_IP should be set to the ip address of the machine itself ("sets the declared network address of a ROS Node", see Node Environment Variables - ROS_IP/ROS_HOSTNAME). It should not point to master in your case.

The use case for ROS_IP is one where you have no working DNS on your network, and it forces the middleware to use only addresses, not hostnames, when interacting with the rest of your graph. If "without internet" actually means "without a working DNS server", then setting ROS_IP correctly should allow your setup to work.

PS: be sure to not also have ROS_HOSTNAME set, as that will cause ROS_IP to be ignored.

I got similar problem like you. You could check here if it could help you : ros-communication-between-both-machines-slow-in-router-with-out-internet-connection

Network Configuration in ROS

Robot IP = 192.168.yyyy

$ gedit .bashrc then put those lines

   export ROS_MASTER_URI=http://localhost:11311
    export ROS_HOSTNAME=192.168.yyyy
    export ROS_IP=192.168.yyyy

WorkStation IP=192.168.xxxx

$ gedit .bashrc then put those lines

export ROS_HOSTNAME=192.168.xxxx
export ROS_IP=192.168.xxxx
export  ROS_MASTER_URI=http://192.168.yyyy:11311