Simple script to setup your machine env to use a remote ROS master

use_robot.sh

#!/bin/bash

# Simple script to setup your machine env to use a remote ROS master
# example usage: use_robot.sh myrobot
# where myrobot is a resolvable hostname or an IP address

NORMAL=`tput sgr0 2> /dev/null`
GREEN=`tput setaf 2 2> /dev/null`

# get the IP of our device we'll use to conect to the host
TARGET_IP=$1
IP=`ip route get $TARGET_IP | head -n 1 | sed "s/.*src \(\S*\) .*/\1/"`

echo -e "${GREEN}using $1 ($TARGET_IP) via $IP${NORMAL}"

export ROS_MASTER_URI=http://$1:11311
export ROS_HOSTNAME=$IP
export ROS_IP=$IP

Troubleshooting

If after running this script on the ROS client things are not working as expected, here are some things to help debug further.

1. does rosnode list work? If not, then your client machine cannot reach the master by the name you specified.
2. otherwise does rostopic echo /rosout work? If not, then check which ROS_HOSTNAME the master uses. It is possible that it uses a hostname, X, different from what you are assuming and that hostname is not resolvable from the client. This is the most common issue I have seen. What's happening here is that the publisher of /rosout is registered with the ROS master using name X, and when the client subscribes to the topic, the master (via xmlrpc) tells the client to try and contact X for any messages on that topic. The client tries that but fails, because it cannot resolve X. So you need to either make sure all publishers (including the core itself) only use DNS resolvable names or use IPs. Or you can add the unresolvable names to the client's /etc/hosts (not recommended). To see which names ROS nodes used when registering with the master you can run rosnode list -a. You should be able to resolve all names listed there from any other machine connected to that master.

Thanks! My robot had a different hostname for all the nodes than expected. By adding the correct hostname and IP to a container's /etc/hosts , I was able to successfully listen to the nodes.