You want to get Hadoop's web UI to work. You have access to the back-end of a Linux server. How do you get the front-end of Hadoop (or hdfs) to work?
1. Deploy Hadoop. See this link for directions for any type of Linux.
2. Start the Hadoop services. For a single-node deployment of Hadoop use sudo find / -name start-dfs.sh to find it; use bash /path/to/start-dfs.sh to run it. For a multi-node deployment of Hadoop, log into the NameNode and use sudo find / -name start-all.sh to find it; use bash /path/to/start-all.sh to run it.
3. If it is a single-node cluster, find the external IP address of the server with curl http://icanhazip.com. If you have a multi-node Hadoop cluster, find the external IP address of the NameNode with curl http://icanhazip.com.
4. Open a web browser from a workstation and go to http://<externalIPaddress>:8088
If it does not work, remember that the back-end of the server running yarn should show "ResourceManager" in the results of a command like this: sudo jps # get ResourceManager to show first if there is a problem. To install jps, see this link.