Red Hat 7 with JBoss A-MQ 6.1: management console is not accessible - activemq

Question

We're having the same problem as this OP: JBoss ActiveMQ on Red Hat - Unable to access AMQ Web Console, however that post doesn't indicate how he solved the problem.
We're trying to evaluate JBoss A-MQ, and have installed RHEL 7 with A-MQ 6.1 according to their installation guide. Everything works locally, e.g. the sample producer/consumer tests succeed in the Verifying the Installation step.
However, we cannot access the management console, even after configuring the remote user. We did have to add a JAVA_OPTIONS entry to setenv to override the default IPv6 sockets, and netstat shows that the service is now listening on the tcp socket instead of tcp6:
File /opt/jboss-a-mq-6.1.0.redhat-379/bin/setenv now contains:
JAVA_OPTS="$JAVA_OPTS -Djava.net.preferIPv4Stack=true"
export JAVA_OPTS
# netstat -paunt | grep 8181
tcp 0 0 0.0.0.0:8181 0.0.0.0:* LISTEN 10698/java
We can ping the box from other systems, however attempting to open a telnet session on port 8181 times out. The management console URLs we've tried are:
http://172.16.100.110:8181/hawtio
http://172.16.100.110:8181
but neither work. What are we missing?
Here are entries from amq.log containing hawt, which seem like it is starting things up correctly:
$ grep hawt amq.log
2014-09-09 11:32:35,778 | INFO | FelixStartLevel | HttpServiceFactoryImpl | .internal.HttpServiceFactoryImpl 35 | 98 - org.ops4j.pax.web.pax-web-runtime - 3.0.6 | Binding bundle: [io.hawt.hawtio-web [146]] to http service
2014-09-09 11:32:35,860 | INFO | pool-10-thread-1 | ConfigManager | io.hawt.system.ConfigManager 32 | 146 - io.hawt.hawtio-web - 1.2.0.redhat-379 | Configuration will be discovered via system properties
2014-09-09 11:32:35,863 | INFO | pool-10-thread-1 | JmxTreeWatcher | io.hawt.jmx.JmxTreeWatcher 63 | 146 - io.hawt.hawtio-web - 1.2.0.redhat-379 | Welcome to hawtio 1.2-redhat-379 : http://hawt.io/ : Don't cha wish your console was hawt like me? ;-)
2014-09-09 11:32:35,865 | INFO | pool-10-thread-1 | UploadManager | io.hawt.jmx.UploadManager 40 | 146 - io.hawt.hawtio-web - 1.2.0.redhat-379 | Using file upload directory: /opt/jboss-a-mq-6.1.0.redhat-379/data/tmp/uploads
2014-09-09 11:32:35,868 | INFO | pool-10-thread-1 | AuthenticationFilter | io.hawt.web.AuthenticationFilter 84 | 146 - io.hawt.hawtio-web - 1.2.0.redhat-379 | Starting hawtio authentication filter, JAAS realm: "karaf" authorized role: "admin" role principal classes: ""
2014-09-09 11:32:35,965 | INFO | FelixStartLevel | HttpServiceFactoryImpl | .internal.HttpServiceFactoryImpl 35 | 98 - org.ops4j.pax.web.pax-web-runtime - 3.0.6 | Binding bundle: [io.hawt.hawtio-karaf-terminal [148]] to http service
2014-09-09 11:32:35,987 | INFO | pool-10-thread-2 | ConfigManager | io.hawt.system.ConfigManager 32 | 148 - io.hawt.hawtio-karaf-terminal - 1.2.0.redhat-379 | Configuration will be discovered via system properties
2014-09-09 11:32:35,988 | INFO | pool-10-thread-2 | AuthenticationFilter | io.hawt.web.AuthenticationFilter 84 | 148 - io.hawt.hawtio-karaf-terminal - 1.2.0.redhat-379 | Starting hawtio authentication filter, JAAS realm: "karaf" authorized role: "admin" role principal classes: ""
2014-09-09 11:32:35,996 | WARN | FelixStartLevel | ConfigFacade | io.hawt.config.ConfigFacade 23 | 149 - io.hawt.hawtio-maven-indexer - 1.2.0.redhat-379 | No ConfigFacade constructed yet so using default configuration for now
2014-09-09 11:32:36,015 | INFO | pool-10-thread-2 | LoginServlet | io.hawt.web.LoginServlet 55 | 148 - io.hawt.hawtio-karaf-terminal - 1.2.0.redhat-379 | hawtio login is using default HttpSession timeout
2014-09-09 11:32:36,128 | INFO | pool-10-thread-1 | hawtio-web - 146} | lipse.jetty.util.log.JavaUtilLog 75 | 90 - org.eclipse.jetty.aggregate.jetty-all-server - 8.1.14.v20131031 | jolokia-agent: No access restrictor found at classpath:/jolokia-access.xml, access to all MBeans is allowed
2014-09-09 11:32:36,191 | INFO | pool-10-thread-1 | LoginServlet | io.hawt.web.LoginServlet 55 | 146 - io.hawt.hawtio-web - 1.2.0.redhat-379 | hawtio login is using default HttpSession timeout
2014-09-09 11:32:39,227 | INFO | de startup timer | MavenIndexerFacade | maven.indexer.MavenIndexerFacade 98 | 149 - io.hawt.hawtio-maven-indexer - 1.2.0.redhat-379 | Storing maven index files in local directory: /opt/jboss-a-mq-6.1.0.redhat-379/data/mavenIndexer
2014-09-09 11:32:39,621 | INFO | de startup timer | MavenIndexerFacade | maven.indexer.MavenIndexerFacade 148 | 149 - io.hawt.hawtio-maven-indexer - 1.2.0.redhat-379 | Updating the maven indices. This may take a while, please be patient...
2014-09-09 11:32:39,852 | INFO | de startup timer | MavenIndexerFacade | maven.indexer.MavenIndexerFacade 185 | 149 - io.hawt.hawtio-maven-indexer - 1.2.0.redhat-379 | Completed updating 2 maven indices.

Answer 1

OMG, it was the firewall on the local server.
After spending the day scouring the web for ideas, trying to figure out what was wrong with my configuration, in desperation I finally thought I should try disabling the firewall and see what happens. So I shut it down with the command:
sudo service firewalld stop
and suddenly I could access the management console! I tried the default URL, and it worked:
http://172.16.100.110:8181
d'oh!