Cannot access Tomcat from external IP address

Question

I installed tomcat on my virtual machine (on Azure) but failed to access it from an external IP address. I tried some methods I found on stack overflow, but they did not seem to work. The port forwarding tester also says Port 8080 is closed on [my_ip_address] . I did manage to access it from localhost:8080 or 127.0.0.1:8080 . I run curl 127.0.0.1:8080 and it returns the correct webpage. In addition, nginx is also able to access the website through the port.

The firewall is not running.

> sudo firewall-cmd --list-all
FirewallD is not running

Tomcat configuration file

I added address="0.0.0.0" , but it does not work in my case.

<?xml version='1.0' encoding='utf-8'?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
 -->
<Server port="8005" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <!-- Security listener. Documentation at /docs/config/listeners.html
  <Listener className="org.apache.catalina.security.SecurityListener" />
  -->
  <!--APR library loader. Documentation at /docs/apr.html -->
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->
  <Listener className="org.apache.catalina.core.JasperListener" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <!-- Global JNDI resources
       Documentation at /docs/jndi-resources-howto.html
  -->
  <GlobalNamingResources>
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources>

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" Note:  A "Service" is not itself a "Container",
       so you may not define subcomponents such as "Valves" at this level.
       Documentation at /docs/config/service.html
   -->
  <Service name="Catalina">

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->
    <!--
    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>
    -->


    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned. Documentation at :
         Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
         Java AJP  Connector: /docs/config/ajp.html
         APR (HTTP/AJP) Connector: /docs/apr.html
         Define a non-SSL HTTP/1.1 Connector on port 8080
    -->
    <Connector port="8080"
           address="0.0.0.0"
           useIPVHosts="true"
           protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" /> 
    <!-- A "Connector" using the shared thread pool-->
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    -->
    <!-- Define an SSL HTTP/1.1 Connector on port 8443
         This connector uses the BIO implementation that requires the JSSE
         style configuration. When using the APR/native implementation, the
         OpenSSL style configuration is required as described in the APR/native
         documentation -->
    <!--
    <Connector port="8443" protocol="org.apache.coyote.http11.Http11Protocol"
               maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" />
    -->

    <!-- Define an AJP 1.3 Connector on port 8009 -->
    <!--
    <Connector protocol="AJP/1.3"
               address="::1"
               port="8009"
               redirectPort="8443" />
    -->

    <!-- An Engine represents the entry point (within Catalina) that processes
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes them
         on to the appropriate Host (virtual host).
         Documentation at /docs/config/engine.html -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    -->
    <Engine name="Catalina" defaultHost="localhost">

      <!--For clustering, please take a look at documentation at:
          /docs/cluster-howto.html  (simple how to)
          /docs/config/cluster.html (reference documentation) -->
      <!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      -->

      <!-- Use the LockOutRealm to prevent attempts to guess user passwords
           via a brute-force attack -->
      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <!-- This Realm uses the UserDatabase configured in the global JNDI
             resources under the key "UserDatabase".  Any edits
             that are performed against this UserDatabase are immediately
             available for use by the Realm.  -->
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

      <Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">

        <!-- SingleSignOn valve, share authentication between web applications
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html
             Note: The pattern used is equivalent to using pattern="common" -->
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               resolveHosts="true" prefix="localhost_access_log." suffix=".txt"
           pattern="%h %l %u %t &quot;%r&quot; %s %b" />

      </Host>
    </Engine>
  </Service>
</Server>

Active Internet Connections

I managed to bind Apache Tomcat to IPv4 as suggested by confused genius, but it still did not work.

> netstat -ant
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:8005          0.0.0.0:*               LISTEN     
tcp        0      0 0.0.0.0:5355            0.0.0.0:*               LISTEN     
tcp        0     36 10.0.0.4:22             75.84.33.143:59788      ESTABLISHED
tcp        0      0 127.0.0.1:8080          127.0.0.1:57604         TIME_WAIT  
tcp        0      0 127.0.0.1:59724         127.0.0.1:8005          TIME_WAIT  
tcp        0      0 127.0.0.1:8080          127.0.0.1:57584         TIME_WAIT  
tcp        0      0 127.0.0.1:8080          127.0.0.1:57518         TIME_WAIT  
tcp        0      0 127.0.0.1:8080          127.0.0.1:57520         TIME_WAIT  
tcp        0      0 10.0.0.4:80             75.84.33.143:59952      ESTABLISHED
tcp        0      0 10.0.0.4:80             75.84.33.143:59953      ESTABLISHED
tcp6       0      0 :::22                   :::*                    LISTEN     
tcp6       0      0 :::5355                 :::*                    LISTEN 

Answer 1

From netstat -ant output , port 8080 is listenting only on tcp6 (ipv6) but not on tcp(ipv4).

tcp6       0      0 :::8080                 :::*                    LISTEN 

so it needs to be enabled for ipv4 as well in order to access it the host ip address check this link it might help

Answer 2

I found the solution. It actually has nothing to do with Tomcat. The problem lies in Azure: you need to explicitly allow the port to be accessible in Azure. Adding it to the firewall does not solve the problems. (You can add inbound port rule in Home/[VM]/Networking)