Oracle Database EM 18 XE Available to Remote Clients

I found lot of posts about Oracle Database 18 XE. It's very interesting for me.  I didn't blog about how to install, because it's very easy for using rpm package and document very helpful.
I was interested in Enterprise Manager Database Express 18.4.0.0.0. How it looks like?
- Installing. I used CentOS7.

[student@centos-learning ~]$ sudo yum -y localinstall oracle-database*18c*
[student@centos-learning ~]$ sudo rpm -qa |grep oracle
oracle-database-preinstall-18c-1.0-1.el7.x86_64
oracle-database-xe-18c-1.0-1.x86_64

[student@centos-learning ~]$ sudo /etc/init.d/oracle-xe-18c configure
Specify a password to be used for database accounts. Oracle recommends that the password entered should be at least 8 characters in length, contain at least 1 uppercase character, 1 lower case character and 1 digit [0-9]. Note that the same password will be used for SYS, SYSTEM and PDBADMIN accounts:
The password you entered contains invalid characters. Enter password:
Confirm the password:
Configuring Oracle Listener.
Listener configuration succeeded.
Configuring Oracle Database XE.
Enter SYS user password:
*********
Enter SYSTEM user password:
********
Enter PDBADMIN User Password:
*********
Prepare for db operation
7% complete
Copying database files
29% complete
Creating and starting Oracle instance
30% complete
31% complete
34% complete
38% complete
41% complete
43% complete
Completing Database Creation
47% complete
50% complete
Creating Pluggable Databases
54% complete
71% complete
Executing Post Configuration Actions
93% complete
Running Custom Scripts
100% complete
Database creation complete. For details check the logfiles at:
 /opt/oracle/cfgtoollogs/dbca/XE.
Database Information:
Global Database Name:XE
System Identifier(SID):XE
Look at the log file "/opt/oracle/cfgtoollogs/dbca/XE/XE.log" for further details.
Connect to Oracle Database using one of the connect strings:
     Pluggable database: centos-learning.surachartopun.com/XEPDB1
     Multitenant container database: centos-learning.surachartopun.com
Use https://localhost:5500/em to access Oracle Enterprise Manager for Oracle Database XE
[student@centos-learning ~]$ netstat -ltn |grep 5500
tcp        0      0 127.0.0.1:5500          0.0.0.0:*               LISTEN

- As I didn't want to connect 127.0.0.1, I changed binding - "Making Oracle Database EM Express Available to Remote Clients"

SQL> !netstat -ltn |grep 5500
tcp        0      0 127.0.0.1:5500          0.0.0.0:*               LISTEN
SQL> !lsnrctl status | grep HTTP
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=127.0.0.1)(PORT=5500))(Security=(my_wallet_directory=/opt/oracle/product/18c/dbhomeXE/admin/XE/xdb_wallet))(Presentation=HTTP)(Session=RAW))
SQL>
SQL>
SQL> EXEC DBMS_XDB.SETLISTENERLOCALACCESS(FALSE);
PL/SQL procedure successfully completed.
SQL> !netstat -ltn |grep 5500
tcp        0      0 0.0.0.0:5500            0.0.0.0:*               LISTEN
SQL> !lsnrctl status | grep HTTP
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=centos-learning.surachartopun.com)(PORT=5500))(Security=(my_wallet_directory=/opt/oracle/admin/XE/xdb_wallet))(Presentation=HTTP)(Session=RAW))

- Browsed it - https://IP:5500/em

However, I got some error like "Connection with database failed. Database instance might be down."

- Checked alert log file and fixed.
Error: Global ports off in Root, do SetGlobalPortEnabled(TRUE) to enable.

bash-4.2$ tail -f alert_XE.log
2018-10-22T22:06:32.890217+07:00
Global ports off in Root, do SetGlobalPortEnabled(TRUE) to enable.
2018-10-22T22:06:38.489011+07:00
Global ports off in Root, do SetGlobalPortEnabled(TRUE) to enable.
2018-10-22T22:10:32.402822+07:00
Resize operation completed for file# 3, old size 501760K, new size 512000K
2018-10-22T22:15:55.791490+07:00
Global ports off in Root, do SetGlobalPortEnabled(TRUE) to enable.
2018-10-22T22:18:02.248906+07:00
Global ports off in Root, do SetGlobalPortEnabled(TRUE) to enable.

Setting the Global Port for EM Express to Manage a CDB and the PDBs. (It might not be the right solution, but I just wanted to see EM).

SQL> select dbms_xdb_config.getHttpsPort() from dual;
DBMS_XDB_CONFIG.GETHTTPSPORT()
------------------------------
                          5500
SQL> exec dbms_xdb_config.SetGlobalPortEnabled(TRUE)
PL/SQL procedure successfully completed.

- Login again.

It worked fine for now.

Reference: Installation Guide for Linux x86-64