Resolving port 5500 not free issue during Oracle 12c Release 2 Database Configuration Assistant installation on CentOS

Background

I am attempting to install Oracle 12c on CentOS 7 (deployed as a Hyper-V virtual machine) as outlined by this installation guide.

Problem

Everything with my installation goes well except for the Oracle Database Configuration Assistant.

The installation provides me with the following messages:

• ACTION: Specify a free port

• Action - Refer to the logs or contact Oracle Support Services.

Debuging Information and Actions Attempted

When I run a tail on the error log I get the following messages related to the installation:

INFO: ... GenericInternalPlugIn: getting configAssistantParmas.
INFO: ... GenericInternalPlugIn: checking secretArguments.
INFO: ... GenericInternalPlugIn: starting read loop.
INFO: Read: [FATAL] [DBT-06103] The port (5,500) is already in use.
INFO: [FATAL] [DBT-06103] The port (5,500) is already in use.
WARNING: Skipping line: [FATAL] [DBT-06103] The port (5,500) is already in use.
INFO: Read:    ACTION: Specify a free port.
INFO:    ACTION: Specify a free port.
WARNING: Skipping line:    ACTION: Specify a free port.
INFO: Completed Plugin named: Oracle Database Configuration Assistant

Running sudo netstat -anp | grep 550 returns the results below:

unix  3      [ ]         STREAM     CONNECTED     37299    5502/gnome-pty-help
unix  3      [ ]         STREAM     CONNECTED     37283    5501/gconfd-2
unix  3      [ ]         STREAM     CONNECTED     37287    5501/gconfd-2

To try and remedy the problem, prior to subsequent fresh installation attempts I commented out the following statements in my services file as displayed through running cat /etc/services | grep 550

```
new-rwho 550/tcp # new-who
new-rwho 550/udp # new-who
3m-image-lm 1550/tcp # Image Storage license manager 3M Company
3m-image-lm 1550/udp # Image Storage license manager 3M Company
ads 2550/tcp # ADS
ads 2550/udp

I encountered this exact error and found it was my mistake. Spent whole day for that.

Please, carefully observe your /etc/hostname and /etc/hosts.
In my case, "oem" was put in /etc/hosts and "eom" was in /etc/hostname.

StackExchange Database Administrators Q#167384, answer score: 14