Firewalld is a firewall management tool for Linux operating systems licensed under GNU General Public License 2.
Firewalld is the default firewall management tool in RHEL based Linux distros from version 7 onwards, where it replaces the legacy firewall management tool i.e. iptables. Firewalld is a dynamically managed firewall with support for network zones, IPv4, IPv6, ethernet bridges and IP sets.
In this article, we will explore the 3 ways to create a custom service in CentOS Firewall.
Table of Contents:
- System Specification
- 1) Create a Custom Firewalld Service using CLI
- 2) Create a Custom Firewalld Service from XML file
- 3) Create a Custom Firewalld Service from Definition File
System Specification:
Consider a scenario where we are running an Oracle Database 19c instance on CentOS 8 server.
Default Oracle Listener uses the service port 1521/tcp. We have also configured another Oracle Listener service that is using port 1522/tcp.
In short, we have two Oracle listeners running on ports 1521/tcp and 1522/tcp simultaneously.
Our objective is to create a custom firewalld service to control access from network to our Oracle Listener ports.
1) Create a Custom Firewalld Service using CLI:
In this method, we will create a custom firewalld service using firewall-cmd command.
Create a new service for Oracle Listener ports.
# firewall-cmd --permanent --new-service=oranet
success
Add long description of the service.
# firewall-cmd --permanent --service=oranet \ > --set-description="Oracle Listener Service" success
Add short description of the service.
# firewall-cmd --permanent --service=oranet \ > --set-short=oranet success
Add Oracle Listener service ports.
# firewall-cmd --permanent --service=oranet --add-port=1521/tcp
success
# firewall-cmd --permanent --service=oranet --add-port=1522/tcp
success
Reload firewalld configurations.
# firewall-cmd --reload
success
Display configurations of CentOS firewall.
# firewall-cmd --info-service=oranet
oranet
ports: 1521/tcp 1522/tcp
protocols:
source-ports:
modules:
destination:
We can add more settings to our service in similar way. You can refer to Firewalld Documentation for more details.
2) Create a Custom Firewalld Service from XML file:
In this method, we will define the firewalld service settings in an XML file and then use firewall-cmd command to create a custom service in our CentOS firewall.
# vi ~/oranet.xml
and add following XML code therein.
<?xml version="1.0" encoding="utf-8"?>
<service>
<short>oranet</short>
<description>Oracle Listener Service</description>
<port protocol="tcp" port="1521" />
<port protocol="tcp" port="1522" />
</service>
Now use firewall-cmd command to create CentOS firewall service.
# firewall-cmd --permanent --new-service-from-file=oranet.xml
success
Reload firewalld configurations and check oranet service.
# firewall-cmd --reload
success
# firewall-cmd --info-service=oranet
oranet
ports: 1521/tcp 1522/tcp
protocols:
source-ports:
modules:
destination:
3) Create a Custom Firewalld Service from Definition File:
This method is normally used by software packages during installation to create their respective firewalld services.
In this method, we create a custom service definition file in firewalld configuration directory.
# vi /etc/firewalld/services/oranet.xml
Add following XML code therein.
<?xml version="1.0" encoding="utf-8"?>
<service>
<short>oranet</short>
<description>Oracle Listener Service</description>
<port protocol="tcp" port="1521" />
<port protocol="tcp" port="1522" />
</service>
Reload firewalld configurations and check service oranet service.
# firewall-cmd --reload
success
# firewall-cmd --info-service=oranet
oranet
ports: 1521/tcp 1522/tcp
protocols:
source-ports:
modules:
destination:
We have explored all 3 ways to create a custom service in CentOS firewall.
Thank you, Sir. It's a great help.
ReplyDeleteYou're welcome.
Deletecual es el servicio por defecto que incluye el puerto 1521 y el 1522?
ReplyDeleteQ: What is the default service that includes port 1521 and 1522?
DeleteA: No, there is not default service defined for 1521 and 1522 (Oracle Listener Ports).
ty for your help :)
ReplyDeleteMy pleasure.
Delete