Basic Operation of Firewalld Centos 7

This is the Basic Operation of Firewalld.

The definition of services is set to zones on Firewalld. To enable Firewall, assosiate a zone to a NIC with related commands.

1. To use Firewalld, start it

[root@dlp ~]# 

systemctl start firewalld 

[root@dlp ~]# 

systemctl enable firewalld 

2. By default, "public" zone is applied with a NIC and dhcpv6-client and ssh are allowed. When operating with "firewall-cmd" command, if you input the command without "--zone=***" specification, then, configuration is set to the default zone.

# display the default zone

[root@dlp ~]#

firewall-cmd --get-default-zone 

public

# display current settings

[root@dlp ~]# 

firewall-cmd --list-all 

public (default, active)
  interfaces: eno16777736
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
  

# display all zones defined by default

[root@dlp ~]# 

firewall-cmd --list-all-zones 

block
  interfaces:
  sources:
  services:
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
  .....
  .....
  

# display allowed services on a specific zone

[root@dlp ~]#

firewall-cmd --list-service --zone=external 

ssh

# change default zone

[root@dlp ~]# 

firewall-cmd --set-default-zone=external 

success

3. Display services defined by default.

[root@dlp ~]#

firewall-cmd --get-services 

amanda-client bacula bacula-client dhcp dhcpv6 dhcpv6-client dns ftp high-availability http https imaps ipp ipp-client ipsec kerberos kpasswd ldap ldaps libvirt libvirt-tls mdns mountd ms-wbt mysql nfs ntp openvpn pmcd pmproxy pmwebapi pmwebapis pop3s postgresql proxy-dhcp radius rpc-bind samba samba-client smtp ssh telnet tftp tftp-client transmission-client vnc-server wbem-https

# definition files are placed like follows

# if you'd like to add your original definition, add XML file on there

[root@dlp ~]# 

ls /usr/lib/firewalld/services 

amanda-client.xml      ipp-client.xml   mysql.xml       rpc-bind.xml
bacula-client.xml      ipp.xml          nfs.xml         samba-client.xml
bacula.xml             ipsec.xml        ntp.xml         samba.xml
dhcpv6-client.xml      kerberos.xml     openvpn.xml     smtp.xml
dhcpv6.xml             kpasswd.xml      pmcd.xml        ssh.xml
dhcp.xml               ldaps.xml        pmproxy.xml     telnet.xml
dns.xml                ldap.xml         pmwebapis.xml   tftp-client.xml
ftp.xml                libvirt-tls.xml  pmwebapi.xml    tftp.xml
high-availability.xml  libvirt.xml      pop3s.xml       transmission-client.xml
https.xml              mdns.xml         postgresql.xml  vnc-server.xml
http.xml               mountd.xml       proxy-dhcp.xml  wbem-https.xml
imaps.xml              ms-wbt.xml       radius.xml

4. Add or Remove allowed services.
The change will be back after rebooting the system. If you change settings permanently, add the "--permanent" option.

# for example, add http (the change will be valid at once)

[root@dlp ~]# 

firewall-cmd --add-service=http 
success
[root@dlp ~]# 

firewall-cmd --list-service 
dhcpv6-client http ssh




# for example, remove http

[root@dlp ~]# 

firewall-cmd --remove-service=http 
success
[root@dlp ~]# 

firewall-cmd --list-service 
dhcpv6-client ssh

# for example, add http permanently. (this permanent case, it's necessary to reload the Firewalld to enable the change)
[root@dlp ~]# 

firewall-cmd --add-service=http --permanent 
success
[root@dlp ~]# 

firewall-cmd --reload 
success
[root@dlp ~]# 

firewall-cmd --list-service 
dhcpv6-client http ssh

5. Add or remove allowed ports.

# for example, add TCP 465

[root@dlp ~]# 

firewall-cmd --add-port=465/tcp 
success
[root@dlp ~]# 

firewall-cmd --list-port 
465/tcp




# for example, remove TCP 465

[root@dlp ~]# 

firewall-cmd --remove-port=22/tcp 
success
[root@dlp ~]# 

firewall-cmd --list-port 
 

# for example, add TCP 465 permanently
[root@dlp ~]# 

firewall-cmd --add-port=465/tcp --permanent 
success
[root@dlp ~]# 

firewall-cmd --reload 
success
[root@dlp ~]# 

firewall-cmd --list-port 
465/tcp

6. Add or remove prohibited ICMP types.

# for example, add echo-request to prohibit it

[root@dlp ~]# 

firewall-cmd --add-icmp-block=echo-request 
success
[root@dlp ~]# 

firewall-cmd --list-icmp-blocks 
echo-request




# for example, remove echo-request

[root@dlp ~]# 

firewall-cmd --remove-icmp-block=echo-request 
success
[root@dlp ~]# 

firewall-cmd --list-icmp-blocks 
 

# display ICMP types
[root@dlp ~]# 

firewall-cmd --get-icmptypes 
destination-unreachable echo-reply echo-request parameter-problem redirect 
router-advertisement router-solicitation source-quench time-exceeded