Linux Advanced Configuration detailed in Firewalld

IP masquerading and port forwarding

Firewalld supports two types of network address translation

• IP address camouflage (masquerade)

  • LAN can achieve multiple addresses share a single public Internet address
  • IP address masquerading only supports IPv4, IPv6 is not supported
  • Address masquerading is enabled by default external area
• Port Forwarding (Forward-port)
  • Also known as the destination address or port mapping
  • Through port forwarding, specify the IP address and port traffic to be forwarded to a different port on the same computer, or transferred to a different port on the computer

Configuring address masquerading

• Add address masquerading as a designated area

firewall-cmd [--permanent] [--zone= zone] --add-masquerade [--timeout seconds]
 //--timeout=seconds:在一段时间后自动删除该功能

• Delete address masquerading as a designated area

firewall-cmd [--permanent] [--zone= zone] --remove-masquerade

• Query whether to open a designated area address masquerading

firewall-cmd [--permanent] [--zone=zone] --query-masquerade

Port forwarding configuration

• Lists the port forwarding configuration

firewall-cmd [--permanent] [--zone=zone] --list-forward-ports

• Add port forwarding rules

firewall-cmd [--permanent] [--zone=zone] --add-forward-port=port=portid[-portid]:proto=protocol[:toport-portid[-portid]][:toaddr-address[/mask]][--timeout=seconds]

• Delete a port forwarding rule

firewall-cmd [--permanent] [--zone=zone] --remove-forward-port=port=portid[-portid]:proto=protocol[:toport=portid[-portid]][:toaddr=address[/mask]]

• Queries port forwarding rule

firewall-cmd [--permanent] [--zone=zone] --query-forward-port-port-portid[-portid]:proto=protocol[:toport-portid[-portid]][:toaddr=address[/mask]]

Firewalld direct rule

Direct rule (direct interface)

• It allows administrators to manually write iptables, ip6tables ebtables rules and inserted into Firewalld management area
• Achieved through firewall-cmd command --direct options
• In addition to the display means other than the insertion, priority matching rule directly

Custom rule chains

• Firewalld automatically configure the "rules of the area to create a custom rule chains
  • IN area name deny: refuse storage statements, in preference to "IN area name rules _allow" of
  • IN area name allow: storage permit statement

Allows TCP / 9000 inbound ports

irewall-cmd --direct --add-rule ipv4 filter IN work_ allow 0 -p tcp --dport 9000 j ACCEPT

• IN work_ allow: the chain rule matching work area
• 0: represents the highest priority rule, the rule is placed in front
• --Permanent option means you can increase the permanent configuration

Direct all inquiries rules

firewall-cmd --direct --get-all-rules
ipv4 filter IN_ work _allow 0 -p tcp --dport 9000 -j ACCEPT

• Can increase --permanent view option indicates that permanent configuration

Firewalld rich language rules

Rich language (rich language)

• Expressive configuration language, without knowing the syntax for iptables
• Essential for expression of allow / deny rules, configuration records (and for the auditd syslog), port forwarding, and rate limiting masquerading

rule [family="<rule family>"]
  [ source address="<address>" [invert "True"] ]
  [ destination address="<address>" [invert="True"] ]
  [ <element> ]
  [ log [prefix="<prefix text>"] [level="<log level>"] [limit value="rate/duration"] ]
  [ audit ]
  [ acceptlrejectldrop ]

Understand the rich command language rules

• firewall-cmd rich language processing rules commonly used options

Options	Explanation
-add-rich-rule= 'RULE'	RULE added to the designated area, if the area is not specified, or the default region
--remove-rich-rule= 'RULE'	RULE deleted from the designated area, if the area is not specified, or the default region
--query-rich-rule= 'RULE'	RULE whether the query has been added to the designated area, if the area is not specified, the default zone. <br/> rule exists, returns 0, otherwise 1
--list-rich-rules	All the rich rule specified area, if the area is not specified, the default zone

Configured rich display language rules

• firewall-cmd --list-all
• firewall-cmd --list-all-zones
• --list-rich-rules

Rich language specific syntax rules

• source、destination、 element、 service、 port、 protocol、icmp-block、masquerade、 forward-port、 log、 audit、acceptlreject|drop

Reject all the traffic from 192.168.8.101

firewall-cmd --permanent --zone=work --add-rich-rule='rule family=ipv4 source address=192.168.8.101/32 reject'

• ddress options to the source or destination, must be family = ipv4 | ipv6

Fan set to accept 192.168.1.0/24 subnet port of TCP traffic 8000-9000

firewall-cmd --permanent --one=work --add-rich-rule='rule family=ipv4 source address=192.168.1.0/24 port port=8000-9000 protocol=tcp accept'

Discard all icmp packets

firewall-cmd --permanent --add-rich-rule='rule protocol value=icmp drop'

To accept traffic from http 192.168.8.1 and log

firewall-cmd --add-rich-rule='rule family=ipv4 source address=192.168.8.1/32 service name="http" log level=notice prefix= "NEW HTTP”limit value "3/s" accept'

• 192.168.8.1 to access the http, and watch / var / log / messages

Apr 16 17:09:55 Server kernel: NEW HTTP IN=ens33 OUT=
MAC=00:0c:29:69:01:c4:00:50:56:c0:00:08:08:00 SRC=192.168.8.1 DST=192.168.8.131
LEN=52 TOS=0xOO PREC=0x00 TTL =64 ID=20582 DF PROTO=TCP SPT=65289 DPT=80
WINDOW=8192 RES=0x00 SYN URGP=0
Apr 16 17:09:55 Server kernel: NEW HTTP IN=ens33 OUT=
MAC=00:0c:29:69:01:c4:00:50:56:c0:00:08:08:00 SRC=192.168.8.1 DST=192.168.8.131
LEN=52 TOS=0x0O PREC=0x0O TTL =64 ID=20590 DF PROTO=TCP SPT=65291 DPT=80
WINDOW=8192 RES=0x00 SYN URGP=0
Apr 16 17:09:55 Server kernel: NEW HTTP IN=ens33 OUT=
MAC=00:0c:29:69:01:c4:00:50:56:c0:00:08:08:00 SRC=192.168.8.1 DST=192.168.8.131
LEN=52 TOS=0x0O PREC=0x0O TTL =64 ID=20602 DF PROTO=TCP SPT=65292 DPT=80
WINDOW=8192 RES=0x00 SYN URGP=0