As of Centos7 the default firewall application has changed from iptables to firewalld. FirewallD provides dynamic filterinc versus static ones in iptables. You can read more about details of the features included at Fedora project page here and or on their official homepage here.
This page will help me to unlearn the iptables and remember the firewalld commands.
Get Initial information
- Get the status of firewalld
firewall-cmd --state
- Reload the firewall without loosing state information:
firewall-cmd --reload
- Get a list of all supported zones
firewall-cmd --get-zones
- Get a list of all supported services
firewall-cmd --get-services
- Get a list of all supported icmptypes
firewall-cmd --get-icmptypes
- List all zones with the enabled features.
firewall-cmd --list-all-zones
- Print zone <zone> with the enabled features. If zone is omitted, the default zone will be used.
firewall-cmd [--zone=<zone>] --list-all
- Get the default zone set for network connections
firewall-cmd --get-default-zone
- Set the default zone
firewall-cmd --set-default-zone=<zone>
All interfaces that are located in the default zone will be pushed in the new default zone, that defines the limitations for new external initiated connection attempts. Active connections are not affected.
- Get active zones
firewall-cmd --get-active-zones
- Get zone related to an interface
firewall-cmd --get-zone-of-interface=<interface>
Update the basic rules
This prints the zone name, if the interface is part of a zone
- Add an interface to a zone
firewall-cmd [--zone=<zone>] --add-interface=<interface>
Add an interface to a zone, if it was not in a zone before. If the zone options is omitted, the default zone will be used. The interfaces are reapplied after reloads.
- Change the zone an interface belongs to
firewall-cmd [--zone=<zone>] --change-interface=<interface>
This is similar to the –add-interface options, but pushes the interface in the new zone even if it was in another zone before.
- Remove an interface from a zone
firewall-cmd [--zone=<zone>] --remove-interface=<interface>
- Query if an interface is in a zone
firewall-cmd [--zone=<zone>] --query-interface=<interface>
Returns if the interface is in the zone. There is no output.
- List the enabled services in a zone
firewall-cmd [ --zone=<zone> ] --list-services
- Enable panic mode to block all network traffic in case of emergency
firewall-cmd --enable-panic
- Disable panic mode
firewall-cmd --disable-panic
- Query panic mode
firewall-cmd --query-panic
This returns the state of the panic mode, there is no output. To get a visual state use
firewall-cmd --query-panic && echo "On" || echo "Off"
Runtime zone handling
In the runtime mode the changes to zones are not permanent. The changes will be gone after reload or restart.
- Enable a service in a zone
firewall-cmd [--zone=<zone>] --add-service=<service> [--timeout=<seconds>]
This enables a service in a zone. If zone is not set, the default zone will be used. If timeout is set, the service will only be enabled for the amount of seconds in the zone. If the service is already active, there will be no warning message.
- Example: Enable ipp-client service for 60 seconds in the home zone:
firewall-cmd --zone=home --add-service=ipp-client --timeout=60
- Example: Enable the http service in the default zone:
firewall-cmd --add-service=http
- Disable a service in a zone
firewall-cmd [--zone=<zone>] --remove-service=<service>
This disables a service in a zone. If zone is not set, the default zone will be used.
- Example: Disable http service in the home zone:
firewall-cmd --zone=home --remove-service=http
The service will be disabled in the zone. If the service is not enabled in the zone, there will be an warning message.
- Query if a service is enabled in a zone
firewall-cmd [--zone=<zone>] --query-service=<service>
This returns 1 if the service is enabled in the zone, otherwise 0. There is no output.
- Enable a port and protocol combination in a zone
firewall-cmd [--zone=<zone>] --add-port=<port>[-<port>]/<protocol> [--timeout=<seconds>]
This enables a port and protocol combination. The port can be a single port or a port range -. The protocol can be either tcp or udp.
- Disable a port and protocol combination in a zone
firewall-cmd [--zone=<zone>] --remove-port=<port>[-<port>]/<protocol>
- Query if a port and protocol combination in enabled in a zone
firewall-cmd [--zone=<zone>] --query-port=<port>[-<port>]/<protocol>
This command returns if it is enabled, there is no output.
Masquerading
This is used to hide internal addresses behind a public IP or port.
- Enable masquerading in a zone
firewall-cmd [--zone=<zone>] --add-masquerade
This enables masquerading for the zone. The addresses of a private network are mapped to and hidden behind a public IP address. This is a form of address translation and mostly used in routers. Masquerading is IPv4 only because of kernel limitations.
- Disable masquerading in a zone
firewall-cmd [--zone=<zone>] --remove-masquerade
- Query masquerading in a zone
firewall-cmd [--zone=<zone>] --query-masquerade
This command returns if it is enabled, there is no output.
- Enable ICMP blocks in a zone
firewall-cmd [--zone=<zone>] --add-icmp-block=<icmptype>
This enabled the block of a selected Internet Control Message Protocol (ICMP) message. ICMP messages are either information requests or created as a reply to information requests or in error conditions.
- Disable ICMP blocks in a zone
firewall-cmd [--zone=<zone>] --remove-icmp-block=<icmptype>
- Query ICMP blocks in a zone
firewall-cmd [--zone=<zone>] --query-icmp-block=<icmptype>
This command returns if it is enabled, there is no output.
- Example: Block echo-reply messages in the public zone:
firewall-cmd --zone=public --add-icmp-block=echo-reply
- Enable port forwarding or port mapping in a zone
firewall-cmd [--zone=<zone>] --add-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
The port is either mapped to the same port on another host or to another port on the same host or to another port on another host. The port can be a singe port <port> or a port range <port>-<port>. The protocol is either tcp or udp. toport is either port or a port range -. toaddr is an IPv4 address. Port forwarding is IPv4 only because of kernel limitations.
- Disable port forwarding or port mapping in a zone
firewall-cmd [--zone=<zone>] --remove-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
- Query port forwarding or port mapping in a zone
firewall-cmd [--zone=<zone>] --query-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
This command returns if it is enabled, there is no output.
- Example: Forward ssh to host 127.0.0.2 in the home zone
firewall-cmd --zone=home --add-forward-port=port=22:proto=tcp:toaddr=127.0.0.2
Permanent zone handling
The permanent options are not affecting runtime directly. These options are only available after a reload or restart. To have runtime and permanent setting, you need to supply both. The –permanent option needs to be the first option for all permanent calls.
- Get a list of supported permanent services
firewall-cmd --permanent --get-services
- Get a list of supported permanent icmptypes
firewall-cmd --permanent --get-icmptypes
- Get a list of supported permanent zones
firewall-cmd --permanent --get-zones
- Enable a service in a zone
firewall-cmd --permanent [--zone=<zone>] --add-service=<service>
This enables the service in the zone permanently. If the zone option is omitted, the default zone is used.
- Disable a service in a zone
firewall-cmd --permanent [--zone=<zone>] --remove-service=<service>
- Query if a service is enabled in a zone
firewall-cmd --permanent [--zone=<zone>] --query-service=<service>
This command returns if it is enabled, there is no output.
- Example: Enable service ipp-client permanently in the home zone
firewall-cmd --permanent --zone=home --add-service=ipp-client
- Enable a port and protocol combination permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --add-port=<port>[-<port>]/<protocol>
- Disable a port and protocol combination permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --remove-port=<port>[-<port>]/<protocol>
- Query if a port and protocol combination is enabled permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --query-port=<port>[-<port>]/<protocol>
This command returns if it is enabled, there is no output.
- Example: Enable port 443/tcp for https permanently in the home zone
firewall-cmd --permanent --zone=home --add-port=443/tcp
- Enable masquerading permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --add-masquerade
This enables masquerading for the zone. The addresses of a private network are mapped to and hidden behind a public IP address. This is a form of address translation and mostly used in routers. Masquerading is IPv4 only because of kernel limitations.
- Disable masquerading permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --remove-masquerade
- Query masquerading permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --query-masquerade
This command returns if it is enabled, there is no output.
- Enable ICMP blocks permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --add-icmp-block=<icmptype>
This enabled the block of a selected Internet Control Message Protocol (ICMP) message. ICMP messages are either information requests or created as a reply to information requests or in error conditions.
- Disable ICMP blocks permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --remove-icmp-block=<icmptype>
- Query ICMP blocks permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --query-icmp-block=<icmptype>
This command returns if it is enabled, there is no output.
- Example: Block echo-reply messages in the public zone:
firewall-cmd --permanent --zone=public --add-icmp-block=echo-reply
- Enable port forwarding or port mapping permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --add-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
The port is either mapped to the same port on another host or to another port on the same host or to another port on another host. The port can be a singe port <port> or a port range <port>-<port>. The protocol is either tcp or udp. toport is either port or a port range -. toaddr is an IPv4 address. Port forwarding is IPv4 only because of kernel limitations.
- Disable port forwarding or port mapping permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --remove-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
- Query port forwarding or port mapping permanently in a zone
firewall-cmd --permanent [--zone=<zone>] --query-forward-port=port=<port>[-<port>]:proto=<protocol> { :toport=<port>[-<port>] | :toaddr=<address> | :toport=<port>[-<port>]:toaddr=<address> }
This command returns if it is enabled, there is no output.
- Example: Forward ssh to host 127.0.0.2 in the home zone
firewall-cmd --permanent --zone=home --add-forward-port=port=22:proto=tcp:toaddr=127.0.0.2
Direct options
The direct options give a more direct access to the firewall. These options require user to know basic iptables concepts, i.e. table (filter/mangle/nat/…), chain (INPUT/OUTPUT/FORWARD/…), commands (-A/-D/-I/…), parameters (-p/-s/-d/-j/…) and targets (ACCEPT/DROP/REJECT/…). Direct options should be used only as a last resort when it’s not possible to use for example –add-service=service or –add-rich-rule=’rule’. The first argument of each option has to be ipv4 or ipv6 or eb. With ipv4 it will be for IPv4 (iptables(8)), with ipv6 for IPv6 (ip6tables(8)) and with eb for ethernet bridges (ebtables(8)).
- Pass a command through to the firewall. <args> can be all iptables, ip6tables and ebtables command line arguments
firewall-cmd --direct --passthrough { ipv4 | ipv6 | eb } <args>
- Add a new chain <chain> to a table <table>.
firewall-cmd [--permanent] --direct --add-chain { ipv4 | ipv6 | eb } <table> <chain>
- Remove a chain with name <chain> from table <table>.
firewall-cmd [--permanent] --direct --remove-chain { ipv4 | ipv6 | eb } <table> <chain>
- Query if a chain with name <chain> exists in table <table>. Returns 0 if true, 1 otherwise.
firewall-cmd [--permanent] --direct --query-chain { ipv4 | ipv6 | eb } <table> <chain>
This command returns if it is enabled, there is no output.
- Get all chains added to table <table> as a space separated list.
firewall-cmd [--permanent] --direct --get-chains { ipv4 | ipv6 | eb } <table>
- Add a rule with the arguments <args> to chain <chain> in table <table> with priority <priority>.
firewall-cmd [--permanent] --direct --add-rule { ipv4 | ipv6 | eb } <table> <chain> <priority> <args>
- Remove a rule with the arguments <args> from chain <chain> in table <table>.
firewall-cmd [--permanent] --direct --remove-rule { ipv4 | ipv6 | eb } <table> <chain> <args>
- Query if a rule with the arguments <args> exists in chain <chain> in table <table>. Returns 0 if true, 1 otherwise.
firewall-cmd [--permanent] --direct --query-rule { ipv4 | ipv6 | eb } <table> <chain> <args>
This command returns if it is enabled, there is no output.
- Get all rules added to chain <chain> in table <table> as a newline separated list of arguments.
firewall-cmd [--permanent] --direct --get-rules { ipv4 | ipv6 | eb } <table> <chain>
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