A while ago openSUSE switched to firewalld as a fronte-end for iptables. Tumbleweed was first in 2018, so I wrote a reminder: On my research list: migrate from OpenSuSE SuSEfirewall2 to firewalld « The Wiert Corner – irregular stream of stuff.
The core concept of firewalld is zones, which some people find hard to understand: [Archive.is/WayBack] Firewalld on Leap 15 – why is it so complicated ? : openSUSE.
Another concept is interfaces and how they bind to zones. [Wayback] Masquerading and Firewalls | Security Guide | openSUSE Leap 15.2 shows more of that.
The final concept is services that bind one or more aspects (like ports or addresses) to a service name [Wayback] Documentation – Manual Pages – firewalld.service | firewalld.
Other interesting bits of information:
Below are some examples on what I learned, especially finding details about active interfaces and the zones they are bound to.
All of them are based on:
- the
xargs shell trick (I known you can do some of them without the trick, but I try to use common patterns in my solution so I do not have to remember which boundary case fails
- the
echo -n trick to skip the newline output
- the [WayBack]
firewall-cmd options (which kind of care commands)
--get-active-zones:
Print currently active zones altogether with interfaces and sources used in these zones. Active zones are zones, that have a binding to an interface or source. The output format is:
zone1
interfaces: interface1 interface2 ..
sources: source1 ..
zone2
interfaces: interface3 ..
zone3
sources: source2 ..
If there are no interfaces or sources bound to the zone, the corresponding line will be omitted.
--list-interfaces:
List interfaces that are bound to zone zone as a space separated list. If zone is omitted, default zone will be used.
--get-zone-of-interface=<zone>:
Print the name of the zone the interface is bound to or no zone.
--info-zone=<zone> (which shows far more information than the manual indicates):
Print information about the zone zone. The output format is:
zone
interfaces: interface1 ..
sources: source1 ..
services: service1 ..
ports: port1 ..
protocols: protocol1 ..
forward-ports: forward-port1 ..
source-ports: source-port1 ..
icmp-blocks: icmp-type1 ..
rich rules: rich-rule1 ..
Two more notes before the examples:
- My first hunch was to use
--list-all-zones, but that shows details of all un-used zones as well.
- I am not fully sure about the
--list-interfaces to list *all* interfaces. I might replace this later with ls /sys/class/net (see [WayBack] linux – List only the device names of all available network interfaces – Super User).
Other useful commands
Besides lising zones and interfaces, you might be interested in services and ports:
# firewall-cmd --list-services
dhcpv6-client ssh
# firewall-cmd --list-ports
List used zones
The first only shows the zone names
# firewall-cmd --list-interfaces | xargs -I {} sh -c 'firewall-cmd --get-zone-of-interface={}'
public
The second both zones and interfaces:
# firewall-cmd --get-active-zones
public
interfaces: ens192
When there are no bound interfaces
OpenSuSE by default does not bind interfaces to zones; it means any interface uses the default zone. That means the --list-interfaces commands in this blog post fail.
You can check this behaviour by running this command:
# ls /sys/class/net | xargs -I {} sh -c 'echo -n "interface {} has zone " ; firewall-cmd --get-zone-of-interface={} | xargs -I [] sh -c "echo [] ; firewall-cmd --info-zone=[]"'
interface eth0 has zone no zone
interface lo has zone no zone
interface wlan0 has zone no zone
Alternatives:
- Finding the default zone
# firewall-cmd --get-default-zone
public
- Details of the default zone
# firewall-cmd --info-zone=$(firewall-cmd --get-default-zone)
public
target: default
icmp-block-inversion: no
interfaces:
sources:
services: dhcpv6-client ssh
ports:
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
You can see that here the public zone is marked default which means it binds to any interface that is not bound to a specific zone.
List used zone details
# firewall-cmd --list-interfaces | xargs -I {} sh -c 'firewall-cmd --get-zone-of-interface={} | xargs -I [] sh -c "firewall-cmd --info-zone=[]"'
public (active)
target: default
icmp-block-inversion: no
interfaces: ens192
sources:
services: dhcpv6-client ssh
ports:
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
List interfaces and their zones:
# firewall-cmd --list-interfaces | xargs -I {} sh -c 'echo -n "interface {} has zone " ; firewall-cmd --get-zone-of-interface={}'
interface ens192 has zone public
List interfaces and their zone details:
# firewall-cmd --list-interfaces | xargs -I {} sh -c 'echo -n "interface {} has zone " ; firewall-cmd --get-zone-of-interface={} | xargs -I [] sh -c "echo [] ; firewall-cmd --info-zone=[]"'
interface ens192 has zone public
public (active)
target: default
icmp-block-inversion: no
interfaces: ens192
sources:
services: dhcpv6-client ssh
ports:
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
Verifying if dns service is available, then allow it on public
Verify if a DNS is in the enabled services:
# firewall-cmd --list-services
dhcpv6-client ssh
Here no DNS service is enabled, so I need to figure out if any DNS service is available to be enabled.
This lists all the services that can be enabled in a zone:
# firewall-cmd --get-services
On my system, this returned the following list:
RH-Satellite-6 amanda-client amanda-k5-client amqp amqps apcupsd audit bacula bacula-client bb bgp bitcoin bitcoin-rpc bitcoin-testnet bitcoin-testnet-rpc bittorrent-lsd ceph ceph-mon cfengine cockpit condor-collector ctdb dhcp dhcpv6 dhcpv6-client distcc dns dns-over-tls docker-registry docker-swarm dropbox-lansync elasticsearch etcd-client etcd-server finger freeipa-4 freeipa-ldap freeipa-ldaps freeipa-replication freeipa-trust ftp ganglia-client ganglia-master git grafana gre http https imap imaps ipp ipp-client ipsec irc ircs iscsi-target isns jenkins kadmin kdeconnect kerberos kibana klogin kpasswd kprop kshell ldap ldaps libvirt libvirt-tls lightning-network llmnr managesieve matrix mdns memcache minidlna mongodb mosh mountd mqtt mqtt-tls ms-wbt mssql murmur mysql nfs nfs3 nmea-0183 nrpe ntp nut openvpn ovirt-imageio ovirt-storageconsole ovirt-vmconsole plex pmcd pmproxy pmwebapi pmwebapis pop3 pop3s postgresql privoxy prometheus proxy-dhcp ptp pulseaudio puppetmaster quassel radius rdp redis redis-sentinel rpc-bind rsh rsyncd rtsp salt-master samba samba-client samba-dc sane sip sips slp smtp smtp-submission smtps snmp snmptrap spideroak-lansync spotify-sync squid ssdp ssh steam-streaming svdrp svn syncthing syncthing-gui synergy syslog syslog-tls telnet tentacle tftp tftp-client tile38 tinc tor-socks transmission-client upnp-client vdsm vnc-server wbem-http wbem-https wsman wsmans xdmcp xmpp-bosh xmpp-client xmpp-local xmpp-server zabbix-agent zabbix-server
I was searching to see if dns was available, so I split the string with tr, then searced with grep:
# firewall-cmd --get-services | tr " " "\n" | grep dns
dns
dns-over-tls
mdns
To get details, use the firewall-cmd --info-service=servicename like this:
# firewall-cmd --get-services | tr " " "\n" | grep dns | xargs -I [] sh -c "firewall-cmd --info-service=[]"
dns
ports: 53/tcp 53/udp
protocols:
source-ports:
modules:
destination:
includes:
dns-over-tls
ports: 853/tcp
protocols:
source-ports:
modules:
destination:
includes:
mdns
ports: 5353/udp
protocols:
source-ports:
modules:
destination: ipv4:224.0.0.251 ipv6:ff02::fb
includes:
So for named (bind), I need the dns service to be enabled:
# firewall-cmd --zone=public --add-service=dns --permanent
success
Now a –list-services will not show dns as we changed the --permanent configuration, not the current configuration:
# firewall-cmd --list-services
dhcpv6-client ssh
So you need to --reload the --permanent settings:
# firewall-cmd --list-services --permanent
dhcpv6-client dns ssh
# firewall-cmd --reload
success
# firewall-cmd --list-services
dhcpv6-client dns ssh
–jeroen
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