'\" t .\" Title: firewalld.direct .\" Author: Thomas Woerner .\" Generator: DocBook XSL Stylesheets vsnapshot .\" Date: .\" Manual: firewalld.direct .\" Source: firewalld 2.0.0 .\" Language: English .\" .TH "FIREWALLD\&.DIRECT" "5" "" "firewalld 2.0.0" "firewalld.direct" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" firewalld.direct \- firewalld direct configuration file .SH "SYNOPSIS" .PP .nf \fI/etc/firewalld/direct\&.xml\fR .fi .sp .SH "DEPRECATED" .PP The direct interface has been deprecated\&. It will be removed in a future release\&. It is superseded by policies, see \fBfirewalld.policies\fR(5)\&. .SH "DESCRIPTION" .PP Direct configuration gives a more direct access to the firewall\&. It requires user to know basic ip(6)tables/ebtables concepts, i\&.e\&. \fItable\fR (filter/mangle/nat/\&.\&.\&.), \fIchain\fR (INPUT/OUTPUT/FORWARD/\&.\&.\&.), \fIcommands\fR (\-A/\-D/\-I/\&.\&.\&.), \fIparameters\fR (\-p/\-s/\-d/\-j/\&.\&.\&.) and \fItargets\fR (ACCEPT/DROP/REJECT/\&.\&.\&.)\&. Direct configuration should be used only as a last resort when it\*(Aqs not possible to use \fBfirewalld.zone\fR(5)\&. See also \fIDirect Options\fR in \fBfirewall-cmd\fR(1)\&. .PP A firewalld direct configuration file contains information about permanent direct chains, rules and passthrough \&.\&.\&. .PP This is the structure of a direct configuration file: .sp .if n \{\ .RS 4 .\} .nf [ ] [ args ] [ args ] .fi .if n \{\ .RE .\} .sp .SS "direct" .PP The mandatory direct start and end tag defines the direct\&. This tag can only be used once in a direct configuration file\&. There are no attributes for direct\&. .SS "chain" .PP Is an optional empty\-element tag and can be used several times\&. It can be used to define names for additional chains\&. A chain entry has exactly three attributes: .PP ipv="\fIipv4\fR|\fIipv6\fR|\fIeb\fR" .RS 4 The IP family where the chain will be created\&. This can be either \fIipv4\fR, \fIipv6\fR or \fIeb\fR\&. .RE .PP table="\fItable\fR" .RS 4 The table name where the chain will be created\&. This can be one of the tables that can be used for iptables, ip6tables or ebtables\&. For the possible values, see TABLES section in the iptables, ip6tables or ebtables man pages\&. .RE .PP chain="\fIchain\fR" .RS 4 The name of the chain, that will be created\&. Please make sure that there is no other chain with this name already\&. .RE .PP Please remember to add a rule or passthrough rule with an \fB\-\-jump\fR or \fB\-\-goto\fR option to connect the chain to another one\&. .SS "rule" .PP Is an optional element tag and can be used several times\&. It can be used to add rules to a built\-in or added chain\&. A rule entry has exactly four attributes: .PP ipv="\fIipv4\fR|\fIipv6\fR|\fIeb\fR" .RS 4 The IP family where the rule will be added\&. This can be either \fIipv4\fR, \fIipv6\fR or \fIeb\fR\&. .RE .PP table="\fItable\fR" .RS 4 The table name where the rule will be added\&. This can be one of the tables that can be used for iptables, ip6tables or ebtables\&. For the possible values, see TABLES section in the iptables, ip6tables or ebtables man pages\&. .RE .PP chain="\fIchain\fR" .RS 4 The name of the chain where the rule will be added\&. This can be either a built\-in chain or a chain that has been created with the chain tag\&. If the chain name is a built\-in chain, then the rule will be added to \fIchain\fR_direct, else the supplied chain name is used\&. \fIchain\fR_direct is created internally for all built\-in chains to make sure that the added rules do not conflict with the rules created by firewalld\&. .RE .PP priority="\fIpriority\fR" .RS 4 The priority is used to order rules\&. Priority 0 means add rule on top of the chain, with a higher priority the rule will be added further down\&. Rules with the same priority are on the same level and the order of these rules is not fixed and may change\&. If you want to make sure that a rule will be added after another one, use a low priority for the first and a higher for the following\&. .RE .PP The \fIargs\fR can be any arguments of iptables or ip6tables, that do not conflict with the table or chain attributes\&. .SS "passthrough" .PP Is an optional element tag and can be used several times\&. It can be used to add rules to a built\-in or added chain\&. A rule entry has exactly one attribute: .PP ipv="\fIipv4\fR|\fIipv6\fR|\fIeb\fR" .RS 4 The IP family where the passthrough rule will be added\&. This can be either \fIipv4\fR, \fIipv6\fR or \fIeb\fR\&. .RE .PP The \fIargs\fR can be any arguments of iptables or ip6tables\&. .PP The passthrough rule will be added to the chain directly\&. There is no mechanism like for the direct \fBrule\fR above\&. The user of the passthrough rule has to make sure that there will be no conflict with the rules created by firewalld\&. .SH "CAVEATS" .PP Depending on the value of \fIFirewallBackend\fR (see \fBfirewalld.conf\fR(5)) direct rules behave differently in some scenarios\&. .SS "Packet accept/drop precedence" .PP Due to implementation details of netfilter inside the kernel, if \fIFirewallBackend=nftables\fR is used direct rules that \fIACCEPT\fR packets don\*(Aqt actually cause the packets to be immediately accepted by the system\&. Those packets are still be subject to firewalld\*(Aqs nftables ruleset\&. This basically means there are two independent firewalls and packets must be accepted by both (iptables and nftables)\&. As an aside, this scenario also occurs inside of nftables (again due to netfilter) if there are multiple chains attached to the same hook \- it\*(Aqs not as simple as iptables vs nftables\&. .PP There are a handful of options to workaround the \fIACCEPT\fR issue: .sp .RS 4 .ie n \{\ \h'-04' 1.\h'+01'\c .\} .el \{\ .sp -1 .IP " 1." 4.2 .\} Rich Rules .sp If a rich rule can be used, then they should always be preferred over direct rules\&. Rich Rules will be converted to the enabled \fIFirewallBackend\fR\&. See \fBfirewalld.richlanguage\fR(5)\&. .RE .sp .RS 4 .ie n \{\ \h'-04' 2.\h'+01'\c .\} .el \{\ .sp -1 .IP " 2." 4.2 .\} Blanket Accept .sp Users can add an explicit accept to the nftables ruleset\&. This can be done by adding the interface or source to the \fItrusted\fR zone\&. .sp This strategy is often employed by things that perform their own filtering such as: libvirt, podman, docker\&. .sp \fBWarning\fR: This means firewalld will do no filtering on these packets\&. It must all be done via direct rules or out\-of\-band iptables rules\&. .RE .sp .RS 4 .ie n \{\ \h'-04' 3.\h'+01'\c .\} .el \{\ .sp -1 .IP " 3." 4.2 .\} Selective Accept .sp Alternatively, enable only the relevant service, port, address, or otherwise in the appropriate zone\&. .RE .sp .RS 4 .ie n \{\ \h'-04' 4.\h'+01'\c .\} .el \{\ .sp -1 .IP " 4." 4.2 .\} Revert to the iptables backend .sp A last resort is to revert to the iptables backend by setting \fIFirewallBackend=iptables\fR\&. Users should be aware that firewalld development focuses on the nftables backend\&. .RE .PP For direct rules that \fIDROP\fR packets the packets are immediately dropped regardless of the value of \fIFirewallBackend\fR\&. As such, there is no special consideration needed\&. .PP Firewalld guarantees the above ACCEPT/DROP behavior by registering nftables hooks with a lower precedence than iptables hooks\&. .SS "Direct interface precedence" .PP With \fIFirewallBackend=iptables\fR firewalld\*(Aqs top\-level internal rules apply before direct rules are executed\&. This includes rules to accept existing connections\&. In the past this has surprised users\&. As an example, if a user adds a direct rule to drop traffic on destination port 22 existing SSH sessions would continue to function, but new connections would be denied\&. .PP With \fIFirewallBackend=nftables\fR direct rules were deliberately given a higher precedence than all other firewalld rules\&. This includes rules to accept existing connections\&. .SH "EXAMPLE" .PP Denylisting of the networks 192\&.168\&.1\&.0/24 and 192\&.168\&.5\&.0/24 with logging and dropping early in the raw table: .sp .if n \{\ .RS 4 .\} .nf \-s 192\&.168\&.1\&.0/24 \-j denylist \-s 192\&.168\&.5\&.0/24 \-j denylist \-m limit \-\-limit 1/min \-j LOG \-\-log\-prefix "denylisted: " \-j DROP .fi .if n \{\ .RE .\} .sp .SH "SEE ALSO" \fBfirewall-applet\fR(1), \fBfirewalld\fR(1), \fBfirewall-cmd\fR(1), \fBfirewall-config\fR(1), \fBfirewalld.conf\fR(5), \fBfirewalld.direct\fR(5), \fBfirewalld.dbus\fR(5), \fBfirewalld.icmptype\fR(5), \fBfirewalld.lockdown-whitelist\fR(5), \fBfirewall-offline-cmd\fR(1), \fBfirewalld.richlanguage\fR(5), \fBfirewalld.service\fR(5), \fBfirewalld.zone\fR(5), \fBfirewalld.zones\fR(5), \fBfirewalld.policy\fR(5), \fBfirewalld.policies\fR(5), \fBfirewalld.ipset\fR(5), \fBfirewalld.helper\fR(5) .SH "NOTES" .PP firewalld home page: .RS 4 \m[blue]\fB\%http://firewalld.org\fR\m[] .RE .PP More documentation with examples: .RS 4 \m[blue]\fB\%http://fedoraproject.org/wiki/FirewallD\fR\m[] .RE .SH "AUTHORS" .PP \fBThomas Woerner\fR <\&twoerner@redhat\&.com\&> .RS 4 Developer .RE .PP \fBJiri Popelka\fR <\&jpopelka@redhat\&.com\&> .RS 4 Developer .RE .PP \fBEric Garver\fR <\&eric@garver\&.life\&> .RS 4 Developer .RE