Provided by: shorewall_5.2.8-5_all 
NAME
shorewall.conf - Shorewall global configuration file
SYNOPSIS
/etc/shorewall/shorewall.conf
/etc/shorewall6/shorewall6.conf
DESCRIPTION
The IPv4 and IPv6 environments each have their own configuration. The IPv4 configuration resides in
/etc/shorewall/ while the IPv6 configuration resides in /etc/shorewall6/.
The .conf files set options that apply to Shorewall and Shorewall6 as a whole.
The .conf files consist of Shell comments (lines beginning with '#'), blank lines and assignment
statements (variable=value). If the value contains shell meta characters or white-space, then it must be
enclosed in quotes. Example: MACLIST_LOG_LEVEL="NFLOG(1,0,1)".
OPTIONS
Many options have as their value a log-level. Log levels are a method of describing to syslog (8) the
importance of a message and a number of parameters in this file have log levels as their value.
These levels are defined by syslog and are used to determine the destination of the messages through
entries in /etc/syslog.conf (5). The syslog documentation refers to these as "priorities"; Netfilter
calls them "levels" and Shorewall also uses that term.
Valid levels are:
7 debug
6 info
5 notice
4 warning
3 err
2 crit
1 alert
0 emerg
For most Shorewall logging, a level of 6 (info) is appropriate. Shorewall log messages are generated by
NetFilter and are logged using facility 'kern' and the level that you specify. If you are unsure of the
level to choose, 6 (info) is a safe bet. You may specify levels by name or by number.
If you have built your kernel with ULOG (IPv4 only) and/or NFLOG target support, you may also specify a
log level of ULOG and/or NFLOG (must be all caps). Rather than log its messages to syslogd, Shorewall
will direct netfilter to log the messages via the ULOG or NFLOG target which will send them to a process
called 'ulogd'. ulogd is available with most Linux distributions (although it probably isn't installed by
default).
Note
If you want to specify parameters to ULOG or NFLOG (e.g., NFLOG(1,0,1)), then you must quote the
setting.
Example:
LOG_LEVEL="NFLOG(1,0,1)"
Beginning with Shorewall 5.0.0, the log level may be followed by a colon (":") and a log tag. The log tag
normally follows the packet disposition in Shorewall-generated Netfilter log messages, separated from the
disposition by a colon (e.g, "DROP:mytag"). See LOGTAGONLY below for additional information.
Beginning with Shorewall 4.4.22, LOGMARK is also a valid level which logs the packet's mark value along
with the other usual information. The syntax is:
LOGMARK[(priority)]
where priority is one of the levels listed in the list above. If omitted, the default is info (6).
The following options may be set in shorewall.conf.
ACCEPT_DEFAULT={action[(parameters)][:level][,...]|none}
BLACKLIST_DEFAULT={action[(parameters)][:level][,...]|none}
DROP_DEFAULT={action[(parameters)][:level][,...]|none}
NFQUEUE_DEFAULT={action[(parameters)][:level][,...]|none}
QUEUE_DEFAULT={action[(parameters)][:level][,...]|none}
REJECT_DEFAULT={action[(parameters)][:level][,...]|none}
In earlier Shorewall versions, a "default action" for DROP and REJECT policies was specified in the
file /usr/share/shorewall/actions.std.
In Shorewall 4.4.0, the DROP_DEFAULT, REJECT_DEFAULT, ACCEPT_DEFAULT, QUEUE_DEFAULT and
NFQUEUE_DEFAULT options were added.
DROP_DEFAULT describes the rules to be applied before a connection request is dropped by a DROP
policy; REJECT_DEFAULT describes the rules to be applied if a connection request is rejected by a
REJECT policy. The other three are similar for ACCEPT, QUEUE and NFQUEUE policies.
The value applied to these may be:
a) The name of an action. The
name may optionally be followed by a comma-separated list of
parameters enclosed in parentheses if the specified action accepts
parameters (e.g., 'Drop(audit)').
c) None or none
Prior to Shorewall 5.1.2, the default values are:
DROP_DEFAULT="Drop"
REJECT_DEFAULT="Reject"
BLACKLIST_DEFAULT="Drop" (added in Shorewall
5.1.1)
ACCEPT_DEFAULT="none"
QUEUE_DEFAULT="none"
NFQUEUE_DEFAULT="none"
Beginning with Shorewall 5.1.2, the default value is 'none' for all of these. Note that the sample
configuration files do, however, provide settings for DROP_DEFAULT, BLACKLIST_DEFAULT and
REJECT_DEFAULT.
If you set the value of either option to "None" then no default action will be used and the default
action or macro must be specified in shorewall-policy[1](5).
You can pass parameters to the specified action (e.g., myaction(audit,DROP)).
Beginning with Shorewall 4.5.10, the action name can be followed optionally by a colon and a log
level. The level will be applied to each rule in the action or body that does not already have a log
level.
Beginning with Shorewall 5.1.2, multiple action[(parameters)][:level] specifications may be listed,
separated by commas.
ACCOUNTING=[Yes|No]
Added in Shorewall 4.4.7. If set to Yes, Shorewall accounting is enabled (see
shorewall-accounting[2](5)). If not specified or set to the empty value, ACCOUNTING=Yes is assumed.
ACCOUNTING_TABLE=[filter|mangle]
Added in Shorewall 4.4.20. This setting determines which Netfilter table the accounting rules are
added in. By default, ACCOUNTING_TABLE=filter is assumed. See also shorewall-accounting[2](5).
ADD_IP_ALIASES=[Yes|No]
This parameter determines whether Shorewall automatically adds the external address(es) in
shorewall-nat[3](5), and is only available in IPv4 configurations. If the variable is set to Yes or
yes then Shorewall automatically adds these aliases. If it is set to No or no, you must add these
aliases yourself using your distribution's network configuration tools.
If this variable is not set or is given an empty value (ADD_IP_ALIASES="") then ADD_IP_ALIASES=Yes is
assumed.
Warning
Addresses added by ADD_IP_ALIASES=Yes are deleted and re-added during shorewall reload and
shorewall restart. As a consequence, connections using those addresses may be severed.
ADD_SNAT_ALIASES=[Yes|No]
This parameter determines whether Shorewall automatically adds the SNAT ADDRESS in
shorewall-masq[4](5), and is only available in IPv4 configurations. If the variable is set to Yes or
yes then Shorewall automatically adds these addresses. If it is set to No or no, you must add these
addresses yourself using your distribution's network configuration tools.
If this variable is not set or is given an empty value (ADD_SNAT_ALIASES="") then ADD_SNAT_ALIASES=No
is assumed.
Warning
Addresses added by ADD_SNAT_ALIASES=Yes are deleted and re-added during shorewall reload and
shorewall restart. As a consequence, connections using those addresses may be severed.
ADMINISABSENTMINDED=[Yes|No]
The value of this variable affects Shorewall's stopped state. The behavior differs depending on
whether shorewall-routestopped[5](5) or shorewall-stoppedrules[6](5) is used:
routestopped
When ADMINISABSENTMINDED=No, only traffic to/from those addresses listed in routestopped is
accepted when Shorewall is stopped. When ADMINISABSENTMINDED=Yes, in addition to traffic to/from
addresses in routestopped, connections that were active when Shorewall stopped continue to work
and all new connections from the firewall system itself are allowed.
Note that the routestopped file is not supported in Shorewall 5.0 and later versions.
stoppedrules
All existing connections continue to work. To sever all existing connections when the firewall is
stopped, install the conntrack utility and place the command conntrack -F in the stopped user
exit (/etc/shorewall/stopped).
If ADMINISABSENTMINDED=No, only new connections matching entries in stoppedrules are accepted
when Shorewall is stopped. Response packets and related connections are automatically accepted.
If ADMINISABSENTMINDED=Yes, in addition to connections matching entries in stoppedrules, all new
connections from the firewall system itself are allowed when the firewall is stopped. Response
packets and related connections are automatically accepted.
If this variable is not set or is given the empty value then ADMINISABSENTMINDED=No is assumed.
ARPTABLES=[pathname]
Added in Shorewall 4.5.12 and available in IPv4 only. This parameter names the arptables executable
to be used by Shorewall. If not specified or if specified as a null value, then the arptables
executable located using the PATH option is used.
Regardless of how the arptables utility is located (specified via arptables= or located via PATH),
Shorewall uses the arptables-restore and arptables-save utilities from that same directory.
AUTOCOMMENT=[Yes|No]
Formerly named AUTO_COMMENT. If set, if there is not a current comment when a macro is invoked, the
behavior is as if the first line of the macro file was "COMMENT <macro name>". If not specified, the
AUTO_COMMENT option has a default value of 'Yes'.
AUTOHELPERS=[Yes|No]
Added in Shorewall 4.5.7. When set to Yes (the default), the generated ruleset will automatically
associate helpers with applications that require them (FTP, IRC, etc.). When configuring your
firewall on systems running kernel 3.5 or later, it is recommended that you:
1. Set AUTOHELPERS=No.
2. Modify the HELPERS setting (see below) to list the helpers that you need.
3. Either:
1. Modify shorewall-conntrack[7] (5) to only apply helpers where they are required; or
2. Specify the appropriate helper in the HELPER column in shorewall-rules[8] (5).
Note
The macros for those applications requiring a helper automatically specify the
appropriate HELPER where required.
AUTOMAKE=[Yes|No|recursive|depth]
If set, the behavior of the start, reload and restart commands are changed; if no files in
CONFIG_PATH (see below) have been changed since the last successful start, reload or restart command,
then the compilation step is skipped and the compiled script that executed the last start, reload or
restart command is used. If not specified, the default is AUTOMAKE=No.
The setting of the AUTOMAKE option is ignored if the start, reload or restart command includes a
directory name (e.g., shorewall restart /etc/shorewall.new).
When AUTOMAKE=Yes, each directory in the CONFIG_PATH was originally searched recursively for files
newer than the compiled script. That was changed in Shorewall 5.1.10.2 such that only the listed
directories themselves were searched. That broke some configurations that played tricks with embedded
SHELL such as "SHELL cat /etc/shorewall/rules.d/loc/*.rules". Prior to 5.1.10.2, a change to a file
in or adding a file to /etc/shorewall/rules.d/loc/ would trigger recompilation. Beginning with
5.1.10.2, such changes would not trigger recompilation. Beginning with Shorewall 5.2.0, the
pre-5.1.10.2 behavior can be obtained by setting AUTOMAKE=recursive.
Also beginning with Shorewall 5.2.0, AUTOMAKE may be set to a numeric depth which specifies how
deeply each listed directory is to be searched. AUTOMAKE=1 only searches each directory itself and is
equivalent to AUTOMAKE=Yes. AUTOMAKE=2 will search each directory and its immediate sub-directories;
AUTOMAKE=3 will search each directory, each of its immediate sub-directories, and each of their
immediate sub-directories, etc.
BALANCE_PROVIDERS=[Yes|No]
Added in Shorewall 5.1.1. When USE_DEFAULT_RT=Yes, this option determines whether the balance
provider option (see shorewall-providers(5)[9]) is the default. When BALANCE_PROVIDERS=Yes, then the
balance option is assumed unless the fallback, loose, load or tproxy option is specified. If this
option is not set or is set to the empty value, then the default value is the value of
USE_DEFAULT_RT.
BASIC_FILTERS=[Yes|No]
Added in Shorewall-4.6.0. When set to Yes, causes entries in shorewall-tcfilters(5)[10] to generate a
basic filter rather than a u32 filter. This setting requires the Basic Ematch capability in your
kernel and iptables.
Note
One of the advantages of basic filters is that ipset matches are supported in newer iproute2 and
kernel versions. Because Shorewall cannot reliably detect this capability, use of basic filters
is controlled by this option.
The default value is No which causes u32 filters to be generated.
BLACKLIST=[{ALL|state[,...]}]
where state is one of NEW, ESTABLISHED, RELATED, INVALID,or UNTRACKED.
Added in Shorewall 4.5.13 to replace the BLACKLISTNEWONLY option. Specifies the connection tracking
states that are to be subject to blacklist screening. If BLACKLIST is not specified then the states
subject to blacklisting are NEW,ESTABLISHED,INVALID,UNTRACKED.
ALL sends all packets through the blacklist chains.
Note: The ESTABLISHED state may not be specified if FASTACCEPT=Yes is specified.
BLACKLIST_DISPOSITION=[DROP|A_DROP|REJECT|A_REJECT]
This parameter determines the disposition of packets from blacklisted hosts. It may have the value
DROP if the packets are to be dropped or REJECT if the packets are to be replied with an ICMP port
unreachable reply or a TCP RST (tcp only). If you do not assign a value or if you assign an empty
value then DROP is assumed.
A_DROP and A_REJECT are audited versions of DROP and REJECT respectively and were added in Shorewall
4.4.20. They require AUDIT_TARGET in the kernel and iptables.
The BLACKLIST_DISPOSITION setting determines the disposition of packets sent to the blacklog target
of shorewall-blrules[11](5), but otherwise does not affect entries in that file.
BLACKLIST_LOG_LEVEL=[log-level[:log-tag]]
Formerly named BLACKLIST_LOGLEVEL. This parameter determines if packets from blacklisted hosts are
logged and it determines the syslog level that they are to be logged at. Its value is a syslog level
(Example: BLACKLIST_LOG_LEVEL=debug). If you do not assign a value or if you assign an empty value
then packets from blacklisted hosts are not logged. The setting determines the log level of packets
sent to the blacklog target of shorewall-blrules[11](5).
CLAMPMSS=[Yes|No|value]
This parameter enables the TCP Clamp MSS to PMTU feature of Netfilter and is usually required when
your internet connection is through PPPoE or PPTP. If set to Yes or yes, the feature is enabled. If
left blank or set to No or no, the feature is not enabled.
Important: This option requires CONFIG_IP_NF_TARGET_TCPMSS in your kernel.
You may also set CLAMPMSS to a numeric value (e.g., CLAMPMSS=1400). This will set the MSS field in
TCP SYN packets going through the firewall to the value that you specify.
CLEAR_TC=[Yes|No]
If this option is set to No then Shorewall won't clear the current traffic control rules during
[re]start or reload. This setting is intended for use by people who prefer to configure traffic
shaping when the network interfaces come up rather than when the firewall is started. If that is what
you want to do, set TC_ENABLED=Yes and CLEAR_TC=No and do not supply an /etc/shorewall/tcstart file.
That way, your traffic shaping rules can still use the “fwmark” classifier based on packet marking
defined in shorewall-tcrules[12](5). If not specified, CLEAR_TC=Yes is assumed.
Warning
When you specify TC_ENABLED=shared (see below), then you should also specify CLEAR_TC=No.
COMPLETE=[Yes|No]
Added in Shorewall 4.4.12. When you set this option to Yes, you are asserting that the configuration
is complete so that your set of zones encompasses any hosts that can send or receive traffic
to/from/through the firewall. This causes Shorewall to omit the rules that catch packets in which the
source or destination IP address is outside of any of your zones. Default is No. It is recommended
that this option only be set to Yes if:
• You have defined an interface whose effective physical setting is '+'.
• That interface is assigned to a zone.
• You have no CONTINUE policies or rules.
CONFIG_PATH=[[:]directory[:directory]...]
Specifies where configuration files other than shorewall[6].conf may be found. CONFIG_PATH is
specifies as a list of directory names separated by colons (":"). When looking for a configuration
file:
• If the command is "try" or a "<configuration directory>" was specified in the command (e.g.,
shorewall [-6] check ./gateway) then the directory given in the command is searched first.
• Next, each directory in the CONFIG_PATH setting is searched in sequence.
If CONFIG_PATH is not given or if it is set to the empty value then the contents of
/usr/share/shorewall/configpath are used. As released from shorewall.net, that file sets the
CONFIG_PATH to /etc/shorewall:/usr/share/shorewall but your particular distribution may set it
differently. See the output of shorewall show config for the default on your system.
Beginning with Shorewall 5.1.10, the CONFIG_PATH setting may begin with a colon (":"), to signal that
the first directory listed will be skipped if the user performing a compilation is not root or if the
configuration is being compiled for export (-e option specified or if running one of the remote-*
commands) . This prevents the compiler from looking in /etc/shorewall[6]/ when compilation is being
done by a non-root user or if the generated script is to be sent to a remote firewall system.
DEFER_DNS_RESOLUTION=[Yes|No]
Added in Shorewall 4.5.12. When set to 'Yes' (the default), DNS names are validated in the compiler
and then passed on to the generated script where they are resolved by ip[6]tables-restore. This is an
advantage if you use AUTOMAKE=Yes and the IP address associated with the DNS name is subject to
change. When DEFER_DNS_RESOLUTION=No, DNS names are converted into IP addresses by the compiler. This
has the advantage that when AUTOMAKE=Yes, the start, reload and restart commands will succeed even if
no DNS server is reachable (assuming that the configuration hasn't changed since the compiled script
was last generated).
Important
When DEFER_DNS_RESOLUTION=No and AUTOMAKE=Yes and a DNS change makes it necessary to recompile an
existing firewall script, the -c option must be used with the reload or restart command to force
recompilation.
DELETE_THEN_ADD={Yes|No}
If set to Yes (the default value), entries in the /etc/shorewall[6]/rtrules files cause an 'ip rule
del' command to be generated in addition to an 'ip rule add' command. Setting this option to No,
causes the 'ip rule del' command to be omitted.
DETECT_DNAT_IPADDRS=[Yes|No]
IPv4 only.
If set to Yes or yes, Shorewall will detect the first IP address of the interface to the source zone
and will include this address in DNAT rules as the original destination IP address. If set to No or
no, Shorewall will not detect this address and any destination IP address will match the DNAT rule.
If not specified or empty, “DETECT_DNAT_IPADDRS=Yes” is assumed.
DISABLE_IPV6=[Yes|No]
IPv4 only.
If set to Yes or yes, IPv6 traffic to, from and through the firewall system is disabled. If set to No
or no, Shorewall will take no action with respect to allowing or disallowing IPv6 traffic. If not
specified or empty, “DISABLE_IPV6=No” is assumed.
It is important to note that changing DISABLE_IPV6=Yes to DISABLE_IPV6=No does not enable IPV6. The
recommended approach for enabling IPv6 on your system is:
• Install, configure and start Shorewall6[13].
• Change DISABLE_IPV6=Yes to DISABLE_IPV6=No in /etc/shorewall/shorewall.conf.
• Reload Shorewall
DOCKER=[Yes|No]
Added in Shorewall 5.0.6; IPv4 only. When set to Yes, the generated script will save Docker-generated
rules before and restore them after executing the start, stop, reload and restart commands. If set to
No (the default), the generated script will delete any Docker-generated rules when executing those
commands. Seehttps://shorewall.org/Docker.html[14] for additional information.
DOCKER_BRIDGE=[bridgename]
Added in Shorewall 5.2.4; IPv4 only. Specifies the name of the default Docker bridge. If not
specified, the value 'docker0' is assumed.
DONT_LOAD=[module[,module]...]
Causes Shorewall to not load the listed kernel modules.
DYNAMIC_BLACKLIST={Yes|No||ipset[-only][,option[,...]][:[setname][:log_level|:log_tag]]]}
Added in Shorewall 4.4.7. When set to No or no, chain-based dynamic blacklisting using shorewall [-6]
[-l] drop, shorewall [-6] [-l] reject, shorewall logdrop and shorewall [-6] [-l] logreject is
disabled. Default is Yes. Beginning with Shorewall 5.0.8, ipset-based dynamic blacklisting using the
shorewall blacklist command is also supported. The name of the set (setname) and the level
(log_level), if any, at which blacklisted traffic is to be logged may also be specified. The default
IPv4 set name is SW_DBL4 and the default IPv6 set name is SW_DBL6. The default log level is none (no
logging). If ipset-only is given, then chain-based dynamic blacklisting is disabled just as if
DYNAMIC_BLACKLISTING=No had been specified.
Possible options are:
src-dst
Normally, only packets whose source address matches an entry in the ipset are dropped. If src-dst
is included, then packets whose destination address matches an entry in the ipset are also
dropped.
disconnect
The disconnect option was added in Shorewall 5.0.13 and requires that the conntrack utility be
installed on the firewall system. When an address is blacklisted using the blacklist command, all
connections originating from that address are disconnected. if the src-dst option was also
specified, then all connections to that address are also disconnected.
timeout=seconds
Added in Shorewall 5.0.13. Normally, Shorewall creates the dynamic blacklisting ipset with
timeout 0 which means that entries are permanent. If you want entries in the set that are not
accessed for a period of time to be deleted from the set, you may specify that period using this
option. Note that the blacklist command can override the ipset's timeout setting.
Important
Once the dynamic blacklisting ipset has been created, changing this option setting requires a
complete restart of the firewall; shorewall [-6] restart if RESTART=restart, otherwise
shorewall [-6] [-l] stop && shorewall [-6] [-l] start
log
Added in Shorewall 5.2.5. When specified, successful 'blacklist' and 'allow' commands will log a
message to the system log.
noupdate
Added in Shorewall 5.2.5. Normally, once an address has been blacklisted, each time that a packet
is received from the packet, the ipset's entry for the address is updated to reset the timeout to
the value specifyed in the timeout option above. Setting the noupdate option, inhibits this
resetting of the entry's timeout. This option is ignored when the timeout option is not
specified.
When ipset-based dynamic blacklisting is enabled, the contents of the blacklist will be preserved
over stop/reboot/start sequences.
EXPAND_POLICIES={Yes|No}
Normally, when the SOURCE or DEST columns in shorewall-policy(5) contains 'all', a single policy
chain is created and thes policy is enforced in that chain. For example, if the policy entry is
#SOURCE DEST POLICY LOG
# LEVEL
net all DROP info
then the chain name is 'net-all' ('net2all if ZONE2ZONE=2) which is also the chain named in Shorewall
log messages generated as a result of the policy. If EXPAND_POLICIES=Yes, then Shorewall will create
a separate chain for each pair of zones covered by the policy. This makes the resulting log messages
easier to interpret since the chain in the messages will have a name of the form 'a2b' where 'a' is
the SOURCE zone and 'b' is the DEST zone.
EXPORTMODULES=[Yes|No]
Added in Shorewall 4.4.17. When set to Yes when compiling for use by Shorewall Lite (shorewall [-6]
remote-start, shorewall [-6] remote-reload, shorewall [-6] remote-restart or shorewall [-6] export
commands), the compiler will copy the modules or helpers file from the administrative system into the
script. When set to No or not specified, the compiler will not copy the modules or helpers file from
/usr/share/shorewall[6] but will copy those found in another location on the CONFIG_PATH.
When compiling for direct use by Shorewall, causes the contents of the local module or helpers file
to be copied into the compiled script. When set to No or not set, the compiled script reads the file
itself.
FASTACCEPT={Yes|No}
Normally, Shorewall defers accepting ESTABLISHED/RELATED packets until these packets reach the chain
in which the original connection was accepted. So for packets going from the 'loc' zone to the 'net'
zone, ESTABLISHED/RELATED packets are ACCEPTED in the 'loc-net' or 'loc2net' chain, depending on the
setting of ZONE2ZONE (see below).
If you set FASTACCEPT=Yes, then ESTABLISHED/RELATED packets are accepted early in the INPUT, FORWARD
and OUTPUT chains. If you set FASTACCEPT=Yes then you may not include rules in the ESTABLISHED or
RELATED sections of shorewall-rules[8](5).
FIREWALL=[dnsname-or-ip-address]
This option was added in Shorewall 5.0.13 and may be used on an administrative system in directories
containing the configurations of remote firewalls. The contents of the variable are the default value
for the system parameter to the remote-start, remote-reload and remote-restart commands.
FORWARD_CLEAR_MARK={Yes|No}
Added in Shorewall 4.4.11. Traditionally, Shorewall has cleared the packet mark in the first rule in
the mangle FORWARD chain. This behavior is maintained with the default setting of this option
(FORWARD_CLEAR_MARK=Yes). If FORWARD_CLEAR_MARK is set to 'No', packet marks set in the mangle
PREROUTING chain are retained in the FORWARD chains.
GEOIPDIR=[pathname]
Added in Shorewall 4.5.4. Specifies the pathname of the directory containing the GeoIP Match
database. See https://shorewall.org/ISO-3661.html[15]. If not specified, the default value is
/usr/share/xt_geoip/LE which is the default location of the little-endian database.
HELPERS=[helper[,helper...]]
Added in Shorewall 4.5.7. This option specifies a comma-separated list naming the Netfilter
application helpers that are to be enabled. If not specified, the default is to enable all helpers.
Possible values for helper are:
• amanda
• ftp
• h323
• irc
• netbios-ns
• none - This special value was added in Shorewall 4.5.16 and indicates that no helpers are to be
enabled. It also prevents the compiler for probing for helper support; such probing generates
messages on the system log of the form "xt_CT: No such helper XXX" where XXX is the helper name.
When used, none must be the only helper specified.
• pptp
• sane
• sip
• snmp
• tftp
When HELPERS is specified on a system running Kernel 3.5.0 or later, automatic association of helpers
to connections is disabled.
IGNOREUNKNOWNVARIABLES=[Yes|No]
Added in Shorewall 4.5.11. Normally, if an unknown shell variable is encountered in a configuration
file (except in ?IF and ?ELSIF directives), the compiler raises a fatal error. If
IGNOREUNKNOWNVARIABLES is set to Yes, then such variables simply expand to an empty string. Default
is No.
IMPLICIT_CONTINUE={Yes|No}
When this option is set to Yes, it causes subzones to be treated differently with respect to
policies.
Subzones are defined by following their name with ":" and a list of parent zones (in
shorewall-zones[16](5)). Normally, you want to have a set of special rules for the subzone and if a
connection doesn't match any of those subzone-specific rules then you want the parent zone rules and
policies to be applied; see shorewall-nesting[17](5). With IMPLICIT_CONTINUE=Yes, that happens
automatically.
If IMPLICIT_CONTINUE=No or if IMPLICIT_CONTINUE is not set, then subzones are not subject to this
special treatment. With IMPLICIT_CONTINUE=Yes, an implicit CONTINUE policy may be overridden by
including an explicit policy (one that does not specify "all" in either the SOURCE or the DEST
columns).
INVALID_DISPOSITION=[A_DROP|A_REJECT|DROP|REJECT|CONTINUE]
Added in Shorewall 4.5.13. Shorewall has traditionally passed INVALID packets through the NEW section
of shorewall-rules[8] (5). When a packet in INVALID state fails to match any rule in the INVALID
section, the packet is disposed of based on this setting. The default value is CONTINUE for
compatibility with earlier versions.
INVALID_LOG_LEVEL=log-level[:log-tag]
Added in Shorewall 4.5.13. Packets in the INVALID state that do not match any rule in the INVALID
section of shorewall-rules[8] (5) are logged at this level. The default value is empty which means no
logging is performed.
IP=[pathname]
If specified, gives the pathname of the 'ip' executable. If not specified, 'ip' is assumed and the
utility will be located using the current PATH setting.
IP_FORWARDING=[On|Off|Keep]
This IPv4 parameter determines whether Shorewall enables or disables IPv4 Packet Forwarding
(/proc/sys/net/ipv4/ip_forward). In an IPv6 configuration, this parameter determines the setting of
/proc/sys/net/ipv6/config/all/ip_forwarding.
Possible values are:
On or on
packet forwarding will be enabled.
Off or off
packet forwarding will be disabled.
Keep or keep
Shorewall will neither enable nor disable packet forwarding.
If this variable is not set or is given an empty value (IP_FORWARD="") then IP_FORWARD=On is assumed.
IPSET=[pathname]
If specified, gives the pathname of the 'ipset' executable. If not specified, 'ipset' is assumed and
the utility will be located using the current PATH setting.
IPSET_WARNINGS={Yes|No}
Added in Shorewall 4.5.2. Default is Yes. When set, causes the rules compiler to issue a warning
when:
• The compiler is being run by root and an ipset specified in the configuration does not exists.
Only one warning is issued for each missing ipset.
• When [src] is specified in a destination column and when [dst] is specified in a source column.
IPTABLES=[pathname]
IPv4 only.
This parameter names the iptables executable to be used by Shorewall. If not specified or if
specified as a null value, then the iptables executable located using the PATH option is used.
Regardless of how the iptables utility is located (specified via IPTABLES= or located via PATH),
Shorewall uses the iptables-restore and iptables-save utilities from that same directory.
IP6TABLES=[pathname]
IPv6 only.
This parameter names the ip6tables executable to be used by Shorewall6. If not specified or if
specified as a null value, then the ip6tables executable located using the PATH option is used.
Regardless of how the ip6tables utility is located (specified via IP6TABLES= or located via PATH),
Shorewall6 uses the ip6tables-restore and ip6tables-save utilities from that same directory.
KEEP_RT_TABLES={Yes|No}
IPv4: When set to Yes, this option prevents generated scripts from altering the
/etc/iproute2/rt_tables database when there are entries in /etc/shorewall/providers. If you set this
option to Yes while Shorewall (Shorewall-lite) is running, you should remove the file
/var/lib/shorewall/rt_tables (/var/lib/shorewall-lite/rt_tables) before your next stop, restore,
reload or restart command. IPv6: When set to Yes, this option prevents scripts generated by
Shorewall6 from altering the /etc/iproute2/rt_tables database when there are entries in
/etc/shorewall6/providers. If you set this option to Yes while Shorewall6 (Shorewall6-lite) is
running, you should remove the file /var/lib/shorewall6/rt_tables
(/var/lib/shorewall6-lite/rt_tables) before your next stop, restore, reload or restart command.
Important
When both IPv4 and IPv6 Shorewall configurations are present, KEEP_RT_TABLES=No should be
specified in only one of the two configurations unless the two provider configurations are
identical with respect to interface and provider names and numbers.
The default is KEEP_RT_TABLES=No.
LOAD_HELPERS_ONLY={Yes|No}
Added in Shorewall 4.4.7. When set to Yes, restricts the set of modules loaded by shorewall to those
listed in /var/lib/shorewall[6]/helpers and those that are actually used. When not set, or set to the
empty value, LOAD_HELPERS_ONLY=No is assumed in Shorewall versions 5.2.2 and earlier. Beginning with
Shorewall 5.2.3, the LOAD_HELPERS_ONLY option is removed, and the behavior is as if
LOAD_HELPERS_ONLY=Yes had been specified.
LOCKFILE=[pathname]
Specifies the name of the Shorewall[6] lock file, used to prevent simultaneous state-changing
commands. If not specified, ${VARDIR}/shorewall[6]/lock is assumed (${VARDIR} is normally /var/lib
but can be changed when Shorewall-core is installed -- see the output of shorewall show vardir).
LOG_BACKEND=[backend]
Added in Shorewall 4.6.4. LOG_BACKEND determines the logging backend to be used for the iptrace
command (see shorewall(8)[18]).
backend is one of:
LOG
Use standard kernel logging.
ULOG
IPv4 only.
Use ULOG logging to ulogd.
netlink
Use netlink logging to ulogd version 2 or later.
LOG_ZONE=[src|dst|both]
Added in Shorewall 5.2.0. When a log message is issued from a chain that relates to a pair of zones
(e.g, 'fw-net'), the chain name normally appears in the log message (unless LOGTAGONLY=Yes and a log
tag is specified). This can prevent OPTIMIZE category 8 from combining chains which are identical
except for the names of the zones involved. LOG_ZONE allows for only the source or destination zone
to appear in the messages by setting LOG_ZONE to src or dest respectively. If LOG_ZONE=both (the
default), then the full chain name is included in log messages.
LOG_LEVEL=log-level[:log-tag]
Added in Shorewall 5.1.2. Beginning with that release, the sample configurations use this as the
default log level and changing it will change all packet logging done by the configuration. In any
configuration file (except shorewall-params(5)[19]), $LOG_LEVEL will expand to this value.
LOG_MARTIANS=[Yes|No|Keep]
IPv4 only.
If set to Yes or yes, sets /proc/sys/net/ipv4/conf/*/log_martians to 1 with the exception of
/proc/sys/net/ipv4/conf/all/log_martians which is set to 0. The default value is Yes which sets both
of the above to one. If you do not enable martian logging for all interfaces, you may still enable it
for individual interfaces using the logmartians interface option in shorewall-interfaces[20](5).
The value Keep causes Shorewall to ignore the option. If the option is set to Yes, then martians are
logged on all interfaces. If the option is set to No, then martian logging is disabled on all
interfaces except those specified in shorewall-interfaces[20](5).
LOG_VERBOSITY=[number]
This option controls the amount of information logged to the file specified in the STARTUP_LOG
option.
Values are:
-1 - Logging is disabled
0 - Silent. Only error messages are logged.
1 - Major progress messages logged.
2 - All progress messages logged
If not specified, then -1 is assumed.
LOGALLNEW=[log-level]
This option is intended for use as a debugging aid. When set to a log level, this option causes
Shorewall to generate a logging rule as the first rule in each builtin chain.
• The table name is used as the chain name in the log prefix.
• The chain name is used as the target in the log prefix.
For example, using the default LOGFORMAT, the log prefix for logging from the nat table's PREROUTING
chain is as follows in versions prior to 5.1.0:
Shorewall:nat:PREROUTING
In Shorewall 5.1.0 and later releases, the log prefix is:
nat:PREROUTING
Important
To help insure that all packets in the NEW state are logged, rate limiting (LOGLIMIT) should be
disabled when using LOGALLNEW. Use LOGALLNEW at your own risk; it may cause high CPU and disk
utilization and you may not be able to control your firewall after you enable this option.
Caution
Do not use this option if the resulting log messages will be sent to another system.
LOGFILE=[pathname|systemd]
This parameter tells the /sbin/shorewall program where to look for Shorewall messages when processing
the dump, logwatch, show log, and hits commands. If not assigned or if assigned an empty value,
/var/log/messages is assumed. For further information, see shorewall-logging(8)[21]. Beginning with
Shorewall 5.0.10.1, you may specify systemd to use journelctl -r to read the log.
LOGFORMAT=["formattemplate"]
The value of this variable generate the --log-prefix setting for Shorewall logging rules. It contains
a “printf” formatting template which accepts three arguments (the chain name, logging rule number
(optional) and the disposition). To use LOGFORMAT with fireparse, set it as:
LOGFORMAT="fp=%s:%d a=%s "
If the LOGFORMAT value contains the substring “%d” then the logging rule number is calculated and
formatted in that position; if that substring is not included then the rule number is not included.
If not supplied or supplied as empty (LOGFORMAT="") then “Shorewall:%s:%s:” is assumed.
Note
The setting of LOGFORMAT has an effect of the permitted length of zone names. See
shorewall-zones[16] (5).
Caution
Beginning with Shorewall 5.1.0, the default and sample shorewall[6].conf files set LOGFORMAT="%s
%s ".
Regardless of the LOGFORMAT setting, Shorewall IPv4 log messages that use this LOGFORMAT can be
uniquely identified using the following regular expression:
'IN=.* OUT=.* SRC=.*\..* DST='
and Shorewall IPv6 log messages can be uniquely identified using the following regular
expression:
'IN=.* OUT=.* SRC=.*:.* DST='
To match all Netfilter log messages (Both IPv4 and IPv6 and regardless of the LOGFORMAT setting),
use:
'IN=.* OUT=.* SRC=.* DST='
LOGLIMIT=[[{s|d}:]rate/{sec|second|min|minute|hour|day}[:burst]]
Added in Shorewall 4.4.12. Limits the logging rate, either overall, or by source or destination IP
address.
If the value starts with 's:' then logging is limited per source IP. If the value starts with 'd:',
then logging is limited per destination IP. Otherwise, the overall logging rate is limited.
If burst is not specified, then a value of 5 is assumed.
The keywords second and minute are accepted beginning with Shorewall 4.6.13.
LOGTAGONLY=[Yes|No]
Using LOGFORMAT=“Shorewall:%s:%s:”, chain names may not exceed 5 characters or truncation of the log
prefix may occur. Longer chain names may be used with log tags if you set LOGTAGONLY=Yes. With
LOGTAGONLY=Yes, if a log tag is specified then the tag is included in the log prefix in place of the
chain name.
Beginning with Shorewall 4.5.12, when LOGTAGONLY=Yes, you have more control over the generated log
prefix. Beginning with that release, the tag is interpreted as a chain name and a disposition
separated by a comma. So this rule:
#ACTION SOURCE DEST
LOG:info:foo,bar net fw
would generate the following log prefix when using LOGFORMAT=“Shorewall:%s:%s:”:
Shorewall:foo:bar:
Similarly,
#ACTION SOURCE DEST
LOG:info:,bar net fw
would generate
Shorewall:net2fw:bar:
MACLIST_DISPOSITION=[ACCEPT|DROP|REJECT|A_DROP|A_REJECT]
Determines the disposition of connections requests that fail MAC Verification and must have the value
ACCEPT (accept the connection request anyway), REJECT (reject the connection request) or DROP (ignore
the connection request). If not set or if set to the empty value (e.g., MACLIST_DISPOSITION="") then
MACLIST_DISPOSITION=REJECT is assumed.
A_DROP and A_REJECT are audited versions of DROP and REJECT respectively and were added in Shorewall
4.4.20. They require AUDIT_TARGET in the kernel and ip[6]tables.
MACLIST_LOG_LEVEL=[log-level[:log-tag]]
Determines the syslog level for logging connection requests that fail MAC Verification. The value
must be a valid syslogd log level. If you don't want to log these connection requests, set to the
empty value (e.g., MACLIST_LOG_LEVEL="").
MACLIST_TABLE=[filter|mangle]
Normally, MAC verification occurs in the filter table (INPUT and FORWARD) chains. When forwarding a
packet from an interface with MAC verification to a bridge interface, that doesn't work.
This problem can be worked around by setting MACLIST_TABLE=mangle which will cause Mac verification
to occur out of the PREROUTING chain. Because REJECT isn't available in that environment, you may not
specify MACLIST_DISPOSITION=REJECT or MACLIST_DISPOSITION=A_REJECT with MACLIST_TABLE=mangle.
MACLIST_TTL=[number]
The performance of configurations with a large numbers of entries in shorewall-maclist[22](5) can be
improved by setting the MACLIST_TTL variable in shorewall[6].conf[23](5).
If your iptables and kernel support the "Recent Match" (see the output of "shorewall check" near the
top), you can cache the results of a 'maclist' file lookup and thus reduce the overhead associated
with MAC Verification.
When a new connection arrives from a 'maclist' interface, the packet passes through then list of
entries for that interface in shorewall-maclist[22](5). If there is a match then the source IP
address is added to the 'Recent' set for that interface. Subsequent connection attempts from that IP
address occurring within $MACLIST_TTL seconds will be accepted without having to scan all of the
entries. After $MACLIST_TTL from the first accepted connection request from an IP address, the next
connection request from that IP address will be checked against the entire list.
If MACLIST_TTL is not specified or is specified as empty (e.g, MACLIST_TTL="" or is specified as zero
then 'maclist' lookups will not be cached).
MANGLE_ENABLED=[Yes|No]
Determines whether Shorewall will generate rules in the Netfilter mangle table. Setting
MANGLE_ENABLED=No disables all Shorewall features that require the mangle table. The default is
MANGLE_ENABLED=Yes.
MINIUPNPD=[Yes|No]
Added in Shorewall 5.0.8. If set to Yes, Shorewall will create a chain in the nat table named
MINIUPNPD-POSTROUTING and will add jumps from POSTROUTING to that chain for each interface with the
upnpd option specified. Default is No.
MARK_IN_FORWARD_CHAIN=[Yes|No]
If your kernel has a FORWARD chain in the mangle table, you may set MARK_IN_FORWARD_CHAIN=Yes to
cause the marking specified in the tcrules file to occur in that chain rather than in the PREROUTING
chain. This permits you to mark inbound traffic based on its destination address when DNAT is in use.
To determine if your kernel has a FORWARD chain in the mangle table, use the shorewall [-6] show
mangle command; if a FORWARD chain is displayed then your kernel will support this option. If this
option is not specified or if it is given the empty value (e.g., MARK_IN_FORWARD_CHAIN="") then
MARK_IN_FORWARD_CHAIN=No is assumed.
MASK_BITS=[number]
Added in Shorewall 4.4.26. Number of bits on the right of the 32-bit packet mark to be masked when
clearing the traffic shaping mark. Must be >= TC_BITS and <= PROVIDER_OFFSET (if PROVIDER_OFFSET >
0). Prior to Shorewall 5.0.0, default value and the default values of the other mark layout options
is determined as follows:
Table 1. Default Packet Mark Layout
WIDE_TC_MARKS=No, HIGH_ROUTE_MARKS=No TC_BITS=8, PROVIDER_BITS=8,
PROVIDER_OFFSET=0,
MASK_BITS=8
WIDE_TC_MARKS=No, TC_BITS=8, PROVIDER_BITS=8,
HIGH_ROUTE_MARKS=Yes PROVIDER_OFFSET=8,
MASK_BITS=8
WIDE_TC_MARKS=Yes, TC_BITS=14, PROVIDER_BITS=8,
HIGH_ROUTE_MARKS=No PROVIDER_OFFSET=0,
MASK_BITS=16
WIDE_TC_MARKS=Yes, TC_BITS=14, PROVIDER_BITS=8,
HIGH_ROUTE_MARKS=Yes PROVIDER_OFFSET=16,
MASK_BITS=16
From 5.0.0 onward, the default value of MASK_BITS is 8, the default value of PROVIDER_BITS, TC_BITS,
MASK_BITS and PROVIDER_OFFSET is 8.
MODULESDIR=[[+]pathname[:pathname]...]
This parameter specifies the directory/directories where your kernel netfilter modules may be found.
If you leave the variable empty, Shorewall will supply the value
"/lib/modules/$uname/kernel/net/ipv${g_family}/netfilter:/lib/modules/$uname/kernel/net/netfilter:/lib/modules/$uname/kernel/net/sched:/lib/modules/$uname/extra:/lib/modules/$uname/extra/ipset"
where uname holds the output of 'uname -r' and g_family holds '4' in IPv4 configurations and '6' in
IPv6 configurations.
The option plus sign ('+') was added in Shorewall 5.0.3 and causes the listed pathnames to be
appended to the default list above.
MULTICAST=[Yes|No]
IPv4 only.
This option will normally be set to 'No' (the default). It should be set to 'Yes' under the following
circumstances:
1. You have an interface that has parallel zones defined via /etc/shorewall/hosts.
2. You want to forward multicast packets to two or more of those parallel zones.
In such cases, you will configure a destonly network on each zone receiving multicasts.
MUTEX_TIMEOUT=[seconds]
The value of this variable determines the number of seconds that programs will wait for exclusive
access to the Shorewall[6] lock file. After the number of seconds corresponding to the value of this
variable, programs will assume that the last program to hold the lock died without releasing the
lock.
If not set or set to the empty value, a value of 60 (60 seconds) is assumed.
An appropriate value for this parameter would be twice the length of time that it takes your firewall
system to process a shorewall [-6] restart command.
NFACCT=[pathname]
Added in Shorewall 4.5.7. Specifies the pathname of the nfacct utility. If not specified, Shorewall
will use the PATH setting to find the program.
NULL_ROUTE_RFC1918=[Yes|No|blackhole|unreachable|prohibit]
IPv4 only.
When set to Yes, causes Shorewall to null-route the IPv4 address ranges reserved by RFC1918. The
default value is 'No'.
When combined with route filtering (ROUTE_FILTER=Yes or routefilter in shorewall-interfaces[20](5)),
this option ensures that packets with an RFC1918 source address are only accepted from interfaces
having known routes to networks using such addresses.
Beginning with Shorewall 4.5.15, you may specify blackhole, unreachable or prohibit to set the type
of route to be created. See https://shorewall.org/MultiISP.html#null_routing[24].
OPTIMIZE=[value]
The specified value enables certain optimizations. Each optimization category is associated with a
power of two. To enable multiple optimization categories, simply add their corresponding numbers
together.
Beginning with Shorewall 4.5.20, you may specify OPTIMIZE=All to enable all optimization categories,
and you may also specify OPTIMIZE=None to disable optimization.
• Optimization category 1 - Traditionally, Shorewall has created rules for the complete matrix of
host groups defined by the zones, interfaces and hosts files. Any traffic that didn't correspond
to an element of that matrix was rejected in one of the built-in chains. When the matrix is
sparse, this results in lots of largely useless rules.
These extra rules can be eliminated by setting the 1 bit in OPTIMIZE.
The 1 bit setting also controls the suppression of redundant wildcard rules (those specifying
"all" in the SOURCE or DEST column). A wildcard rule is considered to be redundant when it has
the same ACTION and Log Level as the applicable policy.
Note
Optimization level 1 is ignored when optimization level 4 is also selected, since level 4
performs similar optimizations in a more robust way.
• Optimization category 2 - Added in Shorewall 4.4.7. When set, suppresses superfluous ACCEPT rules
in a policy chain that implements an ACCEPT policy. Any ACCEPT rules that immediately precede the
final blanket ACCEPT rule in the chain are now omitted.
• Optimization category 4 - Added in Shorewall 4.4.7. When set, causes short chains (those with
less than 2 rules) to be optimized away. The following chains are excluded from optimization:
• accounting chains (unless OPTIMIZE_ACCOUNTING=Yes)
• action chains (user-defined)
• 'blacklst' chain
• dynamic
• forwardUPnP
• UPnP (nat table)
Additionally:
• If a built-in chain has a single rule that branches to a second chain, then the rules from
the second chain are moved to the built-in chain and the target chain is omitted.
• Chains with no references are deleted.
• Accounting chains are subject to optimization if the OPTIMIZE_ACCOUNTING option is set to
'Yes'.
• If a chain ends with an unconditional branch to a second chain (other than to 'reject'), then
the branch is deleted from the first chain and the rules from the second chain are appended
to it.
An additional optimization was added in Shorewall 4.5.4. If the last rule in a chain is an
unqualified jump to a simple target, then all immediately preceding rules with the same simple
target are omitted.
For example, consider this chain:
-A fw-net -p udp --dport 67:68 -j ACCEPT
-A fw-net -p udp --sport 1194 -j ACCEPT
-A fw-net -p 41 -j ACCEPT
-A fw-net -j ACCEPT
Since all of the rules are jumps to the simple target ACCEPT, this chain is totally optimized
away and jumps to the chain are replace with jumps to ACCEPT.
• Optimization category 8 - Added in Shorewall 4.4.9. When set, causes chains with identical rules
to be collapsed into a single chain.
Warning
While Optimization category 8 can significantly reduce the size of the generated iptables
ruleset, it can also take significant system resources during compilation. If you find that
compilation takes an unreasonably long time, try disabling this category by setting
OPTIMIZE=23.
• Optimization category 16 - Added in Shorewall 4.4.26. When set, causes sequences of compatible
rules to be combined into a single rule. Rules are considered compatible if they differ only in
their destination ports and comments.
A sequence of compatible rules is often generated when macros are invoked in sequence.
The ability to combine adjacent rules is limited by two factors:
• Destination port lists may only be combined up to a maximum of 15 ports, where a port-pair
counts as two ports.
• Rules may only be combined until the length of their concatenated comment reaches 255
characters.
When either of these limits would be exceeded, the current combined rule is emitted and the
compiler attempts to combine rules beginning with the one that would have exceeded the limit.
Adjacent combined comments are separated by ', '. Empty comments at the front of a group of
combined comments are replaced by 'Others and'. Empty comments at the end of a group of combined
comments are replaced by 'and others'.
Beginning in Shorewall 4.5.10, this option also suppresses duplicate adjacent rules and duplicate
non-adjacent rules that don't include mark, connmark, dscp, ecn, set, tos or u32 matches.
Example 1:
Rules with comments "FOO", <empty> and "BAR" would result in the combined comment "FOO and
others, BAR".
Example 2:
Rules with comments <empty>, "FOO" and "BAR" would result in the combined comment "Others and
FOO, BAR". Note: Optimize level 16 requires "Extended Multi-port Match" in your iptables and
kernel.
In versions prior to 5.1.0, the default value is zero which disables all optimizations. Beginning
with Shorewall 5.1.0, the default value is All which enables all optimizations.
OPTIMIZE_ACCOUNTING=[Yes|No]
Added in Shorewall 4.4.7. If set to Yes, Shorewall accounting changes are subject to optimization
(OPTIMIZE=4,5,6 or 7). If not specified or set to the empty value, OPTIMIZE_ACCOUNTING=No is assumed.
PAGER=pathname
Added in Shorewall 5.0.6. Specifies a path name of a pager program like less or more. When PAGER is
given, the output of verbose status commands and the dump command are piped through the named program
when the output file is a terminal.
Beginning with Shorewall 5.0.12, the default value of this option is the DEFAULT_PAGER setting in
shorewallrc.
PATH=pathname[:pathname]...
Determines the order in which Shorewall searches directories for executable files.
PERL=pathname
Added in Shorewall 4.4.11 RC1. Specifies the path name of the Perl executable. Default is
/usr/bin/perl. If the pathname specified by this option does not exist or the named file is not
executable, then Shorewall falls back to /usr/bin/perl
PERL_HASH_SEED=seed|random
Added in Shorewall 5.1.4. Sets the Perl hash seed (an integer in the range 0-99999) when running the
Shorewall rules compiler. If not specified, the value 0 is assumed. If random is specified, a random
seed will be chosed by Perl. See perlsec(1) for additional information.
PROVIDER_BITS=[number]
Added in Shorewall 4.4.26. The number of bits in the 32-bit packet mark to be used for provider
numbers. May be zero. See MASK_BITS above for default value.
PROVIDER_OFFSET=[number]If
Added in Shorewall 4.4.26. The offset from the right (low-order end) of the provider number field in
the 32-bit packet mark. If non-zero, must be >= TC_BITS (Shorewall automatically adjusts
PROVIDER_OFFSET's value). PROVIDER_OFFSET + PROVIDER_BITS + ZONE_BITS must be < 32. See MASK_BITS
above for default value.
RCP_COMMAND="command"
RSH_COMMAND="command"
Earlier generations of Shorewall Lite required that remote root login via ssh be enabled in order to
use the load and reload commands. Beginning with release 3.9.5, you may define an alternative means
for accessing the remote firewall system. In that release, two new options were added to
shorewall.conf:
RSH_COMMAND
RCP_COMMAND
The default values for these are as follows:
RSH_COMMAND: ssh ${root}@${system} ${command}
RCP_COMMAND: scp ${files} ${root}@${system}:${destination}
Shell variables that will be set when the commands are invoked are as follows:
root - root user. Normally root but may be overridden using the '-r' option.
system - The name/IP address of the remote firewall system.
command - For RSH_COMMAND, the command to be executed on the firewall system.
files - For RCP_COMMAND, a space-separated list of files to be copied to the remote firewall system.
destination - The directory on the remote system that the files are to be copied into.
RELATED_DISPOSITION=[ACCEPT|A_ACCEPT|A_DROP|A_REJECT|DROP|REJECT|CONTINUE]
Added in Shorewall 4.4.27. Shorewall has traditionally ACCEPTed RELATED packets that don't match any
rule in the RELATED section of shorewall-rules[8] (5). Concern about the safety of this practice
resulted in the addition of this option. When a packet in RELATED state fails to match any rule in
the RELATED section, the packet is disposed of based on this setting. The default value is ACCEPT for
compatibility with earlier versions.
RELATED_LOG_LEVEL=log-level[:log-tag]
Added in Shorewall 4.4.27. Packets in the related state that do not match any rule in the RELATED
section of shorewall-rules[8] (5) are logged at this level. The default value is empty which means no
logging is performed.
REJECT_ACTION=action
Added in Shorewall 4.5.21. When a REJECT target is specified, Shorewall normally handles the response
as follows:
• If the destination address of the packet is a broadcast or multicast address, the packet is
dropped.
• if the protocol is ICMP (2) then the packet is dropped.
• if the protocol is TCP (6) then the packet is rejected with an RST.
• if the protocol is UDP (17) then the packet is rejected with an 'port-unreachable' ICMP.
• if the protocol is ICMP (1) then the packet is rejected with a 'host-unreachable' ICMP.
• if the protocol is ICMP6 (1) then the packet is rejected with a 'icmp6-addr-unreachable' ICMP6.
• otherwise, the packet is rejected with a 'host-prohibited' ICMP.
You can modify this behavior by implementing your own action that handles REJECT and specifying it's
name in this option. The nolog and noinline options will automatically be assumed for the specified
action.
The following action implements the default reject action:
?format 2
#TARGET SOURCE DEST PROTO
Broadcast(DROP) - - -
DROP - - 2
INLINE - - 6 ;; -j REJECT --reject-with tcp-reset
?if __ENHANCED_REJECT
INLINE - - 17 ;; -j REJECT
?if __IPV4
INLINE - - 1 ;; -j REJECT --reject-with icmp-host-unreachable
INLINE - - - ;; -j REJECT --reject-with icmp-host-prohibited
?else
INLINE - - 58 ;; -j REJECT --reject-with icmp6-addr-unreachable
INLINE - - - ;; -j REJECT --reject-with icmp6-adm-prohibited
?endif
?else
INLINE - - - ;; -j REJECT
?endif
RENAME_COMBINED=[Yes|No]
Added in Shorewall 5.2.0. Traditionally, when OPTIMIZE category 8 is enabled, identical chains are
combined under a name beginning with '~comb' or '~blacklist'. This behavior is maintained under the
default setting RENAME_COMBINED=Yes. If RENAMED_COMBINED=No, the chains are combined under the
original name of one of the chains.
REQUIRE_INTERFACE=[Yes|No]
Added in Shorewall 4.4.10. The default is No. If set to Yes, at least one optional interface must be
up in order for the firewall to be in the started state. Intended to be used with the Shorewall Init
Package[25].
RESTART=[restart|reload]
Added in Shorewall 5.0.1 to replace LEGACY_RESTART which was added in Shorewall 5.0.0. In that
release, the reload command was redefined to do what restart had done in earlier releases and restart
became a true restart (equivalent to stop followed by start). When RESTART=reload, the restart
command performs the same operation as the reload command making it compatible with earlier releases.
If not specified, RESTART=reload is assumed.
RESTORE_DEFAULT_ROUTE=[Yes|No]
This option determines whether to restore the default route saved when here are 'balance' providers
defined but all of them are down.
The default is RESTORE_DEFAULT_ROUTE=Yes which preserves the pre-4.2.6 behavior.
RESTORE_DEFAULT_ROUTE=No is appropriate when you don't want a default route in the main table
(USE_DEFAULT_RT=No) or in the default table (USE_DEFAULT_RT=Yes) when there are no balance providers
available. In that case, RESTORE_DEFAULT_ROUTE=No will cause any default route in the relevant table
to be deleted.
RESTORE_ROUTEMARKS=[Yes|No]
Added in Shorewall 4.5.9. When set to Yes (the default), provider marks are restored unconditionally
at the top of the mangle OUTPUT and PREROUTING chains, even if the saved mark is zero. When this
option is set to No, the mark is restored only if it is non-zero. If you have problems with IPSEC ESP
packets not being routed correctly on output, try setting this option to No.
RESTOREFILE=filename
Specifies the simple name of a file in /var/lib/shorewall to be used as the default restore script in
the shorewall [-6] save, shorewall [-6] restore, shorewall [-6] forget and shorewall [6] -f start
commands.
RETAIN_ALIASES={Yes|No}
IPv4 only.
During shorewall start, IP addresses to be added as a consequence of ADD_IP_ALIASES=Yes and
ADD_SNAT_ALIASES=Yes are quietly deleted when shorewall-nat[3](5) and shorewall-masq[4](5) are
processed then are re-added later. This is done to help ensure that the addresses can be added with
the specified labels but can have the undesirable side effect of causing routes to be quietly
deleted. When RETAIN_ALIASES is set to Yes, existing addresses will not be deleted. Regardless of the
setting of RETAIN_ALIASES, addresses added during shorewall start are still deleted at a subsequent
shorewall [stop, shorewall reload or shorewall restart.
ROUTE_FILTER=[Yes|No|Keep]
If this parameter is given the value Yes or yes then route filtering (anti-spoofing) is enabled on
all network interfaces which are brought up while Shorewall is in the started state. The default
value is no.
The value Keep causes Shorewall to ignore the option. If the option is set to Yes, then route
filtering occurs on all interfaces. If the option is set to No, then route filtering is disabled on
all interfaces except those specified in shorewall-interfaces[20](5).
Important
If you need to disable route filtering on any interface, then you must set ROUTE_FILTER=No then
set routefilter=1 or routefilter=2 on those interfaces where you want route filtering. See
shorewall-interfaces[20](5) for additional details.
RPFILTER_DISPOSITION=[DROP|REJECT|A_DROP|A_REJECT]
Added in Shorewall 4.5.7. Determines the disposition of packets entering from interfaces the rpfilter
option (see shorewall-interfaces[20](5)). Packets disposed of by this option are those whose response
packets would not be sent through the same interface receiving the packet.
RPFILTER_LOG_LEVEL=log-level[:log-tag]
Added in shorewall 4.5.7. Determines the logging of packets disposed via the RPFILTER_DISPOSITION.
The default value is info.
SAVE_ARPTABLES={Yes|No}
Added in Shorewall 4.5.12. If SAVE_ARPTABLES=Yes, then the current arptables contents will be saved
by shorewall save command and restored by shorewall restore command. Default value is No.
SAVE_IPSETS={Yes|No|ipv4|setlist}
Re-enabled in Shorewall 4.4.6. If SAVE_IPSETS=Yes, then the current contents of your ipsets will be
saved by the shorewall stop and shorewall save commands and restored by the shorewall start and
shorewall restore commands.
Beginning with Shorewall 4.6.4, you can restrict the set of ipsets saved by specifying a setlist (a
comma-separated list of ipv4 ipset names). You may also restrict the saved sets to just the ipv4 ones
by specifying ipv4.
SFILTER_DISPOSITION=[DROP|REJECT|A_DROP|A_REJECT]
Added in Shorewall 4.4.20. Determines the disposition of packets matching the sfilter option (see
shorewall-interfaces[20](5)) and of hairpin packets on interfaces without the routeback option.[26]
SFILTER_LOG_LEVEL=log-level[:log-tag]
Added on Shorewall 4.4.20. Determines the logging of packets matching the sfilter option (see
shorewall-interfaces[20](5)) and of hairpin packets on interfaces without the routeback option.[27]
The default is info. If you don't wish for these packets to be logged, use SFILTER_LOG_LEVEL=none.
SHOREWALL_SHELL=[pathname]
This option is used to specify the shell program to be used to interpret the compiled script. If not
specified or specified as a null value, /bin/sh is assumed. Using a light-weight shell such as ash or
dash can significantly improve performance.
SMURF_DISPOSITION=[DROP|A_DROP]
Added in Shorewall 4.4.20. The default setting is DROP which causes smurf packets (see the nosmurfs
option in shorewall-interfaces[20](5)) to be dropped. A_DROP causes the packets to be audited prior
to being dropped and requires AUDIT_TARGET support in the kernel and iptables.
SMURF_LOG_LEVEL=[log-level[:log-tag]]
Specifies the logging level for smurf packets (see the nosmurfs option in
shorewall-interfaces[20](5)). If set to the empty value ( SMURF_LOG_LEVEL="" ) then smurfs are not
logged.
STARTUP_ENABLED={Yes|No}
Determines if Shorewall is allowed to start. As released from shorewall.net, this option is set to
No. When set to Yes or yes, Shorewall may be started. Used as a guard against Shorewall being
accidentally started before it has been configured.
STARTUP_LOG=[pathname]
If specified, determines where Shorewall will log the details of each start, reload, restart, try,
and safe-* command. Logging verbosity is determined by the setting of LOG_VERBOSITY above.
SUBSYSLOCK=[pathname]
This parameter should be set to the name of a file that the firewall should create if it starts
successfully and remove when it stops. Creating and removing this file allows Shorewall to work with
your distribution's initscripts. For OpenSuSE, this should be set to /var/lock/subsys/shorewall
(var/lock/subsys/shorewall-lite if building for export). For Gentoo, it should be set to
/run/lock/shorewall (/run/lock/shorewall-lite). For Redhat and derivatives as well as Debian and
derivatives, the pathname should be omitted.
Important
Beginning with Shorewall 5.1.0, this setting is ignored when SERVICEDIR is non-empty in
${SHAREDIR}/shorewall/shorewallrc (usually /usr/share/shorewall/shorewallrc).
TC=[pathname]
If specified, gives the pathname of the 'tc' executable. If not specified, 'tc' is assumed and the
utility will be located using the current PATH setting.
TC_BITS=[number]
The number of bits at the low end of the 32-bit packet mark to be used for traffic shaping marking.
May be zero. See MASK_BITS above for default value.
TC_ENABLED=[Yes|No|Internal|Simple|Shared]
If you say Yes or yes here, Shorewall will use a script that you supply to configure traffic shaping.
The script must be named 'tcstart' and must be placed in a directory on your CONFIG_PATH.
If you say No or no then traffic shaping is not enabled.
If you set TC_ENABLED=Simple (Shorewall 4.4.6 and later), simple traffic shaping using
shorewall-tcinterfaces[28](5) and shorewall-tcpri[29](5) is enabled.
If you set TC_ENABLED=Internal or internal or leave the option empty then Shorewall will use its
builtin traffic shaper (tc4shorewall written by Arne Bernin.
Beginning with Shorewall 4.4.15, you can set TC_ENABLED=Shared. This allows you to configure the
tcdevices and tcclasses in your Shorewall6 configuration yet make them available to the compiler when
compiling your Shorewall configuration. In addition to setting TC_ENABLED=Shared, you need to create
symbolic links from your Shorewall configuration directory (normally /etc/shorewall/) to the
tcdevices and tcclasses files in your Shorewall6 configuration directory (normally /etc/shorewall6/).
TC_EXPERT={Yes|No}
Normally, Shorewall tries to protect users from themselves by preventing PREROUTING and OUTPUT
tcrules from being applied to packets that have been marked by the 'track' option in
shorewall-providers[9](5).
If you know what you are doing, you can set TC_EXPERT=Yes and Shorewall will not include these
cautionary checks.
TC_PRIOMAP=map
Added in Shorewall 4.4.6. Determines the mapping of a packet's TOS field to priority bands. See
shorewall-tcpri[29](5). The map consists of 16 space-separated digits with values 1, 2 or 3. A value
of 1 corresponds to Linux priority 0, 2 to Linux priority 1, and 3 to Linux Priority 2. The first
entry gives the priority of TOS value 0, the second of TOS value 1, and so on. See tc-prio(8) for
additional information.
The default setting is TC_PRIOMAP="2 3 3 3 2 3 1 1 2 2 2 2 2 2 2 2".
TCP_FLAGS_DISPOSITION=[ACCEPT|DROP|REJECT|A_DROP|A_REJECT]
Determines the disposition of TCP packets that fail the checks enabled by the tcpflags interface
option (see shorewall-interfaces[20](5)) and must have a value of ACCEPT (accept the packet), REJECT
(send an RST response) or DROP (ignore the packet). If not set or if set to the empty value (e.g.,
TCP_FLAGS_DISPOSITION="") then TCP_FLAGS_DISPOSITION=DROP is assumed.
A_DROP and A_REJECT are audited versions of DROP and REJECT respectively and were added in Shorewall
4.4.20. They require AUDIT_TARGET in the kernel and iptables.
TCP_FLAGS_LOG_LEVEL=[log-level[:log-tag]]
Determines the syslog level for logging packets that fail the checks enabled by the tcpflags
interface option. The value must be a valid syslogd log level. If you don't want to log these
packets, set to the empty value (e.g., TCP_FLAGS_LOG_LEVEL="").
TRACK_PROVIDERS={Yes|No}
Added in Shorewall 4.4.3. When set to Yes, causes the track option to be assumed on all providers
defined in shorewall-providers[9](5). May be overridden on an individual provider through use of the
notrack option. The default value is 'No'.
Beginning in Shorewall 4.4.6, setting this option to 'Yes' also simplifies PREROUTING rules in
shorewall-tcrules[12](5). Previously, when TC_EXPERT=No, packets arriving through 'tracked' provider
interfaces were unconditionally passed to the PREROUTING tcrules. This was done so that tcrules could
reset the packet mark to zero, thus allowing the packet to be routed using the 'main' routing table.
Using the main table allowed dynamic routes (such as those added for VPNs) to be effective. The
rtrules file was created to provide a better alternative to clearing the packet mark. As a
consequence, passing these packets to PREROUTING complicates things without providing any real
benefit. Beginning with Shorewall 4.4.6, when TRACK_PROVIDERS=Yes and TC_EXPERT=No, packets arriving
through 'tracked' interfaces will not be passed to the PREROUTING rules. Since TRACK_PROVIDERS was
just introduced in 4.4.3, this change should be transparent to most, if not all, users.
TRACK_RULES={Yes|No|File}
Added in Shorewall 4.5.20. If set to Yes, causes the compiler to add a comment to iptables rules to
indicate the file name and line number of the configuration entry that generated the rule. If set to
No (the default), then no such comments are added.
Setting this option to Yes requires the Comments capability in iptables and kernel.
Beginning with Shorewall 5.0.5, the option may also be set to File. That setting causes similar
comments to be added to the .iptables-restore-input file, which is normally created in
/var/lib/shorewall.
UNTRACKED_DISPOSITION=[ACCEPT|A_ACCEPT|A_DROP|A_REJECT|DROP|REJECT|CONTINUE]
Added in Shorewall 4.5.13. Shorewall has traditionally passed UNTRACKED packets through the NEW
section of shorewall-rules[8] (5). When a packet in UNTRACKED state fails to match any rule in the
UNTRACKED section, the packet is disposed of based on this setting. The default value is CONTINUE for
compatibility with earlier versions.
UNTRACKED_LOG_LEVEL=log-level[:log-tag]
Added in Shorewall 4.5.13. Packets in the UNTRACKED state that do not match any rule in the UNTRACKED
section of shorewall-rules[8] (5) are logged at this level. The default value is empty which means no
logging is performed.
USE_DEFAULT_RT=[Yes|No]
When set to 'Yes', this option causes the Shorewall multi-ISP feature to create a set of routing
rules which are resilient to changes in the main routing table. Such changes can occur for a number
of reasons, VPNs going up and down being an example. The idea is to send packets through the main
table prior to applying any of the Shorewall-generated routing rules. So changes to the main table
will affect the routing of packets by default.
When USE_DEFAULT_RT=Yes:
1. Both the DUPLICATE and the COPY columns in providers[9](5) file must remain empty (or contain
"-").
2. The default route is added to the the 'default' table rather than to the main table.
3. If running Shorewall 5.1.0 or earlier or if BALANCE_PROVIDERS=Yes (Shorewall 5.1.1 or later),
then the balance provider option is assumed unless the fallback, loose, load or tproxy option is
specified.
4. Packets are sent through the main routing table by a rule with priority 999. In
shorewall-rtrules[30](5), the range 1-998 may be used for inserting rules that bypass the main
table.
5. All provider gateways must be specified explicitly in the GATEWAY column. detect may not be
specified..if n .sp
Note
detect may be specified for interfaces whose configuration is managed by dhcpcd. Shorewall
will use dhcpcd's database to find the interface's gateway.
6. You should disable all default route management outside of Shorewall. If a default route is added
to the main table while Shorewall is started, then all policy routing will stop working (except
for those routing rules in the priority range 1-998).
Prior to Shorewall 4.6.0, if USE_DEFAULT_RT was not set or if it was set to the empty string then
USE_DEFAULT_RT=No was assumed. Beginning with Shorewall 4.6.0, the default is USE_DEFAULT_RT=Yes and
use of USE_DEFAULT_RT=No is deprecated.
Warning
The enable, disable and reenable commands do not work correctly when USE_DEFAULT_RT=No.
USE_NFLOG_SIZE=[Yes|No]
Added in Shorewall 5.1.5. The second parameter to the NFLOG target specifies how many bytes of the
packet to copy to the log; if omitted or if supplied as zero, the entire packet is copied. This
feature has traditionally been implemented using the --nflog-range option to the NFLOG iptables
target. Unfortuntely, the --nflog-range option never worked (the entire packet was always copied). To
deal with this issue, the Netfilter team:
• Added a warning message when --nflog-range is used
• Added --nflog-size which works like --nflog-range was intended to work.
When USE_NFLOG_SIZE=Yes, Shorewall will attempt to use the new --nflog-size feature. If that feature
is not available in the running kernel and ip[6]tables, an error is raised.
When USE_NFLOG_SIZE is not supplied, USE_NFLOG_SIZE=No is assumed. When USE_NFLOG_SIZE is added by
shorewall update, it is added with setting No.
USE_PHYSICAL_NAMES=[Yes|No]
Added in Shorewall 4.4.27. Normally, when Shorewall creates a Netfilter chain that relates to an
interface, it uses the interface's logical name as the base of the chain name. For example, if the
logical name for an interface is OAKLAND, then the input chain for traffic arriving on that interface
would be 'OAKLAND_in'. If this option is set to Yes, then the physical name of the interface will be
used the base of the chain name.
USE_RT_NAMES=[Yes|No]
Added in Shorewall 4.5.15. When set to 'Yes', Shorewall will use routing table (provider) names in
the generated script rather than table numbers. When set to 'No' (the default), routing table numbers
will be used.
Caution
If you set USE_RT_NAMES=Yes and KEEP_RT_TABLES=Yes, then you must insure that all of your
providers have entries in /etc/iproute2/rt_tables as well as the following entries:
255 local
254 main
253 default
250 balance
0 unspec
Without these entries, the firewall will fail to start.
VERBOSE_MESSAGES=[Yes|No]
Added in Shorewall 5.0.9. When Yes (the default), messages produced by the ?INFO and ?WARNING
directives include the filename and linenumber of the directive. When set to No, that additional
information is omitted. The setting may be overridden on a directive by directive basis by following
?INFO or ?WARNING with '!' (no intervening white space).
VERBOSITY=[number]
Shorewall has traditionally been very noisy (produced lots of output). You may set the default level
of verbosity using the VERBOSITY OPTION.
Values are:
0 - Silent. You may make it more verbose using the -v
option
1 - Major progress messages displayed
2 - All progress messages displayed (pre Shorewall-3.2.0
behavior)
If not specified, then 2 is assumed.
WARNOLDCAPVERSION=[Yes|No]
Added in Shorewall 4.5.12. When set to Yes (the default), the compiler issues a warning when it finds
a capabilities file that doesn't specify all of the capabilities supported by the compiler. When
WARNOLDCAPVERSION is set to No, no warning is issued.
WORKAROUNDS=[Yes|No]
Added in Shorewall 4.6.11. Over time, there have been a number of changes in Shorewall that work
around defects in other products such as iptables and ipset. When WORKAROUNDS=Yes, these workarounds
are enabled; when WORKAROUNDS=No, they are disabled. If not specified or if specified as empty,
WORKAROUNDS=Yes is assumed.
Warning
Do not set WORKAROUNDS=Yes if you need to be able to use Shorewall-generated scripts (such as
created by the save command) built by Shorewall 4.4.7 or older.
ZERO_MARKS=[Yes|No]
Added in Shorewall 5.0.12, this is a workaround for an issue where packet marks are not zeroed by the
kernel. It should be set to No (the default) unless you find that incoming packets are being
mis-routed for no apparent reasons.
Caution
Do not set this option to Yes if you have IPSEC software running on the firewall system.
ZONE_BITS=[number]
Added in Shorewall 4.4.26. When non-zero, enables automatic packet marking by source zone and
determines the number of bits in the 32-bit packet mark to be used for the zone mark. Default value
is 0.
ZONE2ZONE=[2|-]
Added in Shorewall 4.4.4. This option determines how Shorewall constructs chain names involving zone
names and/or 'all'. Beginning with Shorewall 4.6.0, the default is '-' (e.g., fw-net); prior to that
release, the default was '2' (e.g., fw2net).
FILES
/etc/shorewall/shorewall.conf
/etc/shorewall6/shorewall6.conf
SEE ALSO
shorewall(8)
NOTES
1. shorewall-policy
https://shorewall.org/manpages/shorewall-policy.html
2. shorewall-accounting
https://shorewall.org/manpages/shorewall-accounting.html
3. shorewall-nat
https://shorewall.org/manpages/shorewall-nat.html
4. shorewall-masq
https://shorewall.org/manpages/shorewall-masq.html
5. shorewall-routestopped
https://shorewall.org/manpages/shorewall-routestopped.html
6. shorewall-stoppedrules
https://shorewall.org/manpages/shorewall-stoppedrules.html
7. shorewall-conntrack
https://shorewall.org/manpages/shorewall-conntrack.html
8. shorewall-rules
https://shorewall.org/manpages/shorewall-rules.html
9. shorewall-providers(5)
https://shorewall.org/manpages/shorewall-providers.html
10. shorewall-tcfilters(5)
https://shorewall.org/manpages/shorewall-tcfilters.html
11. shorewall-blrules
https://shorewall.org/manpages/shorewall-blrules.html
12. shorewall-tcrules
https://shorewall.org/manpages/shorewall-tcrules.html
13. Shorewall6
https://shorewall.org/IPv6Support.html
14. https://shorewall.org/Docker.html
https://shorewall.org/Docker.html
15. https://shorewall.org/ISO-3661.html
https://shorewall.org/ISO-3661.html
16. shorewall-zones
https://shorewall.org/manpages/shorewall-zones.html
17. shorewall-nesting
https://shorewall.org/manpages/shorewall-nesting.html
18. shorewall(8)
https://shorewall.org/manpages/shorewall.html
19. shorewall-params(5)
https://shorewall.org/manpages/shorewall-params.html
20. shorewall-interfaces
https://shorewall.org/manpages/shorewall-interfaces.html
21. shorewall-logging(8)
https://shorewall.org/manpages/shorewall-logging.html
22. shorewall-maclist
https://shorewall.org/manpages/shorewall-maclist.html
23. shorewall[6].conf
https://shorewall.org/manpages/shorewall.conf.html
24. https://shorewall.org/MultiISP.html#null_routing
https://shorewall.org/MultiISP.html#null_routing
25. Shorewall Init Package
https://shorewall.org/manpages/shorewall-init.html
26. Hairpin packets are packets that are routed out of the same interface that they arrived on.
27. Hairpin packets are packets that are routed out of the same interface that they arrived on.
28. shorewall-tcinterfaces
https://shorewall.org/manpages/shorewall-tcinterfaces.html
29. shorewall-tcpri
https://shorewall.org/manpages/shorewall-tcpri.html
30. shorewall-rtrules
https://shorewall.org/manpages/shorewall-rtrules.html
Configuration Files 09/24/2020 SHOREWALL.CONF(5)