shorewall6.conf — Shorewall6 global configuration file




This file sets options that apply to Shorewall6 as a whole.

The file consists of Shell comments (lines beginning with '#'), blank lines and assignment statements (variable=value).


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 Shorewall6 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 Shorewall6 logging, a level of 6 (info) is appropriate. Shorewall6 log messages are generated by NetFilter and are logged using facility 'kern' and the level that you specifify. 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 NFLOG target support, you may also specify a log level of NFLOG (must be all caps). Rather than log its messages to syslogd, Shorewall6 will direct netfilter to log the messages via the 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). Ulogd is also available from and can be configured to log all Shorewall6 message to their own log file

The following options may be set in shorewall6.conf.






In earlier Shorewall6 versions, a "default action" for DROP and REJECT policies was specified in the file /usr/share/shorewall6/actions.std.

To allow for default rules to be applied when USE_ACTIONS=No, the DROP_DEFAULT, REJECT_DEFAULT, ACCEPT_DEFAULT, QUEUE_DEFAULT and NFQUEUE_DEFAULT options have been 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.
b) The name of a macro (Shorewall6-shell only)
c) None or none

The default values are:


If USE_ACTIONS=Yes, then these values refer to action.Drop and action.Reject respectively. If USE_ACTIONS=No, then these values refer to macro.Drop and macro.Reject.

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 shorewall6-policy(5).


The value of this variable affects Shorewall6's stopped state. When ADMINISABSENTMINDED=No, only traffic to/from those addresses listed in shorewall6-routestopped(5) is accepted when Shorewall6 is stopped. When ADMINISABSENTMINDED=Yes, in addition to traffic to/from addresses in shorewall6-routestopped(5), connections that were active when Shorewall6 stopped continue to work and all new connections from the firewall system itself are allowed. If this variable is not set or is given the empty value then ADMINISABSENTMINDED=No is assumed.


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>". The AUTO_COMMENT option has a default value of 'Yes'.


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.


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_LOGLEVEL=debug). If you do not assign a value or if you assign an empty value then packets from blacklisted hosts are not logged.


When set to Yes or yes, blacklists are only consulted for new connections. When set to No or no, blacklists are consulted for every packet (will slow down your firewall noticably if you have large blacklists). If the BLACKLISTNEWONLY option is not set or is set to the empty value then BLACKLISTNEWONLY=No is assumed.


BLACKLISTNEWONLY=No is incompatible with FASTACCEPT=Yes.


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.


If this option is set to No then Shorewall6 won't clear the current traffic control rules during [re]start. This setting is intended for use by people that 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/shorewall6/tcstart file. That way, your traffic shaping rules can still use the “fwmark” classifier based on packet marking defined in shorewall6-tcrules(5). If not specified, CLEAR_TC=No is assumed.


If you also run Shorewall and if you have TC_ENABLED=Internal in your shorewall-conf(5), then you will want CLEAR_TC=No in this file.


Specifies where configuration files other than shorewall6.conf may be found. CONFIG_PATH is specifies as a list of directory names separated by colons (":"). When looking for a configuration file other than shorewall6.conf:

  • If the command is "try" or a "<configuration directory>" was specified in the command (e.g., shorewall6 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/shorewall6/configpath are used. As released from, that file sets the CONFIG_PATH to /etc/shorewall6:/usr/share/shorewall6:/usr/share/shorewall but your particular distribution may set it differently. See the output of shorewall6 show config for the default on your system.

Note that the setting in /usr/share/shorewall6/configpath is always used to locate shorewall6.conf.


If set to Yes (the default value), entries in the /etc/shorewall6/route_stopped 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.


Causes Shorewall6 to not load the listed kernel modules.


Normally, when the SOURCE or DEST columns in shorewall6-policy(5) contains 'all', a single policy chain is created and the policy is enforced in that chain. For example, if the policy entry is

#                   LEVEL
net     all  DROP   info

then the chain name is 'net2all' which is also the chain named in Shorewall6 log messages generated as a result of the policy. If EXPAND_POLICIES=Yes, then Shorewall6 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.


It is quite difficult to code a 'params' file that assigns other than constant values such that it works correctly with Shorewall6 Lite. The EXPORTPARAMS option works around this problem. When EXPORTPARAMS=No, the 'params' file is not copied to the compiler output.

With EXPORTPARAMS=No, if you need to set environmental variables on the firewall system for use by your extension scripts, then do so in the init extension script.

The default is EXPORTPARAMS=Yes


Normally, Shorewall6 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 'loc2net' chain.

If you set FASTACCEPT=Yes, then ESTABLISHED/RELEATED 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 shorewall6-rules(5).


FASTACCEPT=Yes is incompatible with BLACKLISTNEWONLY=No.


You may set HIGH_ROUTE_MARKS=Yes in to effectively divide the packet mark and connection mark into two 8-byte mark fields.

When you do this:

  1. The MARK field in the providers file must have a value that is less than 65536 and that is a multiple of 256 (using hex representation, the values are 0x0100-0xFF00 with the low-order 8 bits being zero).

  2. You may only set those mark values in the PREROUTING chain.

  3. Marks used for traffic shaping must still be in the range of 1-255 and may still not be set in the PREROUTING chain.

  4. When you SAVE or RESTORE in tcrules, only the TC mark value is saved or restored. Shorewall6 handles saving and restoring the routing (provider) marks.


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 shorewall6-zones(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 shorewall6-nesting(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).


This parameter determines whether Shorewall6 enables or disables IPV4 Packet Forwarding (/proc/sys/net/ipv4/ip_forward). Possible values are:

On or on

packet forwarding will be enabled.

Off or off

packet forwarding will be disabled.

Keep or keep

Shorewall6 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.


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.


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, refresh, restore on restart command.

The default is KEEP_RT_TABLES=No.


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.


This option is intended for use as a debugging aid. When set to a log level, this option causes Shorewall6 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:



To help insure that all packets in the NEW state are logged, rate limiting (LOGBURST and LOGRATE) 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.


Do not use this option if the resulting log messages will be sent to another system.


This parameter tells the /sbin/shorewall6 program where to look for Shorewall6 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.


The value of this variable generate the --log-prefix setting for Shorewall6 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 “Shorewall6:%s:%s:” is assumed.



These parameters set the match rate and initial burst size for logged packets. Please see ip6tables(8) for a description of the behavior of these parameters (the ip6tables option --limit is set by LOGRATE and --limit-burst is set by LOGBURST). If both parameters are set empty, no rate-limiting will occur.



For each logging rule, the first time the rule is reached, the packet will be logged; in fact, since the burst is 5, the first five packets will be logged. After this, it will be 6 seconds (1 minute divided by the rate of 10) before a message will be logged from the rule, regardless of how many packets reach it. Also, every 6 seconds which passes without matching a packet, one of the bursts will be regained; if no packets hit the rule for 30 seconds, the burst will be fully recharged; back where we started.


Using the default LOGFORMAT, chain names may not exceed 11 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.


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.


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="").


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 with MACLIST_TABLE=mangle.


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 /sbin/shorewall6 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.

MODULE_SUFFIX=["extension ..."]

The value of this option determines the possible file extensions of kernel modules. The default value is "o gz ko o.gz".


This parameter specifies the directory/directories where your kernel netfilter modules may be found. If you leave the variable empty, Shorewall6 will supply the value "/lib/modules/`uname -r`/kernel/net/ipv4/netfilter" in versions of Shorewall6 prior to 3.2.4 and "/lib/modules/`uname -r`/kernel/net/ipv4/netfilter:/lib/modules/`uname -r`/kernel/net/ipv4/netfilter" in later versions.


The value of this variable determines the number of seconds that programs will wait for exclusive access to the Shorewall6 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 shorewall6 restart command.


Traditionally, Shorewall6 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 OPTIMIZE=1.

The OPTIMIZE 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.


Determines the order in which Shorewall6 searches directories for executable files.



Eariler generations of Shorewall6 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 shorewall6.conf:


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 envoked 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.

Specifies the simple name of a file in /var/lib/shorewall6 to be used as the default restore script in the shorewall6 save, shorewall6 restore, shorewall6 forget and shorewall6 -f start commands.


If SAVE_IPSETS=Yes, then the current contents of your ipsets will be saved by the shorewall6 save command. Regardless of the setting of SAVE_IPSETS, if saved ipset contents are available then they will be restored by shorewall6 restore.


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.


Specifies the logging level for smurf packets (see the nosmurfs option in shorewall6-interfaces(5)). If set to the empty value ( SMURF_LOG_LEVEL="" ) then smurfs are not logged.


Determines if Shorewall6 is allowed to start. As released from, this option is set to No. When set to Yes or yes, Shorewall6 may be started. Used as a guard against Shorewall6 being accidentally started before it has been configured.


If specified, determines where Shorewall6 will log the details of each start, restart and refresh command. Logging verbosity is determined by the setting of LOG_VERBOSITY above.


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 Shorewall6 to work with your distribution's initscripts. For RedHat, this should be set to /var/lock/subsys/shorewall6. For Debian, the value is /var/lock/shorewall6 and in LEAF it is /var/run/shorwall.


If you say Yes or yes here, Shorewall6 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=Internal or internal or leave the option empty then Shorewall6 will use its builtin traffic shaper (tc4shorewall6 written by Arne Bernin.


If you also run Shorewall and if you have TC_ENABLED=Internal in your shorewall-conf(5), then you will want TC_ENABLED=No in this file.


Normally, Shorewall6 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 shorewall6-providers(5).

If you know what you are doing, you can set TC_EXPERT=Yes and Shorewall6 will not include these cautionary checks.


Determines the disposition of TCP packets that fail the checks enabled by the tcpflags interface option (see shorewall6-interfaces(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.


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="").


Shorewall6 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 Shorewall6-3.2.0 behavior)

If not specified, then 2 is assumed.




shorewall6(8), shorewall6-accounting(5), shorewall6-actions(5), shorewall6-blacklist(5), shorewall6-hosts(5), shorewall6-interfaces(5), shorewall6-ipsec(5), shorewall6-maclist(5), shorewall6-masq(5), shorewall6-nat(5), shorewall6-netmap(5), shorewall6-params(5), shorewall6-policy(5), shorewall6-providers(5), shorewall6-proxyarp(5), shorewall6-route_rules(5), shorewall6-routestopped(5), shorewall6-rules(5), shorewall6-tcclasses(5), shorewall6-tcdevices(5), shorewall6-tcrules(5), shorewall6-tos(5), shorewall6-tunnels(5), shorewall6-zones(5)