Provided by: shorewall6_4.4.26.1-1_all bug


       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). If the value contains
       shell metacharacters or white-space, then it must be enclosed in
       quotes. Example: LOG_LEVEL="NFLOG(1,0,1)".


       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.





           To allow for default rules to be applied when USE_ACTIONS=No, the
           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

           The value applied to these may be:
               a) The name of an
               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[1](5).

           Added in Shorewall 4.4.7. If set to Yes, Shorewall6 accounting is
           enabled (see shorewall6-accounting[2](5)). If not specified or set
           to the empty value, ACCOUNTING=Yes is assumed.

           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

           The value of this variable affects Shorewall6's stopped state. When
           ADMINISABSENTMINDED=No, only traffic to/from those addresses listed
           in shorewall6-routestopped[4](5) is accepted when Shorewall6 is
           stopped. When ADMINISABSENTMINDED=Yes, in addition to traffic
           to/from addresses in shorewall6-routestopped[4](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

           If set, the behavior of the start and restart commands is change;
           if no files in /etc/shorewall have been changed since the last
           successful start or restart command, then the compilation step is
           skipped and the compiled script that executed the last start or
           restart command is used. The default is AUTOMAKE=No.

           The setting of the AUTOMAKE option is ignored if the start or
           restart command includes a directory name (e.g., shorewall6 restart

           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. The BLACKLIST_DISPOSITION setting has no effect on entries
           in the BLACKLIST section of shorewall6-rules[5] (5). It determines
           the disposition of packets sent to the blacklog target of

           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. The BLACKLIST_LOGLEVEL setting has no effect on entries in
           the BLACKLIST section of shorewall6-rules[5] (5). It determines the
           log level of packets sent to the blacklog target of

           When set to Yes or yes, blacklists are only consulted for new
           connections. This includes entries in the shorewall-blrules[7] (5)
           file and in the BLACKLIST section of shorewall6-rules[5] (5).

           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

           Important: This option requires CONFIG_IP_NF_TARGET_TCPMSS in your

           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[8](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[9](5), then you will want CLEAR_TC=No in
               this file.

           Added in Shorewall6 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 Shorewall6 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.

           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

           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.

           Added in Shorewall 4.4.7. When set to No or no, dynamic
           blacklisting using the shorewall6 drop, shorewall6 reject,
           shorewall6 logdrop and shorewall6 logreject is disabled. Default is

           Normally, when the SOURCE or DEST columns in shorewall-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

               #SOURCE DEST POLICY LOG
               #                   LEVEL
               net     all  DROP   info

           then the chain name is 'net2all' 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.

           Added in Shorewall 4.4.17. When set to Yes when compiling for use
           by Shorewall6 Lite (shorewall6 load, shorewall6 reload or
           shorewall6 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/shorewall6 but will copy the found
           in another location on the CONFIG_PATH.

           When compiling for direct use by Shorewall6, 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.

           Deprecated beginning with Shorewall 4.4.17.

           Beginning with Shorewall 4.4.17, the variables set in the 'params'
           file at compile time are available at run time with
           EXPORTPARAMS=No. As a consequence, beginning with that version the
           recommended setting is EXPORTPARAMS=No.

           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

           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 which is the recommended setting
           unless you are running Shorewall6 Lite.

           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](5).

               FASTACCEPT=Yes is incompatible with BLACKLISTNEWONLY=No.

           Added in Shorewall 4.4.11 Beta 3. 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.

           Deprecated in Shorewall 4.4.26 in favor of PROVIDER_OFFSET.

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

           The width of the fields are determined by the setting of the
           WIDE_TC_MARKS option.

           When WIDE_TC_MARKS=No (the default):

            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.

           When WIDE_TC_MARKS=Yes:

            1. The MARK field in the providers file must have a value that is
               a multiple of 65536 (using hex representation, the values are
               0x010000-0xFF0000 with the low-order 16 bits being zero).

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

            3. Marks used for traffic shaping must be in the range of 1-16383
               and may still not be set in the PREROUTING chain.

           Regardless of the setting of WIDE_TC_MARKS, when you SAVE or
           RESTORE in tcrules, only the TC mark value is saved or restored.
           Shorewall handles saving and restoring the routing (provider)

           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[10](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[11](5). With IMPLICIT_CONTINUE=Yes, that happens

           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).

           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.

           This rather useless parameter determines whether Shorewall6 enables
           or disables IPV6 Packet Forwarding on all interfaces
           (/proc/sys/net/ipv6/config/all/forwarding). 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

           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.

           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.

           Added in Shorewall6 4.4.20. If not specified, the default is Yes
           which preserves the legacy behavior of start -f (the modification
           times of the files in /etc/shorewall6 are compare with that of
           /var/lib/shorewall6/restore). If set to No, then the times are
           compared with that of /var/lib/shorewall6/firewall, which is
           consistant with the way that restart -f works.

           Added in Shorewall 4.4.7. When set to Yes, restricts the set of
           modules loaded by shorewall to those listed in
           /var/lib/shorewall6/helpers and those that are actually used. When
           not set, or set to the empty value, LOAD_HELPERS_ONLY=No is

           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.

               The setting of LOGFORMAT has an effect of the permitted length
               of zone names. See shorewall6-zones[10] (5).

           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.

           Deprecated in Shorewall 4.4.12.

           As of Shorewall 4.4.12, these parameters are Deprecated.

           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. If you
           supply one of these, then you should also supply the other.



           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, 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.

           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 ip6tables.

           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.

           The performance of configurations with a large numbers of entries
           in shorewall-maclist[12](5) can be improved by setting the
           MACLIST_TTL variable in shorewall.conf[13](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[12](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).

           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

           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.

           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). 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,      TC_BITS=8,
           WIDE_TC_MARKS=No,      TC_BITS=8, PROVIDER_BITS=8,
           WIDE_TC_MARKS=Yes,     TC_BITS=14, PROVIDER_BITS=8,
           WIDE_TC_MARKS=Yes,     TC_BITS=14, PROVIDER_BITS=8,

       MODULE_SUFFIX=["extension ..."]
           The value of this option determines the possible file extensions of
           kernel modules. The default value is "ko ko.gz o o.gz gz".

           This parameter specifies the directory/directories where your
           kernel netfilter modules may be found. If you leave the variable
           empty, Shorewall6 will supply "/lib/modules/`uname

           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

           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.

           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.

           ·   Optimization category 1 - Traditionally, Shorewall has created
               rules for the complete matrix of host groups defined by the
               zones, interfaces and hosts files[14]. 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

               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.

           ·   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
               preceed the final blanket ACCEPT rule in the chain are now

           ·   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

               ·   accounting chains (unless OPTIMIZE_ACCOUNTING=Yes)

               ·   action chains (user-defined)

               ·   'blacklst' chain

               ·   dynamic


               ·   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

               ·   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.

           ·   Optimization category 8 - Added in Shorewall 4.4.9. When set,
               causes chains with identical rules to be collapsed into a
               single chain.

           ·   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 combatible rules is often generated when macros
               are invoked in sequence.

               The ability to combine adjacent rules is limited by two

               ·   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
                   concatinated comment reaches 255 characters.

               When either of these limits would be exceeded, the current
               combined rule is emitted and the compiler attemts 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'.

               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 reult in
                   the combined comment "Others and FOO, BAR". Note: Optimize
                   level 16 requires "Extended Multi-port Match" in your
                   iptables and kernel.

           The default value is zero which disables all optimizations.

           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

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

           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 Shorewall6 falls back to /usr/bin/perl/

           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.

           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
           ZONE_BITS must be < 32. See MASK_BITS above for default value.


           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:.RS 4
       The default values for these are as follows:.RS 4 RSH_COMMAND: ssh
       ${root}@${system} ${command}
           RCP_COMMAND: scp ${files}
       Shell variables that will be set when the commands are envoked are as
       follows:.RS 4 root - root user. Normally
                     root but may be overridden using the '-r'
           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
                         firewall system.
           destination - The directory
                         on the remote system that the files are to be copied

           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[15].

           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

           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.

           Added in Shorewall 4.4.20. The default setting is DROP which causes
           smurf packets (see the nosmurfs option in
           shorewall-interfaces[16](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 ip6tables.

           Specifies the logging level for smurf packets (see the nosmurfs
           option in shorewall6-interfaces[17](5)). If set to the empty value
           ( SMURF_LOG_LEVEL="" ) then smurfs are not logged.

           Added in Shorewall 4.4.20. Determines the disposition of packets
           matching the filter option (see shorewall6-interfaces[17](5)) and
           of hairpin packets on interfaces without the routeback option.[18]
           interfaces without the routeback option.

           Added on Shorewall 4.4.20. Determines the logging of packets
           matching the filter option (see shorewall6-interfaces[17](5)) and
           of hairpin packets on interfaces without the routeback option.[19]
           interfaces without the routeback option. The default is info. If
           you don't wish for these packets to be logged, use

           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 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.

           Added in Shorewall 4.4.26. 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.

           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.

           Beginning with Shorewall 4.4.15, if you set TC_ENABLED=Shared or
           shared, then you should create symbolic links from your Shorewall6
           configuration directory (normally /etc/shorewall6/) to your
           Shorewall tcdevices and tcclasses files. This allows the compiler
           to have access to your Shorewall traffic shaping configuration so
           that it can validate CLASSIFY rules in shorewall6-tcrules[20] (5).

               If you also run Shorewall and if you have TC_ENABLED=Internal
               in your shorewall-conf[9](5), then you will want TC_ENABLED=No
               or TC_ENABLED=Shared 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

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

           Added in Shorewall 4.4.6. Determines the mapping of a packet's TOS
           field to priority bands. See shorewall6-tcpri[22](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

           Determines the disposition of TCP packets that fail the checks
           enabled by the tcpflags interface option (see
           shorewall6-interfaces[17](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.,

           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="").

           Added in Shorewall 4.4.3. When set to Yes, causes the track option
           to be assumed on all providers defined in
           shorewall6-providers[21](5). May be overridden on an individual
           provider through use of the notrack option. The default value is

           Beginning in Shorewall 4.4.6, setting this option to 'Yes' also
           simplifies PREROUTING rules in shorewall6-tcrules[8](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
           shorewall6-route_rules[23](5) 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.

           Added in Shorewall6 4.4.25. When set to 'Yes', this option causes
           the Shorewall6 multi-ISP feature to create a different 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 Shorewall6-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
               shorewall6-providers[21](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. balance is assumed unless loose is specified.

            4. Packets are sent through the main routing table by a rule with
               priority 999. In shorewall6-routing_rules[24](5), the range
               1-998 may be used for inserting rules that bypass the main

            5. All provider gateways must be specified explicitly in the
               GATEWAY column.  detect may not be specified.

            6. You should disable all default route management outside of
               Shorewall6. 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).

           If USE_DEFAULT_RT is not set or if it is set to the empty string
           then USE_DEFAULT_RT=No is assumed.

           Shorewall6 has traditionally been very noisy (produced lots of
           output). You may set the default level of verbosity using the

           Values are:
               0 - Silent. You may make it more verbose using the -v
               1 - Major progress messages displayed
               2 - All progress messages displayed (pre Shorewall6-3.2.0
           If not specified, then 2 is assumed.

           Deprecated in Shorewall 4.4.26 in favor of TC_BITS and MASK_BITS.

           When set to No (the default), traffic shaping marks are 8 bytes
           wide (possible values are 1-255). When WIDE_TC_MARKS=Yes, traffic
           shaping marks are 14 bytes wide (values 1-16383). The setting of
           WIDE_TC_MARKS also has an effect on the HIGH_ROUTE_MARKS option
           (see above).

           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

           Added in Shorewall 4.4.4. This option determines how Shorewall
           constructs chain names involving zone names and/or 'all'. The
           default is '2' (e.g., fw2net).




       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),
       shoewall6-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),


        1. shorewall6-policy

        2. shorewall6-accounting

        3. shorewall-accounting

        4. shorewall6-routestopped

        5. shorewall6-rules

        6. shorewall6-blrules

        7. shorewall-blrules

        8. shorewall6-tcrules

        9. shorewall-conf

       10. shorewall6-zones

       11. shorewall6-nesting

       12. shorewall-maclist

       13. shorewall.conf

       14. the complete matrix of host groups defined by the zones, interfaces
           and hosts files

       15. Shorewall Init Package

       16. shorewall-interfaces

       17. shorewall6-interfaces

       18. Hairpin packets are packets that are routed out of the same
           interface that they arrived on.

       19. Hairpin packets are packets that are routed out of the same
           interface that they arrived on.

       20. shorewall6-tcrules

       21. shorewall6-providers

       22. shorewall6-tcpri

       23. shorewall6-route_rules

       24. shorewall6-routing_rules

[FIXME: source]                   12/13/2011                SHOREWALL6.CONF(5)