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NAME

       rules - Shorewall rules file

SYNOPSIS

       /etc/shorewall/rules

DESCRIPTION

       Entries in this file govern connection establishment by defining
       exceptions to the policies layed out in shorewall-policy[1](5). By
       default, subsequent requests and responses are automatically allowed
       using connection tracking. For any particular (source,dest) pair of
       zones, the rules are evaluated in the order in which they appear in
       this file and the first terminating match is the one that determines
       the disposition of the request. All rules are terminating except LOG
       and COUNT rules.

           Warning
           If you masquerade or use SNAT from a local system to the internet,
           you cannot use an ACCEPT rule to allow traffic from the internet to
           that system. You must use a DNAT rule instead.

       The rules file is divided into sections. Each section is introduced by
       a "Section Header" which is a line beginning with SECTION and followed
       by the section name.

       Sections are as follows and must appear in the order listed:

       ESTABLISHED
           Packets in the ESTABLISHED state are processed by rules in this
           section.

           The only ACTIONs allowed in this section are ACCEPT, DROP, REJECT,
           LOG and QUEUE

           There is an implicit ACCEPT rule inserted at the end of this
           section.

       RELATED
           Packets in the RELATED state are processed by rules in this
           section.

           The only ACTIONs allowed in this section are ACCEPT, DROP, REJECT,
           LOG and QUEUE

           There is an implicit ACCEPT rule inserted at the end of this
           section.

       NEW
           Packets in the NEW, INVALID and UNTRACKED states are processed by
           rules in this section.

           Note
           If you are not familiar with Netfilter to the point where you are
           comfortable with the differences between the various connection
           tracking states, then it is suggested that you omit the ESTABLISHED
           and RELATED sections and place all of your rules in the NEW section
           (That's after the line that reads SECTION NEW').

           Warning
           If you specify FASTACCEPT=Yes in shorewall.conf[2](5) then the
           ESTABLISHED and RELATED sections must be empty.

       You may omit any section that you don't need. If no Section Headers
       appear in the file then all rules are assumed to be in the NEW section.

       When defining rules that rewrite the destination IP address and/or port
       number (namely DNAT and REDIRECT rules), it is important to keep
       straight which columns in the file specify the packet before rewriting
       and which specify how the packet will look after rewriting.

       ·   The DEST column specifies the final destination for the packet
           after rewriting and can include the final IP address and/or port
           number.

       ·   The remaining columns specify characteristics of the packet before
           rewriting. In particular, the ORIGINAL DEST column gives the
           original destination IP address of the packet and the DEST PORT(S)
           column give the original destination port(s).

       The columns in the file are as follows.

       ACTION -
       {ACCEPT[+|!]|NONAT|DROP[!]|REJECT[!]|DNAT[-]|REDIRECT[-]|CONTINUE[!]|LOG|QUEUE[!]|NFQUEUE[!]|COUNT[(queuenumber)]|COMMENT|action|macro[(target)]}[:{log-level|none}[!][:tag]]
           Specifies the action to be taken if the connection request matches
           the rule. Must be one of the following.

           ACCEPT
               Allow the connection request.

           ACCEPT+
               like ACCEPT but also excludes the connection from any
               subsequent matching DNAT[-] or REDIRECT[-] rules

           ACCEPT!
               like ACCEPT but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           NONAT
               Excludes the connection from any subsequent DNAT[-] or
               REDIRECT[-] rules but doesn't generate a rule to accept the
               traffic.

           DROP
               Ignore the request.

           DROP!
               like DROP but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           REJECT
               disallow the request and return an icmp-unreachable or an RST
               packet.

           REJECT!
               like REJECT but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           DNAT
               Forward the request to another system (and optionally another
               port).

           DNAT-
               Advanced users only.

               Like DNAT but only generates the DNAT iptables rule and not the
               companion ACCEPT rule.

           REDIRECT
               Redirect the request to a server running on the firewall.

           REDIRECT-
               Advanced users only.

               Like REDIRECT but only generates the REDIRECT iptables rule and
               not the companion ACCEPT rule.

           CONTINUE
               For experts only.

               Do not process any of the following rules for this (source
               zone,destination zone). If the source and/or destination IP
               address falls into a zone defined later in
               shorewall-zones[3](5) or in a parent zone of the source or
               destination zones, then this connection request will be passed
               to the rules defined for that (those) zone(s). See
               shorewall-nesting[4](5) for additional information.

           CONTINUE!
               like CONTINUE but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           LOG
               Simply log the packet and continue with the next rule.

           QUEUE
               Queue the packet to a user-space application such as ftwall
               (http://p2pwall.sf.net). The application may reinsert the
               packet for further processing.

           QUEUE!
               like QUEUE but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           NFQUEUE
               Queues the packet to a user-space application using the
               nfnetlink_queue mechanism. If a queuenumber is not specified,
               queue zero (0) is assumed.

           NFQUEUE!
               like NFQUEUE but exempts the rule from being suppressed by
               OPTIMIZE=1 in shorewall.conf[2](5).

           COUNT
               Simply increment the rule's packet and byte count and pass the
               packet to the next rule.

           COMMENT
               the rest of the line will be attached as a comment to the
               Netfilter rule(s) generated by the following entries. The
               comment will appear delimited by "/* ... */" in the output of
               "shorewall show <chain>". To stop the comment from being
               attached to further rules, simply include COMMENT on a line by
               itself.

           action
               The name of an action declared in shorewall-actions[5](5) or in
               /usr/share/shorewall/actions.std.

           macro
               The name of a macro defined in a file named macro.macro. If the
               macro accepts an action parameter (Look at the macro source to
               see if it has PARAM in the TARGET column) then the macro name
               is followed by the parenthesized target (ACCEPT, DROP, REJECT,
               ...) to be substituted for the parameter.

               Example: FTP(ACCEPT).

               The older syntax where the macro name and the target are
               separated by a slash (e.g. FTP/ACCEPT) is still allowed but is
               deprecated.

           The ACTION may optionally be followed by ":" and a syslog log level
           (e.g, REJECT:info or Web(ACCEPT):debug). This causes the packet to
           be logged at the specified level. Note that if the ACTION involves
           destination network address translation (DNAT, REDIRECT, etc.) then
           the packet is logged before the destination address is rewritten.

           If the ACTION names an action declared in shorewall-actions[5](5)
           or in /usr/share/shorewall/actions.std then:

           ·   If the log level is followed by "!' then all rules in the
               action are logged at the log level.

           ·   If the log level is not followed by "!" then only those rules
               in the action that do not specify logging are logged at the
               specified level.

           ·   The special log level none!  suppresses logging by the action.

           You may also specify ULOG or NFLOG (must be in upper case) as a log
           level.This will log to the ULOG or NFLOG target for routing to a
           separate log through use of ulogd
           (http://www.netfilter.org/projects/ulogd/index.html).

           Actions specifying logging may be followed by a log tag (a string
           of alphanumeric characters) which is appended to the string
           generated by the LOGPREFIX (in shorewall.conf[2](5)).

           Example: ACCEPT:info:ftp would include 'ftp ' at the end of the log
           prefix generated by the LOGPREFIX setting.

       SOURCE -
       {zone|{all|any}[+][-]}[:interface][:{address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset}
           Source hosts to which the rule applies. May be a zone declared in
           /etc/shorewall/zones, $FW to indicate the firewall itself, all,
           all+, all-, all+- or none.

           When none is used either in the SOURCE or DEST column, the rule is
           ignored.

           all means "All Zones", including the firewall itself.  all- means
           "All Zones, except the firewall itself". When all[-] is used either
           in the SOURCE or DEST column intra-zone traffic is not affected.
           When all+[-] is "used, intra-zone traffic is affected.

           Except when all[+][-] is specified, clients may be further
           restricted to a list of networks and/or hosts by appending ":" and
           a comma-separated list of network and/or host addresses. Hosts may
           be specified by IP or MAC address; mac addresses must begin with
           "~" and must use "-" as a separator.

           any is equivalent to all when there are no nested zones. When there
           are nested zones, any only refers to top-level zones (those with no
           parent zones).

           Hosts may also be specified as an IP address range using the syntax
           lowaddress-highaddress. This requires that your kernel and iptables
           contain iprange match support. If your kernel and iptables have
           ipset match support then you may give the name of an ipset prefaced
           by "+". The ipset name may be optionally followed by a number from
           1 to 6 enclosed in square brackets ([]) to indicate the number of
           levels of source bindings to be matched.

           You may exclude certain hosts from the set already defined through
           use of an exclusion (see shorewall-exclusion[6](5)).

           Examples:

           dmz:192.168.2.2
               Host 192.168.2.2 in the DMZ

           net:155.186.235.0/24
               Subnet 155.186.235.0/24 on the Internet

           loc:192.168.1.1,192.168.1.2
               Hosts 192.168.1.1 and 192.168.1.2 in the local zone.

           loc:~00-A0-C9-15-39-78
               Host in the local zone with MAC address 00:A0:C9:15:39:78.

           net:192.0.2.11-192.0.2.17
               Hosts 192.0.2.11-192.0.2.17 in the net zone.

           net:!192.0.2.11-192.0.2.17
               All hosts in the net zone except for 192.0.2.11-192.0.2.17.

           net:155.186.235.0/24!155.186.235.16/28
               Subnet 155.186.235.0/24 on the Internet except for
               155.186.235.16/28

       DEST -
       {zone|{all|any}[+][-]}[:{interface|address-or-range[,address-or-range]...[exclusion]|exclusion|+ipset}][:port[:random]]
           Location of Server. May be a zone declared in
           shorewall-zones[3](5), $FW to indicate the firewall itself, all.
           all+ or none.

           When none is used either in the SOURCE or DEST column, the rule is
           ignored.

           When all is used either in the SOURCE or DEST column intra-zone
           traffic is not affected. When all+ is used, intra-zone traffic is
           affected.

           any is equivalent to all when there are no nested zones. When there
           are nested zones, any only refers to top-level zones (those with no
           parent zones).

           The zone should be omitted in DNAT-, REDIRECT- and NONAT rules.

           If the DEST zone is a bport zone, then either:

            1. the SOURCE must be all[+][-], or

            2. the SOURCE zone must be another bport zone associated with the
               same bridge, or

            3. the SOURCE zone must be an ipv4 zone that is associated with
               only the same bridge.

           Except when all[+]|[-] is specified, the server may be further
           restricted to a particular network, host or interface by appending
           ":" and the network, host or interface. See SOURCE above.

           You may exclude certain hosts from the set already defined through
           use of an exclusion (see shorewall-exclusion[6](5)).

           Restrictions:

           1. MAC addresses are not allowed (this is a Netfilter restriction).

           2. You may not specify both an interface and an address.

           Like in the SOURCE column, you may specify a range of IP addresses
           using the syntax lowaddress-highaddress. When the ACTION is DNAT or
           DNAT-, the connections will be assigned to addresses in the range
           in a round-robin fashion.

           If you kernel and iptables have ipset match support then you may
           give the name of an ipset prefaced by "+". The ipset name may be
           optionally followed by a number from 1 to 6 enclosed in square
           brackets ([]) to indicate the number of levels of destination
           bindings to be matched. Only one of the SOURCE and DEST columns may
           specify an ipset name.

           The port that the server is listening on may be included and
           separated from the server's IP address by ":". If omitted, the
           firewall will not modifiy the destination port. A destination port
           may only be included if the ACTION is DNAT or REDIRECT.

           Example:
               loc:192.168.1.3:3128 specifies a local server at IP address
               192.168.1.3 and listening on port 3128.

           The port may be specified as a service name. You may specify a port
           range in the form lowport-highport to cause connections to be
           assigned to ports in the range in round-robin fashion. When a port
           range is specified, lowport and highport must be given as integers;
           service names are not permitted. Additionally, the port range may
           be optionally followed by :random which causes assignment to ports
           in the list to be random.

           If the ACTION is REDIRECT or REDIRECT-, this column needs only to
           contain the port number on the firewall that the request should be
           redirected to. That is equivalent to specifying $FW::port.

       PROTO (Optional) -
       {-|tcp:syn|ipp2p|ipp2p:udp|ipp2p:all|protocol-number|protocol-name|all}
           Protocol - ipp2p* requires ipp2p match support in your kernel and
           iptables.  tcp:syn implies tcp plus the SYN flag must be set and
           the RST,ACK and FIN flags must be reset.

       DEST PORT(S) (Optional) -
       {-|port-name-number-or-range[,port-name-number-or-range]...}
           Destination Ports. A comma-separated list of Port names (from
           services(5)), port numbers or port ranges; if the protocol is icmp,
           this column is interpreted as the destination icmp-type(s). ICMP
           types may be specified as a numeric type, a numberic type and code
           separated by a slash (e.g., 3/4), or a typename. See
           http://www.shorewall.net/configuration_file_basics.htm#ICMP.

           If the protocol is ipp2p, this column is interpreted as an ipp2p
           option without the leading "--" (example bit for bit-torrent). If
           no port is given, ipp2p is assumed.

           A port range is expressed as lowport:highport.

           This column is ignored if PROTO = all but must be entered if any of
           the following columns are supplied. In that case, it is suggested
           that this field contain a dash (-).

           If your kernel contains multi-port match support, then only a
           single Netfilter rule will be generated if in this list and the
           CLIENT PORT(S) list below:

           1. There are 15 or less ports listed.

           2. No port ranges are included or your kernel and iptables contain
           extended multiport match support.

       SOURCE PORT(S) (Optional) -
       {-|port-name-number-or-range[,port-name-number-or-range]...}
           Port(s) used by the client. If omitted, any source port is
           acceptable. Specified as a comma- separated list of port names,
           port numbers or port ranges.

               Warning
               Unless you really understand IP, you should leave this column
               empty or place a dash (-) in the column. Most people who try to
               use this column get it wrong.
           If you don't want to restrict client ports but need to specify an
           ORIGINAL DEST in the next column, then place "-" in this column.

           If your kernel contains multi-port match support, then only a
           single Netfilter rule will be generated if in this list and the
           DEST PORT(S) list above:

           1. There are 15 or less ports listed.

           2. No port ranges are included or your kernel and iptables contain
           extended multiport match support.

       ORIGINAL DEST (Optional) -
       [-|address[,address]...[exclusion]|exclusion]
           If ACTION is DNAT[-] or REDIRECT[-] then if this column is included
           and is different from the IP address given in the DEST column, then
           connections destined for that address will be forwarded to the IP
           and port specified in the DEST column.

           A comma-separated list of addresses may also be used. This is most
           useful with the REDIRECT target where you want to redirect traffic
           destined for particular set of hosts. Finally, if the list of
           addresses begins with "!" (exclusion) then the rule will be
           followed only if the original destination address in the connection
           request does not match any of the addresses listed.

           For other actions, this column may be included and may contain one
           or more addresses (host or network) separated by commas. Address
           ranges are not allowed. When this column is supplied, rules are
           generated that require that the original destination address
           matches one of the listed addresses. This feature is most useful
           when you want to generate a filter rule that corresponds to a DNAT-
           or REDIRECT- rule. In this usage, the list of addresses should not
           begin with "!".

           It is also possible to specify a set of addresses then exclude part
           of those addresses. For example, 192.168.1.0/24!192.168.1.16/28
           specifies the addresses 192.168.1.0-182.168.1.15 and
           192.168.1.32-192.168.1.255. See shorewall-exclusion[6](5).

           See http://shorewall.net/PortKnocking.html[7] for an example of
           using an entry in this column with a user-defined action rule.

       RATE LIMIT (Optional) - [-|[{s|d}:[[name]:]]]rate/{sec|min}[:burst]
           You may rate-limit the rule by placing a value in this column:

           rate is the number of connections per interval (sec or min) and
           burst is the largest burst permitted. If no burst is given, a value
           of 5 is assumed. There may be no no whitespace embedded in the
           specification.

           Example: 10/sec:20

           When s: or d: is specified, the rate applies per source IP address
           or per destination IP address respectively. The name may be chosen
           by the user and specifies a hash table to be used to count matching
           connections. If not give, the name shorewallN (where N is a unique
           integer) is assumed. Where more than one rule specifies the same
           name, the connections counts for the rules are aggregated and the
           individual rates apply to the aggregated count.

           Example: s:ssh:3/min:5

       USER/GROUP (Optional) -
       [!][user-name-or-number][:group-name-or-number][+program-name]
           This column may only be non-empty if the SOURCE is the firewall
           itself.

           When this column is non-empty, the rule applies only if the program
           generating the output is running under the effective user and/or
           group specified (or is NOT running under that id if "!" is given).

           Examples:

           joe
               program must be run by joe

           :kids
               program must be run by a member of the 'kids' group

           !:kids
               program must not be run by a member of the 'kids' group

           +upnpd
               program named upnpd

                   Important
                   The ability to specify a program name was removed from
                   Netfilter in kernel version 2.6.14.

       MARK - [!]value[/mask][:C]
           Defines a test on the existing packet or connection mark. The rule
           will match only if the test returns true.

           If you don't want to define a test but need to specify anything in
           the following columns, place a "-" in this field.

           !
               Inverts the test (not equal)

           value
               Value of the packet or connection mark.

           mask
               A mask to be applied to the mark before testing.

           :C
               Designates a connection mark. If omitted, the packet mark's
               value is tested.

       CONNLIMIT - [!]limit[:mask]
           May be used to limit the number of simultaneous connections from
           each individual host to limit connections. Requires connlimit match
           in your kernel and iptables. While the limit is only checked on
           rules specifying CONNLIMIT, the number of current connections is
           calculated over all current connections from the SOURCE host. By
           default, the limit is applied to each host but can be made to apply
           to networks of hosts by specifying a mask. The mask specifies the
           width of a VLSM mask to be applied to the source address; the
           number of current connections is then taken over all hosts in the
           subnet source-address/mask. When !  is specified, the rule matches
           when the number of connection exceeds the limit.

       TIME - timeelement[&timelement...]
           May be used to limit the rule to a particular time period each day,
           to particular days of the week or month, or to a range defined by
           dates and times. Requires time match support in your kernel and
           iptables.

           timeelement may be:

           timestart=hh:mm[:ss]
               Defines the starting time of day.

           timestop=hh:mm[:ss]
               Defines the ending time of day.

           utc
               Times are expressed in Greenwich Mean Time.

           localtz
               Times are expressed in Local Civil Time (default).

           weekdays=ddd[,ddd]...
               where ddd is one of Mon, Tue, Wed, Thu, Fri, Sat or Sun

           monthdays=dd[,dd],...
               where dd is an ordinal day of the month

           datestart=yyyy[-mm[-dd[Thh[:mm[:ss]]]]]
               Defines the starting date and time.

           datestop=yyyy[-mm[-dd[Thh[:mm[:ss]]]]]
               Defines the ending date and time.

EXAMPLES

       Example 1:
           Accept SMTP requests from the DMZ to the internet

                        #ACTION SOURCE  DEST PROTO      DEST    SOURCE  ORIGINAL
                        #                               PORT    PORT(S) DEST
                        ACCEPT  dmz     net       tcp   smtp

       Example 2:
           Forward all ssh and http connection requests from the internet to
           local system 192.168.1.3

                       #ACTION SOURCE  DEST            PROTO   DEST    SOURCE  ORIGINAL
                       #                                       PORT    PORT(S) DEST
                       DNAT    net     loc:192.168.1.3 tcp     ssh,http

       Example 3:
           Forward all http connection requests from the internet to local
           system 192.168.1.3 with a limit of 3 per second and a maximum burst
           of 10

                       #ACTION SOURCE DEST            PROTO  DEST  SOURCE  ORIGINAL RATE
                       #                                     PORT  PORT(S) DEST     LIMIT
                       DNAT    net    loc:192.168.1.3 tcp    http  -       -        3/sec:10

       Example 4:
           Redirect all locally-originating www connection requests to port
           3128 on the firewall (Squid running on the firewall system) except
           when the destination address is 192.168.2.2

                       #ACTION  SOURCE DEST      PROTO DEST    SOURCE  ORIGINAL
                       #                               PORT    PORT(S) DEST
                       REDIRECT loc    3128      tcp   www      -      !192.168.2.2

       Example 5:
           All http requests from the internet to address 130.252.100.69 are
           to be forwarded to 192.168.1.3

                       #ACTION  SOURCE DEST            PROTO   DEST    SOURCE  ORIGINAL
                       #                                       PORT    PORT(S) DEST
                       DNAT      net   loc:192.168.1.3 tcp     80      -       130.252.100.69

       Example 6:
           You want to accept SSH connections to your firewall only from
           internet IP addresses 130.252.100.69 and 130.252.100.70

                       #ACTION  SOURCE DEST            PROTO   DEST    SOURCE  ORIGINAL
                       #                                       PORT    PORT(S) DEST
                       ACCEPT   net:130.252.100.69,130.252.100.70 $FW \
                                                       tcp     22

       Example 7:
           You wish to accept connections from the internet to your firewall
           on port 2222 and you want to forward them to local system
           192.168.1.3, port 22

                       #ACTION  SOURCE DEST                PROTO   DEST    SOURCE  ORIGINAL
                       #                                           PORT    PORT(S) DEST
                       DNAT     net    loc:192.168.1.3:22  tcp     2222

       Example 8:
           You want to redirect connection requests to port 80 randomly to the
           port range 81-90.

                       #ACTION  SOURCE DEST                PROTO DEST    SOURCE  ORIGINAL
                       #                                   PORT  PORT(S) DEST
                       REDIRECT net    $FW::81-90:random   tcp   www

       Example 9:
           Shorewall does not impose as much structure on the Netfilter rules
           in the 'nat' table as it does on those in the filter table. As a
           consequence, when using Shorewall versions before 4.1.4, care must
           be exercised when using DNAT and REDIRECT rules with zones defined
           with wildcard interfaces (those ending with '+'. Here is an
           example:

           shorewall-zones[3](8):

                       #ZONE       TYPE    OPTIONS
                       fw          firewall
                       net         ipv4
                       dmz         ipv4
                       loc         ipv4

           shorewall-interfaces[8](8):

                       #ZONE       INTERFACE       BROADCAST      OPTIONS
                       net         ppp0
                       loc         eth1            detect
                       dmz         eth2            detect
                       -           ppp+                           # Addresses are assigned from 192.168.3.0/24

           shorewall-host[9](8):

                       #ZONE       HOST(S)              OPTIONS
                       loc         ppp+:192.168.3.0/24

           rules:

                       #ACTION     SOURCE          DEST       PROTO       DEST
                       #                                                  PORT(S)
                       REDIRECT    loc             3128       tcp         80

           Note that it would have been tempting to simply define the loc zone
           entirely in shorewall-interfaces(8):

                       #******************* INCORRECT *****************
                       #ZONE       INTERFACE       BROADCAST      OPTIONS
                       net         ppp0
                       loc         eth1            detect
                       loc         ppp+
                       dmz         eth2

           This would have made it impossible to run a internet-accessible web
           server in the DMZ because all traffic entering ppp+ interfaces
           would have been redirected to port 3128 on the firewall and there
           would have been no net->fw ACCEPT rule for that traffic.

FILES

       /etc/shorewall/rules

SEE ALSO

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

NOTES

        1. shorewall-policy
           http://www.shorewall.net/manpages/shorewall-policy.html

        2. shorewall.conf
           http://www.shorewall.net/manpages/shorewall.conf.html

        3. shorewall-zones
           http://www.shorewall.net/manpages/shorewall-zones.html

        4. shorewall-nesting
           http://www.shorewall.net/manpages/shorewall-nesting.html

        5. shorewall-actions
           http://www.shorewall.net/manpages/shorewall-actions.html

        6. shorewall-exclusion
           http://www.shorewall.net/manpages/shorewall-exclusion.html

        7. http://shorewall.net/PortKnocking.html
           http://www.shorewall.net/manpages/../PortKnocking.html

        8. shorewall-interfaces
           http://www.shorewall.net/manpages/shorewall-interfaces.html

        9. shorewall-host
           http://www.shorewall.net/manpages/shorewall-hosts.html

[FIXME: source]                   06/17/2010