Provided by: shorewall_5.2.3.4-1_all bug


       zones - Shorewall zone declaration file




       The /etc/shorewall/zones file declares your network zones. You specify the hosts in each
       zone through entries in /etc/shorewall/interfaces or /etc/shorewall/hosts.

       The columns in the file are as follows (where the column name is followed by a different
       name in parentheses, the different name is used in the alternate specification syntax).

       ZONE - zone[:parent-zone[,parent-zone]...]
           Name of the zone. Must start with a letter and consist of letters, digits or '_'. The
           names "all", "none", "any", "SOURCE" and "DEST" are reserved and may not be used as
           zone names. The maximum length of a zone name is determined by the setting of the
           LOGFORMAT option in shorewall.conf[1](5). With the default LOGFORMAT, zone names can
           be at most 5 characters long.  The maximum length of an iptables log prefix is 29
           bytes. As explained in shorewall.conf[1] (5), the legacy default LOGPREFIX formatting
           string is “Shorewall:%s:%s:” where the first %s is replaced by the chain name and the
           second is replaced by the disposition.

           •   The "Shorewall:%s:%s:" formatting string has 12 fixed characters ("Shorewall" and
               three colons).

           •   The longest of the standard dispositions are ACCEPT and REJECT which have 6
               characters each.

           •   The canonical name for the chain containing the rules for traffic going from zone
               1 to zone 2 is "<zone 1>2<zone 2>" or "<zone 1>-<zone 2>".

           •   So if M is the maximum zone name length, such chains can have length 2*M + 1.
                   12 + 6 + 2*M + 1 = 29 which reduces to
                   2*M = 29 - 12 - 6 - 1 = 10 or
                   M = 5

           In Shorewall 5.1.0, the LOGFORMAT in the default and sample shorewall.conf files was
           changed to "%s:%s ".

           •   That formatting string has 2 fixed characters (":" and a space).

           •   So the maximum zone name length M is calculated as:
                   2 + 6 + 2*M + 1 = 29
                   2M = 29 - 2 - 6 - 1 = 20
                   M = 10
           The order in which Shorewall matches addresses from packets to zones is determined by
           the order of zone declarations. Where a zone is nested in one or more other zones, you
           may either ensure that the nested zone precedes its parents in this file, or you may
           follow the (sub)zone name by ":" and a comma-separated list of the parent zones. The
           parent zones must have been declared in earlier records in this file. See
           shorewall-nesting[2](5) for additional information.


               #ZONE     TYPE     OPTIONS         IN OPTIONS        OUT OPTIONS
               a         ip
               b         ip
               c:a,b     ip

           Currently, Shorewall uses this information to reorder the zone list so that parent
           zones appear after their subzones in the list. The IMPLICIT_CONTINUE option in
           shorewall.conf[1](5) can also create implicit CONTINUE policies to/from the subzone.

           Where an ipsec zone is explicitly included as a child of an ip zone, the ruleset
           allows CONTINUE policies (explicit or implicit) to work as expected.

           In the future, Shorewall may make additional use of nesting information.


               This is the standard Shorewall zone type and is the default if you leave this
               column empty or if you enter "-" in the column. Communication with some zone hosts
               may be encrypted. Encrypted hosts are designated using the 'ipsec' option in
               shorewall-hosts[3](5). For clarity, this zone type may be specified as ipv4 in
               IPv4 configurations and ipv6 in IPv6 configurations.

               Communication with all zone hosts is encrypted. Your kernel and iptables must
               include policy match support. For clarity, this zone type may be specified as
               ipsec4 in IPv4 configurations and ipsec6 in IPv6 configurations.

               Designates the firewall itself. You must have exactly one 'firewall' zone. No
               options are permitted with a 'firewall' zone. The name that you enter in the ZONE
               column will be stored in the shell variable $FW which you may use in other
               configuration files to designate the firewall zone.

               The zone is associated with one or more ports on a single bridge. For clarity,
               this zone type may be specified as bport4 in IPv4 configurations and bport6 in
               IPv6 configurations.

               Added in Shorewall 4.4.11 Beta 2 - A zone composed of Linux-vserver guests. The
               zone contents must be defined in shorewall-hosts[3] (5).

               Vserver zones are implicitly handled as subzones of the firewall zone.

               Added in Shorewall 4.5.17.

               Normally, Shorewall treats the loopback interface (lo) in the following way:

               •   By default, all traffic through the interface is ACCEPTed.

               •   If a $FW -> $FW policy is defined or $FW -> $FW rules are defined, they are
                   placed in a chain named ${FW}2${F2} or ${FW}-${FW} (e.g., 'fw2fw' or 'fw-fw' )
                   depending on the ZONE2ZONE setting in shorewall.conf[1](5).

               •   $FW -> $FW traffic is only filtered in the OUTPUT chain.

               By defining a loopback zone and associating it with the loopback interface in
               shorewall-interfaces(5), you can effect a slightly different model. Suppose that
               the loopback zone name is 'local'; then:

               •   Both $FW -> local and local -> $FW chains are created.

               •   The $FW -> local and local -> $FW policies may be different.

               •   Both $FW -> local and local -> $FW rules may be specified.

               Rules to/from the loopback zone and any zone other than the firewall zone are
               ignored with a warning.

               loopback zones may be nested within other loopback zones.

               Added in Shorewall 4.5.17.  local is the same as ipv4 with the exception that the
               zone is only accessible from the firewall and vserver zones.

       OPTIONS, IN OPTIONS and OUT OPTIONS (options, in_options, out_options) -
           A comma-separated list of options. With the exception of the mss and blacklist
           options, these only apply to TYPE ipsec zones.

               Added in Shorewall 4.5.9. May only be specified in the OPTIONS column and
               indicates that only a single ipset should be created for this zone if it has
               multiple dynamic entries in shorewall-hosts[3](5). Without this option, a separate
               ipset is created for each interface.

               where number is specified using setkey(8) using the 'unique:number option for the
               SPD level.

               where number is the SPI of the SA used to encrypt/decrypt packets.

               IPSEC Encapsulation Protocol

               sets the MSS field in TCP packets. If you supply this option, you should also set
               FASTACCEPT=No in shorewall.conf[1](5) to insure that both the SYN and SYN,ACK
               packets have their MSS field adjusted.

               IPSEC mode

               only available with mode=tunnel

               only available with mode=tunnel

               Means that packets must match all rules.

               Separates rules; can only be used with strict

           The options in the OPTIONS column are applied to both incoming and outgoing traffic.
           The IN OPTIONS are applied to incoming traffic (in addition to OPTIONS) and the OUT
           OPTIONS are applied to outgoing traffic.

           If you wish to leave a column empty but need to make an entry in a following column,
           use "-".




SEE ALSO[4].[5]



        1. shorewall.conf

        2. shorewall-nesting

        3. shorewall-hosts