Ubuntu Manpage: zones - Shorewall zone declaration file

NAME

       zones - Shorewall zone declaration file

SYNOPSIS

       /etc/shorewall/zones

DESCRIPTION

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.

Example:

#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.

TYPE

ip
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.

ipsec
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.

firewall
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.

bport
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.

vserver
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.

loopback
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.

local
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) - [option[,option]...]
A comma-separated list of options. With the exception of the mss and blacklist options, these only
apply to TYPE ipsec zones.

dynamic_shared
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.

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

spi=<number>
where number is the SPI of the SA used to encrypt/decrypt packets.

proto=ah|esp|ipcomp
IPSEC Encapsulation Protocol

mss=number
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.

mode=transport|tunnel
IPSEC mode

tunnel-src=address[/mask]
only available with mode=tunnel

tunnel-dst=address[/mask]
only available with mode=tunnel

strict
Means that packets must match all rules.

next
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 "-".

FILES

       /etc/shorewall/zones

       /etc/shorewall6/zones

NOTES

        1. shorewall.conf
           https://shorewall.org/manpages/shorewall.conf.html

        2. shorewall-nesting
           https://shorewall.org/manpages/shorewall-nesting.html

        3. shorewall-hosts
           https://shorewall.org/manpages/shorewall-hosts.html

        4. https://shorewall.org/Multiple_Zones.html
           https://shorewall.org/Multiple_Zones.html

        5. https://shorewall.org/configuration_file_basics.htm#Pairs
           https://shorewall.org/configuration_file_basics.htm#Pairs

NAME

SYNOPSIS

DESCRIPTION

FILES

SEE ALSO

NOTES