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