SHOREWALL-FILES(5)

Configuration Files

SHOREWALL-FILES(5)

NAME¶

files - Shorewall Configuration Files

SYNOPSIS¶

/etc/shorewall[6]/*

DESCRIPTION¶

The following are the Shorewall[6] configuration files:

•/etc/shorewall/shorewall.conf and /etc/shorewall6/shorewall6.conf[1] - used to set global firewall parameters.

•/etc/shorewall[6]/params[2] - use this file to set shell variables that you will expand in other files. It is always processed by /bin/sh or by the shell specified through SHOREWALL_SHELL in /etc/shorewall/shorewall.conf.

•/etc/shorewall[6]/zones[3] - partition the firewall's view of the world into zones.

•/etc/shorewall[6]/policy[4] - establishes firewall high-level policy.

•/etc/shorewall[6]/initdone - An optional Perl script that will be invoked by the Shorewall rules compiler when the compiler has finished it's initialization.

•/etc/shorewall[6]/interfaces[5] - describes the interfaces on the firewall system.

•/etc/shorewall[6]/hosts[6] - allows defining zones in terms of individual hosts and subnetworks.

•/etc/shorewall[6]/masq[7] - directs the firewall where to use many-to-one (dynamic) Network Address Translation (a.k.a. Masquerading) and Source Network Address Translation (SNAT). Superseded by /etc/shorewall[6]/snat in Shorewall 5.0.14 and not supported in Shorewall 5.1.0 and later versions.

•/etc/shorewall[6]/mangle[8] - supersedes /etc/shorewall/tcrules in Shorewall 4.6.0. Contains rules for packet marking, TTL, TPROXY, etc.

•/etc/shorewall[6]/rules[9] - defines rules that are exceptions to the overall policies established in /etc/shorewall/policy.

•/etc/shorewall[6]/nat[10] - defines one-to-one NAT rules.

•/etc/shorewall6/proxyarp[11] - defines use of Proxy ARP.

•/etc/shorewall6/proxyndp[12] - defines use of Proxy NDP.

•/etc/shorewall[6]/routestopped - defines hosts accessible when Shorewall is stopped. Superseded in Shorewall 4.6.8 by /etc/shorewall/stoppedrules. Not supported in Shorewall 5.0.0 and later versions.

•/etc/shorewall[6]/tcrules[13]- The file has a rather unfortunate name because it is used to define marking of packets for later use by both traffic control/shaping and policy routing. This file is superseded by /etc/shorewall/mangle in Shorewall 4.6.0. Not supported in Shorewall 5.0.0 and later releases.

•/etc/shorewall[6]/tos[14] - defines rules for setting the TOS field in packet headers. Superseded in Shorewall 4.5.1 by the TOS target in /etc/shorewall/tcrules (which file has since been superseded by /etc/shorewall/mangle). Not supported in Shorewall 5.0.0 and later versions.

•/etc/shorewall[6]/tunnels[15] - defines tunnels (VPN) with end-points on the firewall system.

•/etc/shorewall[6]/blacklist[16] - Deprecated in favor of /etc/shorewall/blrules. Lists blacklisted IP/subnet/MAC addresses. Not supported in Shorewall 5.0.0 and later releases.

•/etc/shorewall[6]/blrules — Added in Shorewall 4.5.0. Define blacklisting and whitelisting. Supersedes /etc/shorewall/blacklist.

•/etc/shorewall[6]/init - shell commands that you wish to execute at the beginning of a “shorewall start”, "shorewall reload" or “shorewall restart”.

•/etc/shorewall[6]/start - shell commands that you wish to execute near the completion of a “shorewall start”, "shorewall reload" or “shorewall restart”

•/etc/shorewall[6]/started - shell commands that you wish to execute after the completion of a “shorewall start”, "shorewall reload" or “shorewall restart”

•/etc/shorewall[6]/stop- commands that you wish to execute at the beginning of a “shorewall stop”.

•/etc/shorewall[6]/stopped - shell commands that you wish to execute at the completion of a “shorewall stop”.

•/etc/shorewall/ecn[17] - disable Explicit Congestion Notification (ECN - RFC 3168) to remote hosts or networks. Superseded by ECN entries in /etc/shorewall/mangle in Shorewall 5.0.6.

•/etc/shorewall/accounting[18] - define IP traffic accounting rules

•/etc/shorewall[6]/actions[19] and /usr/share/shorewall[6]/action.template allow user-defined actions.

•/etc/shorewall[6]/providers[20] - defines alternate routing tables.

•/etc/shorewall[6]/rtrules[21] - Defines routing rules to be used in conjunction with the routing tables defined in /etc/shorewall/providers.

•/etc/shorewall[6]/tcdevices[22], /etc/shorewall[6]/tcclasses[23], /etc/shorewall[6]/tcfilters[24] - Define complex traffic shaping.

•/etc/shorewall[6]/tcrules[13] - Mark or classify traffic for traffic shaping or multiple providers. Deprecated in Shorewall 4.6.0 in favor of /etc/shorewall/mangle. Not supported in Shorewall 5.0.0 and later releases.

•/etc/shorewall[6]/tcinterfaces[25] and /etc/shorewall[6]/tcpri[26] - Define simple traffic shaping.

•/etc/shorewall[6]/secmarks[27] - Added in Shorewall 4.4.13. Attach an SELinux context to selected packets.

•/etc/shorewall[6]/vardir[28] - Determines the directory where Shorewall maintains its state.

•/etc/shorewall/arprules[29] — Added in Shorewall 4.5.12. Allows specification of arptables rules.

•/etc/shorewall/mangle[8] -- Added in Shorewall 4.6.0. Supersedes/etc/shorewall/tcrules.

•/etc/shorewall[6]/snat[30] - directs the firewall where to use many-to-one (dynamic) Network Address Translation (a.k.a. Masquerading) and Source Network Address Translation (SNAT). Superseded /etc/shorewall[6]/masq in Shorewall 5.0.14

•/usr/share/shorewall[6]/actions.std - Actions defined by Shorewall.

•/usr/share/shorewall[6]/action.* - Details of actions defined by Shorewall.

•/usr/share/shorewall[6]/macro.* - Details of macros defined by Shorewall.

•/usr/share/shorewall[6]/modules — Specifies the kernel modules to be loaded during shorewall start/restart.

•/usr/share/shorewall[6]/helpers — Added in Shorewall 4.4.7. Specifies the kernel modules to be loaded during shorewall start/restart when LOAD_HELPERS_ONLY=Yes in shorewall.conf.

CONFIG_PATH¶

The CONFIG_PATH option in shorewall[6].conf(5)[20] determines where the compiler searches for configuration files. The default setting is CONFIG_PATH=/etc/shorewall:/usr/share/shorewall which means that the compiler first looks in /etc/shorewall and if it doesn't find the file, it then looks in /usr/share/shorewall.

You can change this setting to have the compiler look in different places. For example, if you want to put your own versions of standard macros in /etc/shorewall/Macros, then you could set CONFIG_PATH=/etc/shorewall:/etc/shorewall/Macros:/usr/share/shorewall and the compiler will use your versions rather than the standard ones.

COMMENTS¶

You may place comments in configuration files by making the first non-whitespace character a pound sign (“#”). You may also place comments at the end of any line, again by delimiting the comment from the rest of the line with a pound sign.

Example 1. Comments in a Configuration File

# This is a comment
ACCEPT  net     $FW      tcp     www     #This is an end-of-line comment

Important

Except in shorewall.conf(5)[1] and params(5)[2], if a comment ends with a backslash ("\"), the next line will also be treated as a comment. See Line Continuation below.

BLANK LINES¶

Most of the configuration files are organized into space-separated columns. If you don't want to supply a value in a column but want to supply a value in a following column, simply enter '-' to make the column appear empty.

Example:

#INTERFACE         BROADCAST            OPTIONS
br0                -                    routeback

LINE CONTINUATION¶

Lines may be continued using the usual backslash (“\”) followed immediately by a new line character (Enter key).

ACCEPT  net     $FW      tcp \↵
smtp,www,pop3,imap  #Services running on the firewall

Important

What follows does NOT apply to shorewall-params(5)[31] and shorewall.conf(5)[1].

In certain cases, leading white space is ignored in continuation lines:

1.The continued line ends with a colon (":")

2.The continued line ends with a comma (",")

Example (/etc/shorewall/rules):

#ACTION     SOURCE          DEST            PROTO           DPORT
ACCEPT      net:\


            206.124.146.177,\


            206.124.146.178,\


            206.124.146.180\


                            dmz             tcp             873

The leading white space on the first through third continuation lines is ignored so the SOURCE column effectively contains "net:206.124.146.177,206.124.147.178,206.124.146.180". Because the third continuation line does not end with a comma or colon, the leading white space in the last line is not ignored.

Important

A trailing backslash is not ignored in a comment. So the continued rule above can be commented out with a single '#' as follows:

#ACTION     SOURCE          DEST            PROTO           DPORT
#ACCEPT     net:\


            206.124.146.177,\


            206.124.146.178,\


            206.124.146.180\


                            dmz             tcp             873

ALTERNATIVE SPECIFICATION OF COLUMN VALUES¶

Some of the configuration files now have a large number of columns. That makes it awkward to specify a value for one of the right-most columns as you must have the correct number of intervening '-' columns.

This problem is addressed by allowing column values to be specified as column-name/value pairs.

There is considerable flexibility in how you specify the pairs:

•At any point, you can enter a left curly bracket ('{') followed by one or more specifications of the following forms:

column-name=value

column-name=>value

column-name:value

The pairs must be followed by a right curly bracket ("}").

The value may optionally be enclosed in double quotes.

The pairs must be separated by white space, but you can add a comma adjacent to the values for readability as in:

{ proto=>udp, port=1024
}

•You can also separate the pairs from columns by using a semicolon:

; proto:udp,
port:1024

In Shorewall 5.0.3, the sample configuration files and the man pages were updated to use the same column names in both the column headings and in the alternate specification format. The following table shows the column names for each of the table-oriented configuration files.

Note

Column names are case-insensitive.

File	Column names
accounting	action,chain, source, dest, proto, dport, sport, user, mark, ipsec, headers
conntrack	action,source,dest,proto,dport,sport,user,switch
blacklist	networks,proto,port,options
blrules	action,source,dest,proto,dport,sport,origdest,rate,user,mark,connlimit,time,headers,switch,helper
ecn	interface,hosts. Beginning with Shorewall 4.5.4, 'host' is a synonym for 'hosts'.
hosts	zone,hosts,options. Beginning with Shorewall 4.5.4, 'host' is a synonym for 'hosts'.
interfaces	zone,interface,broadcast,options
maclist	disposition,interface,mac,addresses
mangle	action,source,dest,proto,dport,sport,user,test,length,tos,connbytes,helper,headers
masq	interface,source,address,proto,port,ipsec,mark,user,switch
nat	external,interface,internal,allints,local
netmap	type,net1,interface,net2,net3,proto,dport,sport
notrack	source,dest,proto,dport,sport,user
policy	source,dest,policy,loglevel,limit,connlimit
providers	table,number,mark,duplicate,interface,gateway,options,copy
proxyarp and proxyndp	address,interface,external,haveroute,persistent
rtrules	source,dest,provider,priority
routes	provider,dest,gateway,device
routestopped	interface,hosts,options,proto,dport,sport
rules	action,source,dest,proto,dport,sport,origdest,rate,user,mark,connlimit,time,headers,switch,helper
secmarks	secmark,chain,source,dest,proto,dport,sport,user,mark
tcclasses	interface,mark,rate,ceil,prio,options
tcdevices	interface,in_bandwidth,out_bandwidth,options,redirect
tcfilters	class,source,dest,proto,dport,sport,tos,length
tcinterfaces	interface,type,in_bandwidth,out_bandwidth
tcpri	band,proto,port,address,interface,helper
tcrules	mark,source,dest,proto,dport,sport,user,test,length,tos,connbytes,helper,headers. Beginning with Shorewall 4.5.3, 'action' is a synonym for 'mark'.
tos	source,dest,proto,dport,sport,tos,mark
tunnels	type,zone,gateway,gateway_zone. Beginning with Shorewall 4.5.3, 'gateways' is a synonym for 'gateway'. Beginning with Shorewall 4.5.4, 'gateway_zones' is a synonym for 'gateway_zone'.
zones	zone,type,options,in_options,out_options

Example (rules file):

#ACTION         SOURCE            DEST            PROTO   DPORT
DNAT            net               loc:10.0.0.1    tcp     80    ; mark="88"

Here's the same line in several equivalent formats:

{ action=>DNAT, source=>net, dest=>loc:10.0.0.1, proto=>tcp, dport=>80, mark=>88 }
; action:"DNAT" source:"net"  dest:"loc:10.0.0.1" proto:"tcp" dport:"80" mark:"88"
DNAT { source=net dest=loc:10.0.0.1 proto=tcp dport=80 mark=88 }

Beginning with Shorewall 5.0.11, ip[6]table comments can be attached to individual rules using the comment keyword.

Example from the rules file:



        ACCEPT net $FW { proto=tcp, dport=22, comment="Accept \"SSH\"" }

As shown in that example, when the comment contains whitespace, it must be enclosed in double quotes and any embedded double quotes must be escaped using a backslash ("\").

TIME COLUMNS¶

Several of the files include a TIME column that allows you to specify times when the rule is to be applied. Contents of this column is a list of timeelements separated by apersands (&).

Each timeelement is one of the following:

timestart=hh:mm[:ss]

Defines the starting time of day.

timestop=hh:mm[:ss]

Defines the ending time of day.

contiguous

Added in Shoreawll 5.0.12. When timestop is smaller than timestart value, match this as a single time period instead of distinct intervals. See the Examples below.

utc

Times are expressed in Greenwich Mean Time.

localtz

Deprecated by the Netfilter team in favor of kerneltz. Times are expressed in Local Civil Time (default).

kerneltz

Added in Shorewall 4.5.2. Times are expressed in Local Kernel Time (requires iptables 1.4.12 or later).

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:

To match on weekends, use:

weekdays=Sat,Sun

Or, to match (once) on a national holiday block:

datestart=2016-12-24&datestop=2016-12-27

Since the stop time is actually inclusive, you would need the following stop time to not match the first second of the new day:

datestart=2016-12-24T17:00&datestop=2016-12-27T23:59:59

During Lunch Hour

The fourth Friday in the month:

weekdays=Fri&monthdays=22,23,24,25,26,27,28

Matching across days might not do what is expected. For instance,

weekdays=Mon&timestart=23:00&timestop=01:00

Will match Monday, for one hour from midnight to 1 a.m., and then again for another hour from 23:00 onwards. If this is unwanted, e.g. if you would like 'match for two hours from Montay 23:00 onwards' you need to also specify the contiguous option in the example above.

SWITCHES¶

here are times when you would like to enable or disable one or more rules in the configuration without having to do a shorewall reload or shorewall restart. This may be accomplished using the SWITCH column in shorewall-rules[32] (5) or shorewall6-rules[32] (5). Using this column requires that your kernel and iptables include Condition Match Support and you must be running Shorewall 4.4.24 or later. See the output of shorewall show capabilities and shorewall version to determine if you can use this feature.

The SWITCH column contains the name of a switch. Each switch is initially in the off position. You can turn on the switch named switch1 by:

echo 1 >
/proc/net/nf_condition/switch1

You can turn it off again by:

echo 0 >
/proc/net/nf_condition/switch1

If you simply include the switch name in the SWITCH column, then the rule is enabled only when the switch is on. If you precede the switch name with ! (e.g., !switch1), then the rule is enabled only when the switch is off. Switch settings are retained over shorewall reload.

Shorewall requires that switch names:

•begin with a letter and be composed of letters, digits, underscore ('_') or hyphen ('-'); and

•be 30 characters or less in length.

Multiple rules can be controlled by the same switch.

Example:

Forward port 80 to dmz host $BACKUP if switch 'primary_down' is on.

#ACTION     SOURCE          DEST        PROTO       DPORT        SPORT     ORIGDEST   RATE      USER      MARK    CONNLIMIT     TIME     HEADERS    SWITCH
DNAT        net             dmz:$BACKUP tcp         80           -         -          -         -         -       -             -        -          primary_down