Provided by: shorewall_5.2.3.2-1_all bug

NAME

       interfaces - Shorewall interfaces file

SYNOPSIS

       /etc/shorewall[6]/interfaces

DESCRIPTION

       The interfaces file serves to define the firewall's network interfaces to Shorewall. The
       order of entries in this file is not significant in determining zone composition.

       Beginning with Shorewall 4.5.3, the interfaces file supports two different formats:

       FORMAT 1 (default - deprecated)
           There is a BROADCAST column which can be used to specify the broadcast address
           associated with the interface.

       FORMAT 2
           The BROADCAST column is omitted.

       The format is specified by a line as follows:

       ?FORMAT {1|2}

       The columns in the file are as follows.

       ZONE - zone-name
           Zone for this interface. Must match the name of a zone declared in
           /etc/shorewall/zones. You may not list the firewall zone in this column.

           If the interface serves multiple zones that will be defined in the
           shorewall-hosts[1](5) file, you should place "-" in this column.

           If there are multiple interfaces to the same zone, you must list them in separate
           entries.

           Example:

               #ZONE   INTERFACE       BROADCAST
               loc     eth1            -
               loc     eth2            -

       INTERFACE - interface[:port]
           Logical name of interface. Each interface may be listed only once in this file. You
           may NOT specify the name of a "virtual" interface (e.g., eth0:0) here; see
           http://www.shorewall.net/FAQ.htm#faq18[2]. If the physical option is not specified,
           then the logical name is also the name of the actual interface.

           You may use wildcards here by specifying a prefix followed by the plus sign ("+"). For
           example, if you want to make an entry that applies to all PPP interfaces, use 'ppp+';
           that would match ppp0, ppp1, ppp2, ...

           When using Shorewall versions before 4.1.4, care must be exercised when using
           wildcards where there is another zone that uses a matching specific interface. See
           shorewall-nesting[3](5) for a discussion of this problem.

           Shorewall allows '+' as an interface name, but that usage is deprecated. A better
           approach is to specify 'physical=+' in the OPTIONS column (see below).

           There is no need to define the loopback interface (lo) in this file.

           If a port is given, then the interface must have been defined previously with the
           bridge option. The OPTIONS column may not contain the following options when a port is
           given.
               arp_filter
               arp_ignore
               bridge
               log_martians
               mss
               optional
               proxyarp
               required
               routefilter
               sourceroute
               upnp
               wait
           Beginning with Shorewall 4.5.17, if you specify a zone for the 'lo' interface, then
           that zone must be defined as type local in shorewall6-zones[4](5).

       BROADCAST (Optional) - {-|detect|address[,address]...}
           Only available if FORMAT 1.

           If you use the special value detect, Shorewall will detect the broadcast address(es)
           for you if your iptables and kernel include Address Type Match support.

           If your iptables and/or kernel lack Address Type Match support then you may list the
           broadcast address(es) for the network(s) to which the interface belongs. For P-T-P
           interfaces, this column is left blank. If the interface has multiple addresses on
           multiple subnets then list the broadcast addresses as a comma-separated list.

           If you don't want to give a value for this column but you want to enter a value in the
           OPTIONS column, enter - in this column.

       OPTIONS (Optional) - [option[,option]...]
           A comma-separated list of options from the following list. The order in which you list
           the options is not significant but the list should have no embedded white-space.

           accept_ra[={0|1|2}]
               IPv6 only; added in Shorewall 4.5.16. Values are:

               0
                   Do not accept Router Advertisements.

               1
                   Accept Route Advertisements if forwarding is disabled.

               2
                   Overrule forwarding behavior. Accept Route Advertisements even if forwarding
                   is enabled.

               If the option is specified without a value, then the value 1 is assumed.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.

           arp_filter[={0|1}]
               IPv4 only. If specified, this interface will only respond to ARP who-has requests
               for IP addresses configured on the interface. If not specified, the interface can
               respond to ARP who-has requests for IP addresses on any of the firewall's
               interface. The interface must be up when Shorewall is started.

               Only those interfaces with the arp_filter option will have their setting changed;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.

           arp_ignore[=number]
               IPv4 only. If specified, this interface will respond to arp requests based on the
               value of number (defaults to 1).

               1 - reply only if the target IP address is local address configured on the
               incoming interface

               2 - reply only if the target IP address is local address configured on the
               incoming interface and the sender's IP address is part from same subnet on this
               interface's address

               3 - do not reply for local addresses configured with scope host, only resolutions
               for global and link

               4-7 - reserved

               8 - do not reply for all local addresses

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.

                   Warning
                   Do not specify arp_ignore for any interface involved in Proxy ARP[5].

           blacklist
               Checks packets arriving on this interface against the shorewall-blacklist[6](5)
               file.

               Beginning with Shorewall 4.4.13:

               ·   If a zone is given in the ZONES column, then the behavior is as if blacklist
                   had been specified in the IN_OPTIONS column of shorewall-zones[7](5).

               ·   Otherwise, the option is ignored with a warning: WARNING: The 'blacklist'
                   option is ignored on multi-zone interfaces

           bridge
               Designates the interface as a bridge. Beginning with Shorewall 4.4.7, setting this
               option also sets routeback.

                   Note
                   If you have a bridge that you don't intend to define bport zones on, then it
                   is best to omit this option and simply specify routeback.

           dbl={none|src|dst|src-dst}
               Added in Shorewall 5.0.10. This option defined whether or not dynamic blacklisting
               is applied to packets entering the firewall through this interface and whether the
               source address and/or destination address is to be compared against the
               ipset-based dynamic blacklist (DYNAMIC_BLACKLIST=ipset... in
               shorewall.conf(5)[8]). The default is determine by the setting of
               DYNAMIC_BLACKLIST:

               DYNAMIC_BLACKLIST=No
                   Default is none (e.g., no dynamic blacklist checking).

               DYNAMIC_BLACKLIST=Yes
                   Default is src (e.g., the source IP address is checked).

               DYNAMIC_BLACKLIST=ipset[-only]
                   Default is src.

               DYNAMIC_BLACKLIST=ipset[-only],src-dst...
                   Default is src-dst (e.g., the source IP addresses in checked against the ipset
                   on input and the destination IP address is checked against the ipset on
                   packets originating from the firewall and leaving through this interface).

               The normal setting for this option will be dst or none for internal interfaces and
               src or src-dst for Internet-facing interfaces.

           destonly
               Added in Shorewall 4.5.17. Causes the compiler to omit rules to handle traffic
               from this interface.

           dhcp
               Specify this option when any of the following are true:

                1. the interface gets its IP address via DHCP

                2. the interface is used by a DHCP server running on the firewall

                3. the interface has a static IP but is on a LAN segment with lots of DHCP
                   clients.

                4. the interface is a simple bridge[9] with a DHCP server on one port and DHCP
                   clients on another port.

                       Note
                       If you use Shorewall-perl for firewall/bridging[10], then you need to
                       include DHCP-specific rules in shorewall-rules[11](5). DHCP uses UDP ports
                       67 and 68.

               This option allows DHCP datagrams to enter and leave the interface.

           forward[={0|1}]
               IPv6 only Sets the /proc/sys/net/ipv6/conf/interface/forwarding option to the
               specified value. If no value is supplied, then 1 is assumed.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.

           ignore[=1]
               When specified, causes the generated script to ignore up/down events from
               Shorewall-init for this device. Additionally, the option exempts the interface
               from hairpin filtering. When '=1' is omitted, the ZONE column must contain '-' and
               ignore must be the only OPTION.

               Beginning with Shorewall 4.5.5, may be specified as 'ignore=1' which only causes
               the generated script to ignore up/down events from Shorewall-init; hairpin
               filtering is still applied. In this case, the above restrictions on the ZONE and
               OPTIONS columns are lifted.

           loopback
               Added in Shorewall 4.6.6. Designates the interface as the loopback interface. This
               option is assumed if the interface's physical name is 'lo'. Only one interface man
               have the loopback option specified.

           logmartians[={0|1}]
               IPv4 only. Turn on kernel martian logging (logging of packets with impossible
               source addresses. It is strongly suggested that if you set routefilter on an
               interface that you also set logmartians. Even if you do not specify the
               routefilter option, it is a good idea to specify logmartians because your
               distribution may have enabled route filtering without you knowing it.

               Only those interfaces with the logmartians option will have their setting changed;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

               To find out if route filtering is set on a given interface, check the contents of
               /proc/sys/net/ipv4/conf/interface/rp_filter - a non-zero value indicates that
               route filtering is enabled.

               Example:

                           teastep@lists:~$ cat /proc/sys/net/ipv4/conf/eth0/rp_filter
                           1
                           teastep@lists:~$

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.
               This option may also be enabled globally in the shorewall.conf[8](5) file.

           maclist
               Connection requests from this interface are compared against the contents of
               shorewall-maclist[12](5). If this option is specified, the interface must be an
               Ethernet NIC and must be up before Shorewall is started.

           mss=number
               Added in Shorewall 4.0.3. Causes forwarded TCP SYN packets entering or leaving on
               this interface to have their MSS field set to the specified number.

           nets=(net[,...])
               Limit the zone named in the ZONE column to only the listed networks. The
               parentheses may be omitted if only a single net is given (e.g.,
               nets=192.168.1.0/24). Limited broadcast to the zone is supported. Beginning with
               Shorewall 4.4.1, multicast traffic to the zone is also supported.

           nets=dynamic
               Defines the zone as dynamic. Requires ipset match support in your iptables and
               kernel. See http://www.shorewall.net/Dynamic.html[13] for further information.

           nodbl
               Added in Shorewall 5.0.8. When specified, dynamic blacklisting is disabled on the
               interface. Beginning with Shorewall 5.0.10, nodbl is equivalent to dbl=none.

           nosmurfs
               IPv4 only. Filter packets for smurfs (packets with a broadcast address as the
               source).

               Smurfs will be optionally logged based on the setting of SMURF_LOG_LEVEL in
               shorewall.conf[8](5). After logging, the packets are dropped.

           optional
               When optional is specified for an interface, Shorewall will be silent when:

               ·   a /proc/sys/net/ipv[46]/conf/ entry for the interface cannot be modified
                   (including for proxy ARP or proxy NDP).

               ·   The first address of the interface cannot be obtained.

               May not be specified with required.

           physical=name
               Added in Shorewall 4.4.4. When specified, the interface or port name in the
               INTERFACE column is a logical name that refers to the name given in this option.
               It is useful when you want to specify the same wildcard port name on two or more
               bridges. See http://www.shorewall.net/bridge-Shorewall-perl.html#Multiple[14].

               If the interface name is a wildcard name (ends with '+'), then the physical name
               must also end in '+'. The physical name may end in '+' (or be exactly '+') when
               the interface name is not a wildcard name.

               If physical is not specified, then it's value defaults to the interface name.

           proxyarp[={0|1}]
               IPv4 only. Sets /proc/sys/net/ipv4/conf/interface/proxy_arp. Do NOT use this
               option if you are employing Proxy ARP through entries in
               shorewall-proxyarp[15](5). This option is intended solely for use with Proxy ARP
               sub-networking as described at:
               http://tldp.org/HOWTO/Proxy-ARP-Subnet/index.html.[16]

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.
               Only those interfaces with the proxyarp option will have their setting changed;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

           proxyndp[={0|1}]
               IPv6 only. Sets /proc/sys/net/ipv6/conf/interface/proxy_ndp.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.
               Only those interfaces with the proxyndp option will have their setting changed;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

           required
               Added in Shorewall 4.4.10. If this option is set, the firewall will fail to start
               if the interface is not usable. May not be specified together with optional.

           routeback[={0|1}]
               If specified, indicates that Shorewall should include rules that allow traffic
               arriving on this interface to be routed back out that same interface. This option
               is also required when you have used a wildcard in the INTERFACE column if you want
               to allow traffic between the interfaces that match the wildcard.

               Beginning with Shorewall 4.4.20, if you specify this option, then you should also
               specify either sfilter (see below) or routefilter on all interfaces (see below).

               Beginning with Shorewall 4.5.18, you may specify this option to explicitly reset
               (e.g., routeback=0). This can be used to override Shorewall's default setting for
               bridge devices which is routeback=1.

           routefilter[={0|1|2}]
               IPv4 only. Turn on kernel route filtering for this interface (anti-spoofing
               measure).

               Only those interfaces with the routefilter option will have their setting changes;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

               The value 2 is only available with Shorewall 4.4.5.1 and later when the kernel
               version is 2.6.31 or later. It specifies a loose form of reverse path filtering.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.
               This option can also be enabled globally via the ROUTE_FILTER option in the
               shorewall.conf[8](5) file.

                   Important
                   If ROUTE_FILTER=Yes in shorewall.conf[8](5), or if your distribution sets
                   net.ipv4.conf.all.rp_filter=1 in /etc/sysctl.conf, then setting routefilter=0
                   in an interface entry will not disable route filtering on that interface! The
                   effective setting for an interface is the maximum of the contents of
                   /proc/sys/net/ipv4/conf/all/rp_filter and the routefilter setting specified in
                   this file (/proc/sys/net/ipv4/conf/interface/rp_filter).

                   Note
                   There are certain cases where routefilter cannot be used on an interface:

                   ·   If USE_DEFAULT_RT=Yes in shorewall.conf[8](5) and the interface is listed
                       in shorewall-providers[17](5).

                   ·   If there is an entry for the interface in shorewall-providers[17](5) that
                       doesn't specify the balance option.

                   ·   If IPSEC is used to allow a road-warrior to have a local address, then any
                       interface through which the road-warrior might connect cannot specify
                       routefilter.
               Beginning with Shorewall 5.1.1, when routefilter is set to a non-zero value, the
               logmartians option is also implicitly set. If you actually want route filtering
               without logging, then you must also specify logmartians=0 after routefilter.

           rpfilter
               Added in Shorewall 4.5.7. This is an anti-spoofing measure that requires the
               'RPFilter Match' capability in your iptables and kernel. It provides a more
               efficient alternative to the sfilter option below. It performs a function similar
               to routefilter (see above) but works with Multi-ISP configurations that do not use
               balanced routes.

           sfilter=(net[,...])
               Added in Shorewall 4.4.20. This option provides an anti-spoofing alternative to
               routefilter on interfaces where that option cannot be used, but where the
               routeback option is required (on a bridge, for example). On these interfaces,
               sfilter should list those local networks that are connected to the firewall
               through other interfaces.

           sourceroute[={0|1}]
               If this option is not specified for an interface, then source-routed packets will
               not be accepted from that interface unless it has been explicitly enabled via
               sysconf. Only set this option to 1 (enable source routing) if you know what you
               are doing. This might represent a security risk and is usually unneeded.

               Only those interfaces with the sourceroute option will have their setting changed;
               the value assigned to the setting will be the value specified (if any) or 1 if no
               value is given.

                   Note
                   This option does not work with a wild-card physical name (e.g., eth0.+).
                   Beginning with Shorewall 5.1.10, If this option is specified, a warning is
                   issued and the option is ignored.

           tcpflags[={0|1}]
               Packets arriving on this interface are checked for certain illegal combinations of
               TCP flags. Packets found to have such a combination of flags are handled according
               to the setting of TCP_FLAGS_DISPOSITION after having been logged according to the
               setting of TCP_FLAGS_LOG_LEVEL.

               Beginning with Shorewall 4.6.0, tcpflags=1 is the default. To disable this option,
               specify tcpflags=0.

           unmanaged
               Added in Shorewall 4.5.18. Causes all traffic between the firewall and hosts on
               the interface to be accepted. When this option is given:

               ·   The ZONE column must contain '-'.

               ·   Only the following other options are allowed with unmanaged:
                       arp_filter
                       arp_ignore
                       ignore
                       routefilter
                       optional
                       physical
                       routefilter
                       proxyarp
                       proxyudp
                       sourceroute

           upnp
               Incoming requests from this interface may be remapped via UPNP (upnpd). See
               http://www.shorewall.net/UPnP.html[18]. Supported in IPv4 and in IPv6 in Shorewall
               5.1.4 and later.

           upnpclient
               This option is intended for laptop users who always run Shorewall on their system
               yet need to run UPnP-enabled client apps such as Transmission (BitTorrent client).
               The option causes Shorewall to detect the default gateway through the interface
               and to accept UDP packets from that gateway. Note that, like all aspects of UPnP,
               this is a security hole so use this option at your own risk. Supported in IPv4 and
               in IPv6 in Shorewall 5.1.4 and later.

           wait=seconds
               Added in Shorewall 4.4.10. Causes the generated script to wait up to seconds
               seconds for the interface to become usable before applying the required or
               optional options.

EXAMPLE

       IPv4 Example 1:
           Suppose you have eth0 connected to a DSL modem and eth1 connected to your local
           network and that your local subnet is 192.168.1.0/24. The interface gets its IP
           address via DHCP from subnet 206.191.149.192/27. You have a DMZ with subnet
           192.168.2.0/24 using eth2. Your iptables and/or kernel do not support "Address Type
           Match" and you prefer to specify broadcast addresses explicitly rather than having
           Shorewall detect them.

           Your entries for this setup would look like:

               ?FORMAT 1
               #ZONE   INTERFACE BROADCAST        OPTIONS
               net     eth0      206.191.149.223  dhcp
               loc     eth1      192.168.1.255
               dmz     eth2      192.168.2.255

       Example 2:
           The same configuration without specifying broadcast addresses is:

               ?FORMAT 2
               #ZONE   INTERFACE OPTIONS
               net     eth0      dhcp
               loc     eth1
               dmz     eth2

       Example 3:
           You have a simple dial-in system with no Ethernet connections.

               ?FORMAT 2
               #ZONE   INTERFACE OPTIONS
               net     ppp0      -

       Example 4 (Shorewall 4.4.9 and later):
           You have a bridge with no IP address and you want to allow traffic through the bridge.

               ?FORMAT 2
               #ZONE   INTERFACE OPTIONS
               -       br0       bridge

FILES

       /etc/shorewall/interfaces

       /etc/shorewall6/interfaces

SEE ALSO

       http://www.shorewall.net/configuration_file_basics.htm#Pairs[19]

       shorewall(8)

NOTES

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

        2. http://www.shorewall.net/FAQ.htm#faq18
           http://www.shorewall.net/FAQ.htm#faq18

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

        4. shorewall6-zones
           http://www.shorewall.net/manpages6/shorewall6-zones.html

        5. Proxy ARP
           http://www.shorewall.net/ProxyARP.htm

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

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

        8. shorewall.conf(5)
           http://www.shorewall.net/manpages/shorewall.conf.html

        9. simple bridge
           http://www.shorewall.net/SimpleBridge.html

       10. Shorewall-perl for firewall/bridging
           http://www.shorewall.net/bridge-Shorewall-perl.html

       11. shorewall-rules
           http://www.shorewall.net/manpages/shorewall-rules.html

       12. shorewall-maclist
           http://www.shorewall.net/manpages/shorewall-maclist.html

       13. http://www.shorewall.net/Dynamic.html
           http://www.shorewall.net/Dynamic.html

       14. http://www.shorewall.net/bridge-Shorewall-perl.html#Multiple
           http://www.shorewall.net/bridge-Shorewall-perl.html#Multiple

       15. shorewall-proxyarp
           http://www.shorewall.net/manpages/shorewall-proxyarp.html

       16. http://tldp.org/HOWTO/Proxy-ARP-Subnet/index.html.
           http://tldp.org/HOWTO/Proxy-ARP-Subnet/index.html

       17. shorewall-providers
           http://www.shorewall.net/manpages/shorewall-providers.html

       18. http://www.shorewall.net/UPnP.html
           http://www.shorewall.net/UPnP.html

       19. http://www.shorewall.net/configuration_file_basics.htm#Pairs
           http://www.shorewall.net/configuration_file_basics.htm#Pairs