NAME

DESCRIPTION

STATEMENT ORDER

-Macros

User-defined variables may be defined and used later, simplifying the configuration file. Macros must be defined before they are referenced in pf.conf.

-Tables

Tables provide a mechanism for increasing the performance and flexibility of rules with large numbers of source or destination addresses.

-Options

Options tune the behaviour of the packet filtering engine.

-TrafficNormalization (e.g. scrub)

Traffic normalization protects internal machines against inconsistencies in Internet protocols and implementations.

-Queueing

Queueing provides rule-based bandwidth control.

-Translation(Various forms of NAT)

Translation rules specify how addresses are to be mapped or redirected to other addresses.

-PacketFiltering

Packet filtering provides rule-based blocking or passing of packets.

include "/etc/pf/sub.filter.conf"

MACROS

ext_if = \&"kue0\&"
all_ifs = \&"{\&" $ext_if lo0 \&"}\&"
pass out on $ext_if from any to any
pass in  on $ext_if proto tcp from any to any port 25

TABLES

manually

Persistent tables can be manually created with the add or replace option of pfctl(8), before or after the ruleset has been loaded.

pf.conf

Table definitions can be placed directly in this file, and loaded at the same time as other rules are loaded, atomically. Table definitions inside pf.conf use the table statement, and are especially useful to define non-persistent tables. The contents of a pre-existing table defined without a list of addresses to initialize it is not altered when pf.conf is loaded. A table initialized with the empty list, { }, will be cleared on load.

persist

The persist flag forces the kernel to keep the table even when no rules refer to it. If the flag is not set, the kernel will automatically remove the table when the last rule referring to it is flushed.

const

The const flag prevents the user from altering the contents of the table once it has been created. Without that flag, pfctl(8) can be used to add or remove addresses from the table at any time, even when running with securelevel(7) = 2.

counters

The counters flag enables per-address packet and byte counters which can be displayed with pfctl(8).

table \*(Ltprivate\*(Gt const { 10/8, 172.16/12, 192.168/16 }
table \*(Ltbadhosts\*(Gt persist
block on fxp0 from { \*(Ltprivate\*(Gt, \*(Ltbadhosts\*(Gt } to any

# pfctl -t badhosts -Tadd 204.92.77.111

table \*(Ltspam\*(Gt persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&"
block on fxp0 from \*(Ltspam\*(Gt to any

OPTIONS

settimeout

interval

Interval between purging expired states and fragments.

frag

Seconds before an unassembled fragment is expired.

src.track

Length of time to retain a source tracking entry after the last state expires.

When a packet matches a stateful connection, the seconds to live for the connection will be updated to that of the proto.modifier which corresponds to the connection state. Each packet which matches this state will reset the TTL. Tuning these values may improve the performance of the firewall at the risk of dropping valid idle connections.

tcp.first

The state after the first packet.

tcp.opening

The state before the destination host ever sends a packet.

tcp.established

The fully established state.

tcp.closing

The state after the first FIN has been sent.

tcp.finwait

The state after both FINs have been exchanged and the connection is closed. Some hosts (notably web servers on Solaris) send TCP packets even after closing the connection. Increasing tcp.finwait (and possibly tcp.closing) can prevent blocking of such packets.

tcp.closed

The state after one endpoint sends an RST.

ICMP and UDP are handled in a fashion similar to TCP, but with a much more limited set of states:

udp.first

The state after the first packet.

udp.single

The state if the source host sends more than one packet but the destination host has never sent one back.

udp.multiple

The state if both hosts have sent packets.

icmp.first

The state after the first packet.

icmp.error

The state after an ICMP error came back in response to an ICMP packet.

Other protocols are handled similarly to UDP:

other.first

other.single

other.multiple

Timeout values can be reduced adaptively as the number of state table entries grows.

adaptive.start

When the number of state entries exceeds this value, adaptive scaling begins. All timeout values are scaled linearly with factor (adaptive.end - number of states) / (adaptive.end - adaptive.start).

adaptive.end

When reaching this number of state entries, all timeout values become zero, effectively purging all state entries immediately. This value is used to define the scale factor, it should not actually be reached (set a lower state limit, see below).

Adaptive timeouts are enabled by default, with an adaptive.start value equal to 60% of the state limit, and an adaptive.end value equal to 120% of the state limit. They can be disabled by setting both adaptive.start and adaptive.end to 0.

The adaptive timeout values can be defined both globally and for each rule. When used on a per-rule basis, the values relate to the number of states created by the rule, otherwise to the total number of states.

For example:

set timeout tcp.first 120
set timeout tcp.established 86400
set timeout { adaptive.start 6000, adaptive.end 12000 }
set limit states 10000

With 9000 state table entries, the timeout values are scaled to 50% (tcp.first 60, tcp.established 43200).

setloginterface

Enable collection of packet and byte count statistics for the given interface or interface group. These statistics can be viewed using

# pfctl -s info

In this example pf(4) collects statistics on the interface named dc0:

set loginterface dc0

One can disable the loginterface using:

set loginterface none

setlimit

Sets hard limits on the memory pools used by the packet filter. See pool(9) for an explanation of memory pools.

For example,

set limit states 20000

sets the maximum number of entries in the memory pool used by state table entries (generated by pass rules which do not specify nostate) to 20000. Using

set limit frags 20000

sets the maximum number of entries in the memory pool used for fragment reassembly (generated by scrub rules) to 20000. Using

set limit src-nodes 2000

sets the maximum number of entries in the memory pool used for tracking source IP addresses (generated by the sticky-address and src.track options) to 2000. Using

set limit tables 1000
set limit table-entries 100000

sets limits on the memory pools used by tables. The first limits the number of tables that can exist to 1000. The second limits the overall number of addresses that can be stored in tables to 100000.

Various limits can be combined on a single line:

set limit { states 20000, frags 20000, src-nodes 2000 }

setruleset-optimization

none

Disable the ruleset optimizer.

basic

Enable basic ruleset optimization. This is the default behaviour. Basic ruleset optimization does four things to improve the performance of ruleset evaluations:

1. remove duplicate rules
2. remove rules that are a subset of another rule
3. combine multiple rules into a table when advantageous
4. re-order the rules to improve evaluation performance

profile

Uses the currently loaded ruleset as a feedback profile to tailor the ordering of quick rules to actual network traffic.

It is important to note that the ruleset optimizer will modify the ruleset to improve performance. A side effect of the ruleset modification is that per-rule accounting statistics will have different meanings than before. If per-rule accounting is important for billing purposes or whatnot, either the ruleset optimizer should not be used or a label field should be added to all of the accounting rules to act as optimization barriers.

Optimization can also be set as a command-line argument to pfctl(8), overriding the settings in pf.conf.

setoptimization

Optimize state timeouts for one of the following network environments:

normal

A normal network environment. Suitable for almost all networks.

high-latency

A high-latency environment (such as a satellite connection).

satellite

Alias for high-latency.

aggressive

Aggressively expire connections. This can greatly reduce the memory usage of the firewall at the cost of dropping idle connections early.

conservative

Extremely conservative settings. Avoid dropping legitimate connections at the expense of greater memory utilization (possibly much greater on a busy network) and slightly increased processor utilization.

For example:

set optimization aggressive

setblock-policy

The block-policy option sets the default behaviour for the packet block action:

drop

Packet is silently dropped.

return

A TCP RST is returned for blocked TCP packets, an ICMP UNREACHABLE is returned for blocked UDP packets, and all other packets are silently dropped.

For example:

set block-policy return

setstate-policy

The state-policy option sets the default behaviour for states:

if-bound

States are bound to interface.

floating

States can match packets on any interfaces (the default).

For example:

set state-policy if-bound

sethostid

The 32-bit hostid identifies this firewall's state table entries to other firewalls in a pfsync(4) failover cluster. By default the hostid is set to a pseudo-random value, however it may be desirable to manually configure it, for example to more easily identify the source of state table entries.

set hostid 1

The hostid may be specified in either decimal or hexadecimal.

setrequire-order

By default pfctl(8) enforces an ordering of the statement types in the ruleset to: options, normalization, queueing, translation, filtering. Setting this option to no disables this enforcement. There may be non-trivial and non-obvious implications to an out of order ruleset. Consider carefully before disabling the order enforcement.

setfingerprints

Load fingerprints of known operating systems from the given filename. By default fingerprints of known operating systems are automatically loaded from pf.os(5) in /etc but can be overridden via this option. Setting this option may leave a small period of time where the fingerprints referenced by the currently active ruleset are inconsistent until the new ruleset finishes loading.

For example:

     set fingerprints \&"/etc/pf.os.devel\&"

setskip on ‹ifspec›

List interfaces for which packets should not be filtered. Packets passing in or out on such interfaces are passed as if pf was disabled, i.e. pf does not process them in any way. This can be useful on loopback and other virtual interfaces, when packet filtering is not desired and can have unexpected effects. For example:

     set skip on lo0

setdebug

Set the debug level to one of the following:

none

Don't generate debug messages.

urgent

Generate debug messages only for serious errors.

misc

Generate debug messages for various errors.

loud

Generate debug messages for common conditions.

TRAFFIC NORMALIZATION

no-df

Clears the dont-fragment bit from a matching IP packet. Some operating systems are known to generate fragmented packets with the dont-fragment bit set. This is particularly true with NFS. Scrub will drop such fragmented dont-fragment packets unless no-df is specified.

Unfortunately some operating systems also generate their dont-fragment packets with a zero IP identification field. Clearing the dont-fragment bit on packets with a zero IP ID may cause deleterious results if an upstream router later fragments the packet. Using the random-id modifier (see below) is recommended in combination with the no-df modifier to ensure unique IP identifiers.

min-ttl‹number›

Enforces a minimum TTL for matching IP packets.

max-mss‹number›

Enforces a maximum MSS for matching TCP packets.

\*(Ba ‹number› Enforces a TOS for matching IP packets. TOS may be given as one of lowdelay, throughput, reliability, or as either hex or decimal.

random-id

Replaces the IP identification field with random values to compensate for predictable values generated by many hosts. This option only applies to packets that are not fragmented after the optional fragment reassembly.

fragmentreassemble

Using scrub rules, fragments can be reassembled by normalization. In this case, fragments are buffered until they form a complete packet, and only the completed packet is passed on to the filter. The advantage is that filter rules have to deal only with complete packets, and can ignore fragments. The drawback of caching fragments is the additional memory cost. But the full reassembly method is the only method that currently works with NAT. This is the default behavior of a scrub rule if no fragmentation modifier is supplied.

fragmentcrop

The default fragment reassembly method is expensive, hence the option to crop is provided. In this case, pf(4) will track the fragments and cache a small range descriptor. Duplicate fragments are dropped and overlaps are cropped. Thus data will only occur once on the wire with ambiguities resolving to the first occurrence. Unlike the fragmentreassemble modifier, fragments are not buffered, they are passed as soon as they are received. The fragmentcrop reassembly mechanism does not yet work with NAT.

fragmentdrop-ovl

This option is similar to the fragmentcrop modifier except that all overlapping or duplicate fragments will be dropped, and all further corresponding fragments will be dropped as well.

reassembletcp

Statefully normalizes TCP connections. scrubreassemble tcp rules may not have the direction (in/out) specified. reassembletcp performs the following normalizations:

ttl

Neither side of the connection is allowed to reduce their IP TTL. An attacker may send a packet such that it reaches the firewall, affects the firewall state, and expires before reaching the destination host. reassembletcp will raise the TTL of all packets back up to the highest value seen on the connection.

timestamp modulation

Modern TCP stacks will send a timestamp on every TCP packet and echo the other endpoint's timestamp back to them. Many operating systems will merely start the timestamp at zero when first booted, and increment it several times a second. The uptime of the host can be deduced by reading the timestamp and multiplying by a constant. Also observing several different timestamps can be used to count hosts behind a NAT device. And spoofing TCP packets into a connection requires knowing or guessing valid timestamps. Timestamps merely need to be monotonically increasing and not derived off a guessable base time. reassembletcp will cause scrub to modulate the TCP timestamps with a random number.

extended PAWS checks

There is a problem with TCP on long fat pipes, in that a packet might get delayed for longer than it takes the connection to wrap its 32-bit sequence space. In such an occurrence, the old packet would be indistinguishable from a new packet and would be accepted as such. The solution to this is called PAWS: Protection Against Wrapped Sequence numbers. It protects against it by making sure the timestamp on each packet does not go backwards. reassembletcp also makes sure the timestamp on the packet does not go forward more than the RFC allows. By doing this, pf(4) artificially extends the security of TCP sequence numbers by 10 to 18 bits when the host uses appropriately randomized timestamps, since a blind attacker would have to guess the timestamp as well.

scrub in on $ext_if all fragment reassemble

QUEUEING

cbq

Class Based Queueing. Queues attached to an interface build a tree, thus each queue can have further child queues. Each queue can have a priority and a bandwidth assigned. Priority mainly controls the time packets take to get sent out, while bandwidth has primarily effects on throughput. cbq achieves both partitioning and sharing of link bandwidth by hierarchically structured classes. Each class has its own queue and is assigned its share of bandwidth. A child class can borrow bandwidth from its parent class as long as excess bandwidth is available (see the option borrow, below).

priq

Priority Queueing. Queues are flat attached to the interface, thus, queues cannot have further child queues. Each queue has a unique priority assigned, ranging from 0 to 15. Packets in the queue with the highest priority are processed first.

hfsc

Hierarchical Fair Service Curve. Queues attached to an interface build a tree, thus each queue can have further child queues. Each queue can have a priority and a bandwidth assigned. Priority mainly controls the time packets take to get sent out, while bandwidth primarily affects throughput. hfsc supports both link-sharing and guaranteed real-time services. It employs a service curve based QoS model, and its unique feature is an ability to decouple delay and bandwidth allocation.

‹interface›

Queueing is enabled on the named interface.

‹scheduler›

Specifies which queueing scheduler to use. Currently supported values are cbq for Class Based Queueing, priq for Priority Queueing and hfsc for the Hierarchical Fair Service Curve scheduler.

bandwidth‹bw›

The maximum bitrate for all queues on an interface may be specified using the bandwidth keyword. The value can be specified as an absolute value or as a percentage of the interface bandwidth. When using an absolute value, the suffixes b, Kb, Mb, and Gb are used to represent bits, kilobits, megabits, and gigabits per second, respectively. The value must not exceed the interface bandwidth. If bandwidth is not specified, the interface bandwidth is used (but take note that some interfaces do not know their bandwidth, or can adapt their bandwidth rates).

qlimit‹limit›

The maximum number of packets held in the queue. The default is 50.

tbrsize‹size›

Adjusts the size, in bytes, of the token bucket regulator. If not specified, heuristics based on the interface bandwidth are used to determine the size.

queue‹list›

Defines a list of subqueues to create on an interface.

altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh }

on‹interface›

Specifies the interface the queue operates on. If not given, it operates on all matching interfaces.

bandwidth‹bw›

Specifies the maximum bitrate to be processed by the queue. This value must not exceed the value of the parent queue and can be specified as an absolute value or a percentage of the parent queue's bandwidth. If not specified, defaults to 100% of the parent queue's bandwidth. The priq scheduler does not support bandwidth specification.

priority‹level›

Between queues a priority level can be set. For cbq and hfsc, the range is 0 to 7 and for priq, the range is 0 to 15. The default for all is 1. Priq queues with a higher priority are always served first. Cbq and Hfsc queues with a higher priority are preferred in the case of overload.

qlimit‹limit›

The maximum number of packets held in the queue. The default is 50.

default

Packets not matched by another queue are assigned to this one. Exactly one default queue is required.

red

Enable RED (Random Early Detection) on this queue. RED drops packets with a probability proportional to the average queue length.

rio

Enables RIO on this queue. RIO is RED with IN/OUT, thus running RED two times more than RIO would achieve the same effect. RIO is currently not supported in the GENERIC kernel.

ecn

Enables ECN (Explicit Congestion Notification) on this queue. ECN implies RED.

borrow

The queue can borrow bandwidth from the parent.

realtime‹sc›

The minimum required bandwidth for the queue.

upperlimit‹sc›

The maximum allowed bandwidth for the queue.

linkshare‹sc›

The bandwidth share of a backlogged queue.

queue std bandwidth 10% cbq(default)
queue http bandwidth 60% priority 2 cbq(borrow red) \e
      { employees, developers }
queue  developers bandwidth 75% cbq(borrow)
queue  employees bandwidth 15%
queue mail bandwidth 10% priority 0 cbq(borrow ecn)
queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk }
queue  ssh_interactive bandwidth 50% priority 7 cbq(borrow)
queue  ssh_bulk bandwidth 50% priority 0 cbq(borrow)

block return out on dc0 inet all queue std
pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e
      queue developers
pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e
      queue employees
pass out on dc0 inet proto tcp from any to any port 22 \e
      queue(ssh_bulk, ssh_interactive)
pass out on dc0 inet proto tcp from any to any port 25 \e
      queue mail

TRANSLATION

binat

A binat rule specifies a bidirectional mapping between an external IP netblock and an internal IP netblock.

nat

A nat rule specifies that IP addresses are to be changed as the packet traverses the given interface. This technique allows one or more IP addresses on the translating host to support network traffic for a larger range of machines on an "inside" network. Although in theory any IP address can be used on the inside, it is strongly recommended that one of the address ranges defined by RFC 1918 be used. These netblocks are:

10.0.0.0 - 10.255.255.255 (all of net 10, i.e., 10/8)
172.16.0.0 - 172.31.255.255 (i.e., 172.16/12)
192.168.0.0 - 192.168.255.255 (i.e., 192.168/16)

rdr

The packet is redirected to another destination and possibly a different port. rdr rules can optionally specify port ranges instead of single ports. rdr ... port 2000:2999 -\*(Gt ... port 4000 redirects ports 2000 to 2999 (inclusive) to port 4000. rdr ... port 2000:2999 -\*(Gt ... port 4000:* redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999.

rdr on ne3 inet proto tcp to port smtp -\*(Gt 127.0.0.1 port spamd

PACKET FILTERING

block

The packet is blocked. There are a number of ways in which a block rule can behave when blocking a packet. The default behaviour is to drop packets silently, however this can be overridden or made explicit either globally, by setting the block-policy option, or on a per-rule basis with one of the following options:

drop

The packet is silently dropped.

return-rst

This applies only to tcp(4) packets, and issues a TCP RST which closes the connection.

return-icmp

return-icmp6

This causes ICMP messages to be returned for packets which match the rule. By default this is an ICMP UNREACHABLE message, however this can be overridden by specifying a message as a code or number.

return

This causes a TCP RST to be returned for tcp(4) packets and an ICMP UNREACHABLE for UDP and other packets.

Options returning ICMP packets currently have no effect if pf(4) operates on a bridge(4), as the code to support this feature has not yet been implemented.

The simplest mechanism to block everything by default and only pass packets that match explicit rules is specify a first filter rule of:

block all

pass

The packet is passed; state is created unless the nostate option is specified.

pass out inet proto icmp all icmp-type echoreq

PARAMETERS

inor out

This rule applies to incoming or outgoing packets. If neither in nor out are specified, the rule will match packets in both directions.

log

In addition to the action specified, a log message is generated. Only the packet that establishes the state is logged, unless the nostate option is specified. The logged packets are sent to a pflog(4) interface, by default pflog0. This interface is monitored by the pflogd(8) logging daemon, which dumps the logged packets to the file /var/log/pflog in pcap(3) binary format.

log(all)

Used to force logging of all packets for a connection. This is not necessary when nostate is explicitly specified. As with log, packets are logged to pflog(4).

log(user)

Logs the .Ux user ID of the user that owns the socket and the PID of the process that has the socket open where the packet is sourced from or destined to (depending on which socket is local). This is in addition to the normal information logged.

log(to ‹interface›)

Send logs to the specified pflog(4) interface instead of pflog0.

quick

If a packet matches a rule which has the quick option set, this rule is considered the last matching rule, and evaluation of subsequent rules is skipped.

on‹interface›

This rule applies only to packets coming in on, or going out through, this particular interface or interface group. For more information on interface groups, see the group keyword in ifconfig(8).

‹af›

This rule applies only to packets of this address family. Supported values are inet and inet6.

proto‹protocol›

This rule applies only to packets of this protocol. Common protocols are icmp(4), icmp6(4), tcp(4), and udp(4). For a list of all the protocol name to number mappings used by pfctl(8), see the file /etc/protocols.

from‹source› port‹source› os‹source› to‹dest› port‹dest› This rule applies only to packets with the specified source and destination addresses and ports.

Addresses can be specified in CIDR notation (matching netblocks), as symbolic host names, interface names or interface group names, or as any of the following keywords:

any

Any address.

route‹label›

Any address whose associated route has label ‹label›. See route(4) and route(8).

no-route

Any address which is not currently routable.

urpf-failed

Any source address that fails a unicast reverse path forwarding (URPF) check, i.e. packets coming in on an interface other than that which holds the route back to the packet's source address.

‹table›

Any address that matches the given table.

Ranges of addresses are specified by using the ‘-’ operator. For instance: “10.1.1.10 - 10.1.1.12” means all addresses from 10.1.1.10 to 10.1.1.12, hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12.

Interface names and interface group names can have modifiers appended:

:network

Translates to the network(s) attached to the interface.

:broadcast

Translates to the interface's broadcast address(es).

:peer

Translates to the point to point interface's peer address(es).

:0

Do not include interface aliases.

Host names may also have the :0 option appended to restrict the name resolution to the first of each v4 and v6 address found.

Host name resolution and interface to address translation are done at ruleset load-time. When the address of an interface (or host name) changes (under DHCP or PPP, for instance), the ruleset must be reloaded for the change to be reflected in the kernel. Surrounding the interface name (and optional modifiers) in parentheses changes this behaviour. When the interface name is surrounded by parentheses, the rule is automatically updated whenever the interface changes its address. The ruleset does not need to be reloaded. This is especially useful with nat.

Ports can be specified either by number or by name. For example, port 80 can be specified as www. For a list of all port name to number mappings used by pfctl(8), see the file /etc/services.

Ports and ranges of ports are specified by using these operators:

=	(equal)
!=	(unequal)
\*(Lt	(less than)
\*(Le	(less than or equal)
\*(Gt	(greater than)
\*(Ge	(greater than or equal)
:	(range including boundaries)
\*(Gt\*(Lt	(range excluding boundaries)
\*(Lt\*(Gt	(except range)

‘\*(Gt\*(Lt’, ‘\*(Lt\*(Gt’ and ‘\&:’ are binary operators (they take two arguments). For instance:

port2000:2004

means ‘all ports \*(Ge 2000 and \*(Le 2004’, hence ports 2000, 2001, 2002, 2003 and 2004.

port2000 \*(Gt\*(Lt 2004

means ‘all ports \*(Gt 2000 and \*(Lt 2004’, hence ports 2001, 2002 and 2003.

port2000 \*(Lt\*(Gt 2004

means ‘all ports \*(Lt 2000 or \*(Gt 2004’, hence ports 1-1999 and 2005-65535.

The operating system of the source host can be specified in the case of TCP rules with the OS modifier. See the section for more information.

The host, port and OS specifications are optional, as in the following examples:

pass in all
pass in from any to any
pass in proto tcp from any port \*(Le 1024 to any
pass in proto tcp from any to any port 25
pass in proto tcp from 10.0.0.0/8 port \*(Gt 1024 \e
      to ! 10.1.2.3 port != ssh
pass in proto tcp from any os "OpenBSD"
pass in proto tcp from route "DTAG"

all

This is equivalent to "from any to any".

group‹group›

Similar to user, this rule only applies to packets of sockets owned by the specified group.

user‹user›

This rule only applies to packets of sockets owned by the specified user. For outgoing connections initiated from the firewall, this is the user that opened the connection. For incoming connections to the firewall itself, this is the user that listens on the destination port. For forwarded connections, where the firewall is not a connection endpoint, the user and group are unknown.

All packets, both outgoing and incoming, of one connection are associated with the same user and group. Only TCP and UDP packets can be associated with users; for other protocols these parameters are ignored.

User and group refer to the effective (as opposed to the real) IDs, in case the socket is created by a setuid/setgid process. User and group IDs are stored when a socket is created; when a process creates a listening socket as root (for instance, by binding to a privileged port) and subsequently changes to another user ID (to drop privileges), the credentials will remain root.

User and group IDs can be specified as either numbers or names. The syntax is similar to the one for ports. The value unknown matches packets of forwarded connections. unknown can only be used with the operators -= and -!=. Other constructs like -user\*(Ge unknown are invalid. Forwarded packets with unknown user and group ID match only rules that explicitly compare against unknown with the operators -= or -!=. For instance -user\*(Ge 0 does not match forwarded packets. The following example allows only selected users to open outgoing connections:

block out proto { tcp, udp } all
pass  out proto { tcp, udp } all user { \*(Lt 1000, dhartmei }

.Pf / Ns Aq Ar b \*(Ba / \*(Ba any This rule only applies to TCP packets that have the flags ‹a› set out of set ‹b›. Flags not specified in ‹b› are ignored. For stateful connections, the default is flagsS/SA. To indicate that flags should not be checked at all, specify flagsany. The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R.

flagsS/S

Flag SYN is set. The other flags are ignored.

flagsS/SA

This is the default setting for stateful connections. Out of SYN and ACK, exactly SYN may be set. SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. This is more restrictive than the previous example.

flags/SFRA

If the first set is not specified, it defaults to none. All of SYN, FIN, RST and ACK must be unset.

Because flagsS/SA is applied by default (unless nostate is specified), only the initial SYN packet of a TCP handshake will create a state for a TCP connection. It is possible to be less restrictive, and allow state creation from intermediate (non-SYN) packets, by specifying flagsany. This will cause pf(4) to synchronize to existing connections, for instance if one flushes the state table. However, states created from such intermediate packets may be missing connection details such as the TCP window scaling factor. States which modify the packet flow, such as those affected by nat, binat or rdr rules, modulateor synproxystate options, or scrubbed with reassembletcp will also not be recoverable from intermediate packets. Such connections will stall and time out.

code‹code›

code‹code› This rule only applies to ICMP or ICMPv6 packets with the specified type and code. Text names for ICMP types and codes are listed in icmp(4) and icmp6(4). This parameter is only valid for rules that cover protocols ICMP or ICMP6. The protocol and the ICMP type indicator ( icmp-type or icmp6-type ) must match.

\*(Ba ‹number› This rule applies to packets with the specified TOS bits set. TOS may be given as one of lowdelay, throughput, reliability, or as either hex or decimal.

For example, the following rules are identical:

pass all tos lowdelay
pass all tos 0x10
pass all tos 16

allow-opts

By default, IPv4 packets with IP options or IPv6 packets with routing extension headers are blocked. When allow-opts is specified for a pass rule, packets that pass the filter based on that rule (last matching) do so even if they contain IP options or routing extension headers. For packets that match state, the rule that initially created the state is used. The implicit pass rule that is used when a packet does not match any rules does not allow IP options.

label‹string›

Adds a label (name) to the rule, which can be used to identify the rule. For instance, pfctl -s labels shows per-rule statistics for rules that have labels.

The following macros can be used in labels:

$if

The interface.

$srcaddr

The source IP address.

$dstaddr

The destination IP address.

$srcport

The source port specification.

$dstport

The destination port specification.

$proto

The protocol name.

$nr

The rule number.

For example:

ips = \&"{ 1.2.3.4, 1.2.3.5 }\&"
pass in proto tcp from any to $ips \e
      port \*(Gt 1023 label \&"$dstaddr:$dstport\&"

expands to

pass in inet proto tcp from any to 1.2.3.4 \e
      port \*(Gt 1023 label \&"1.2.3.4:\*(Gt1023\&"
pass in inet proto tcp from any to 1.2.3.5 \e
      port \*(Gt 1023 label \&"1.2.3.5:\*(Gt1023\&"

The macro expansion for the label directive occurs only at configuration file parse time, not during runtime.

\*(Ba ( ‹queue›, ‹queue›) Packets matching this rule will be assigned to the specified queue. If two queues are given, packets which have a TOS of lowdelay and TCP ACKs with no data payload will be assigned to the second one. See for setup details.

For example:

pass in proto tcp to port 25 queue mail
pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio)

tag‹string›

Packets matching this rule will be tagged with the specified string. The tag acts as an internal marker that can be used to identify these packets later on. This can be used, for example, to provide trust between interfaces and to determine if packets have been processed by translation rules. Tags are "sticky", meaning that the packet will be tagged even if the rule is not the last matching rule. Further matching rules can replace the tag with a new one but will not remove a previously applied tag. A packet is only ever assigned one tag at a time. Packet tagging can be done during nat, rdr, or binat rules in addition to filter rules. Tags take the same macros as labels (see above).

tagged‹string›

Used with filter, translation or scrub rules to specify that packets must already be tagged with the given tag in order to match the rule. Inverse tag matching can also be done by specifying the -!\& operator before the tagged keyword.

rtable‹number›

Used to select an alternate routing table for the routing lookup. Only effective before the route lookup happened, i.e. when filtering inbound.

port‹port› Used to redirect packets to a local socket bound to host and port. The packets will not be modified, so getsockname(2) on the socket will return the original destination address of the packet.

divert-reply

Used to receive replies for sockets that are bound to addresses which are not local to the machine. See setsockopt(2) for information on how to bind these sockets.

probability‹number›

A probability attribute can be attached to a rule, with a value set between 0 and 1, bounds not included. In that case, the rule will be honoured using the given probability value only. For example, the following rule will drop 20% of incoming ICMP packets:

block in proto icmp probability 20%

ROUTING

fastroute

The fastroute option does a normal route lookup to find the next hop for the packet.

route-to

The route-to option routes the packet to the specified interface with an optional address for the next hop. When a route-to rule creates state, only packets that pass in the same direction as the filter rule specifies will be routed in this way. Packets passing in the opposite direction (replies) are not affected and are routed normally.

reply-to

The reply-to option is similar to route-to, but routes packets that pass in the opposite direction (replies) to the specified interface. Opposite direction is only defined in the context of a state entry, and reply-to is useful only in rules that create state. It can be used on systems with multiple external connections to route all outgoing packets of a connection through the interface the incoming connection arrived through (symmetric routing enforcement).

dup-to

The dup-to option creates a duplicate of the packet and routes it like route-to. The original packet gets routed as it normally would.

POOL OPTIONS

bitmask

The bitmask option applies the network portion of the redirection address to the address to be modified (source with nat, destination with rdr)).

random

The random option selects an address at random within the defined block of addresses.

source-hash

The source-hash option uses a hash of the source address to determine the redirection address, ensuring that the redirection address is always the same for a given source. An optional key can be specified after this keyword either in hex or as a string; by default pfctl(8) randomly generates a key for source-hash every time the ruleset is reloaded.

round-robin

The round-robin option loops through the redirection address(es).

When more than one redirection address is specified, round-robin is the only permitted pool type.

static-port

With nat rules, the static-port option prevents pf(4) from modifying the source port on TCP and UDP packets.

STATE MODULATION

block all
pass out proto tcp from any to any modulate state
pass in  proto tcp from any to any port 25 flags S/SFRA modulate state

SYN PROXY

pass in proto tcp from any to any port www synproxy state

STATEFUL TRACKING OPTIONS

max‹number›

Limits the number of concurrent states the rule may create. When this limit is reached, further packets that would create state will not match this rule until existing states time out.

no-sync

Prevent state changes for states created by this rule from appearing on the pfsync(4) interface.

‹seconds› Changes the timeout values used for states created by this rule. For a list of all valid timeout names, see above.

sloppy

Uses a sloppy TCP connection tracker that does not check sequence numbers at all, which makes insertion and ICMP teardown attacks way easier. This is intended to be used in situations where one does not see all packets of a connection, e.g. in asymmetric routing situations. Cannot be used with modulate or synproxy state.

pass in proto tcp from any to any \e
      port www keep state \e
      (max 100, source-track rule, max-src-nodes 75, \e
      max-src-states 3, tcp.established 60, tcp.closing 5)

source-trackrule

The maximum number of states created by this rule is limited by the rule's max-src-nodes and max-src-states options. Only state entries created by this particular rule count toward the rule's limits.

source-trackglobal

The number of states created by all rules that use this option is limited. Each rule can specify different max-src-nodes and max-src-states options, however state entries created by any participating rule count towards each individual rule's limits.

max-src-nodes‹number›

Limits the maximum number of source addresses which can simultaneously have state table entries.

max-src-states‹number›

Limits the maximum number of simultaneous state entries that a single source address can create with this rule.

max-src-conn‹number›

Limits the maximum number of simultaneous TCP connections which have completed the 3-way handshake that a single host can make.

/ ‹seconds› Limit the rate of new connections over a time interval. The connection rate is an approximation calculated as a moving average.

block quick from \*(Ltbad_hosts\*(Gt
pass in on $ext_if proto tcp to $webserver port www keep state \e
	(max-src-conn-rate 100/10, overload \*(Ltbad_hosts\*(Gt flush global)

OPERATING SYSTEM FINGERPRINTING

pass  out proto tcp from any os OpenBSD
block out proto tcp from any os Doors
block out proto tcp from any os "Doors PT"
block out proto tcp from any os "Doors PT SP3"
block out from any os "unknown"
pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0"

BLOCKING SPOOFED TRAFFIC

antispoof for lo0

block drop in on ! lo0 inet from 127.0.0.1/8 to any
block drop in on ! lo0 inet6 from ::1 to any

antispoof for wi0 inet

block drop in on ! wi0 inet from 10.0.0.0/24 to any
block drop in inet from 10.0.0.1 to any

FRAGMENT HANDLING

pass in proto tcp from any to any port 80

ANCHORS

nat-anchor‹name›

Evaluates the nat rules in the specified anchor.

rdr-anchor‹name›

Evaluates the rdr rules in the specified anchor.

binat-anchor‹name›

Evaluates the binat rules in the specified anchor.

anchor‹name›

Evaluates the filter rules in the specified anchor.

‹name› from‹file› Loads the rules from the specified file into the anchor name.

ext_if = \&"kue0\&"
block on $ext_if all
anchor spam
pass out on $ext_if all
pass in on $ext_if proto tcp from any \e
      to $ext_if port smtp

# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e
      pfctl -a spam -f -

anchor spam
load anchor spam from "/etc/pf-spam.conf"

block on $ext_if all
anchor spam proto tcp from any to any port smtp
pass out on $ext_if all
pass in on $ext_if proto tcp from any to $ext_if port smtp

# echo \&"block in quick from 1.2.3.4 to any" \&| \e
      pfctl -a spam -f -

anchor "spam/*"

# echo ' anchor "spam/allowed" ' | pfctl -f -
# echo -e ' anchor "../banned" \en pass' | \e
      pfctl -a spam/allowed -f -

anchor "external" on egress {
	block
	anchor out {
		pass proto tcp from any to port { 25, 80, 443 }
	}
	pass in proto tcp to any port 22
}

TRANSLATION EXAMPLES

# use a macro for the interface name, so it can be changed easily
ext_if = \&"ne3\&"

# map daemon on 8080 to appear to be on 80
rdr on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 port 8080

rdr pass on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 \e
      port 8080

nat on ! vlan12 from 192.168.168.0/24 to any -\*(Gt 204.92.77.111

# NO NAT
no nat on $ext_if proto ah from 144.19.74.0/24 to any
nat on $ext_if from 144.19.74.0/24 to any -\*(Gt 204.92.77.100

# NO RDR
no rdr on $int_if proto { tcp, udp } from any to $server port 80
no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80
rdr on $int_if proto { tcp, udp } from any to any port 80 -\*(Gt 127.0.0.1 \e
      port 80

# NAT
# Translate outgoing packets' source addresses (any protocol).
# In this case, any address but the gateway's external address is mapped.
nat on $ext_if inet from ! ($ext_if) to any -\*(Gt ($ext_if)

# NAT PROXYING
# Map outgoing packets' source port to an assigned proxy port instead of
# an arbitrary port.
# In this case, proxy outgoing isakmp with port 500 on the gateway.
nat on $ext_if inet proto udp from any port = isakmp to any -\*(Gt ($ext_if) \e
      port 500

# BINAT
# Translate outgoing packets' source address (any protocol).
# Translate incoming packets' destination address to an internal machine
# (bidirectional).
binat on $ext_if from 10.1.2.150 to any -\*(Gt $ext_if

# RDR
# Translate incoming packets' destination addresses.
# As an example, redirect a TCP and UDP port to an internal machine.
rdr on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e
      -\*(Gt 10.1.2.151 port 22
rdr on $ext_if inet proto udp from any to ($ext_if) port 8080 \e
      -\*(Gt 10.1.2.151 port 53

# RDR
# Translate outgoing ftp control connections to send them to localhost
# for proxying with ftp-proxy(8) running on port 8021.
rdr on $int_if proto tcp from any to any port 21 -\*(Gt 127.0.0.1 port 8021

# NAT LOAD BALANCE
# Translate outgoing packets' source addresses using an address pool.
# A given source address is always translated to the same pool address by
# using the source-hash keyword.
nat on $ext_if inet from any to any -\*(Gt 192.0.2.16/28 source-hash

# RDR ROUND ROBIN
# Translate incoming web server connections to a group of web servers on
# the internal network.
rdr on $ext_if proto tcp from any to any port 80 \e
      -\*(Gt { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin

FILTER EXAMPLES

# The external interface is kue0
# (157.161.48.183, the only routable address)
# and the private network is 10.0.0.0/8, for which we are doing NAT.

# use a macro for the interface name, so it can be changed easily
ext_if = \&"kue0\&"

# normalize all incoming traffic
scrub in on $ext_if all fragment reassemble

# block and log everything by default
block return log on $ext_if all

# block anything coming from source we have no back routes for
block in from no-route to any

# block packets whose ingress interface does not match the one in
# the route back to their source address
block in from urpf-failed to any

# block and log outgoing packets that do not have our address as source,
# they are either spoofed or something is misconfigured (NAT disabled,
# for instance), we want to be nice and do not send out garbage.
block out log quick on $ext_if from ! 157.161.48.183 to any

# silently drop broadcasts (cable modem noise)
block in quick on $ext_if from any to 255.255.255.255

# block and log incoming packets from reserved address space and invalid
# addresses, they are either spoofed or misconfigured, we cannot reply to
# them anyway (hence, no return-rst).
block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e
      192.168.0.0/16, 255.255.255.255/32 } to any

# ICMP

# pass out/in certain ICMP queries and keep state (ping)
# state matching is done on host addresses and ICMP id (not type/code),
# so replies (like 0/0 for 8/0) will match queries
# ICMP error messages (which always refer to a TCP/UDP packet) are
# handled by the TCP/UDP states
pass on $ext_if inet proto icmp all icmp-type 8 code 0

# UDP

# pass out all UDP connections and keep state
pass out on $ext_if proto udp all

# pass in certain UDP connections and keep state (DNS)
pass in on $ext_if proto udp from any to any port domain

# TCP

# pass out all TCP connections and modulate state
pass out on $ext_if proto tcp all modulate state

# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT)
pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e
      auth }

# Do not allow Windows 9x SMTP connections since they are typically
# a viral worm. Alternately we could limit these OSes to 1 connection each.
block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e
      to any port smtp

# IPv6
# pass in/out all IPv6 traffic: note that we have to enable this in two
# different ways, on both our physical interface and our tunnel
pass quick on gif0 inet6
pass quick on $ext_if proto ipv6

# Packet Tagging

# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is
# being done on $ext_if for all outgoing packets. tag packets in on
# $int_if and pass those tagged packets out on $ext_if.  all other
# outgoing packets (i.e., packets from the wireless network) are only
# permitted to access port 80.

pass in on $int_if from any to any tag INTNET
pass in on $wifi_if from any to any

block out on $ext_if from any to any
pass out quick on $ext_if tagged INTNET
pass out on $ext_if proto tcp from any to any port 80

# tag incoming packets as they are redirected to spamd(8). use the tag
# to pass those packets through the packet filter.

rdr on $ext_if inet proto tcp from \*(Ltspammers\*(Gt to port smtp \e
	tag SPAMD -\*(Gt 127.0.0.1 port spamd

block in on $ext_if
pass in on $ext_if inet proto tcp tagged SPAMD

GRAMMAR

line           = ( option | pf-rule | nat-rule | binat-rule | rdr-rule |
                 antispoof-rule | altq-rule | queue-rule | trans-anchors |
                 anchor-rule | anchor-close | load-anchor | table-rule |
                 include )

option         = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] |
                 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] |
                 [ "optimization" [ "default" | "normal" |
                 "high-latency" | "satellite" |
                 "aggressive" | "conservative" ] ]
                 [ "limit" ( limit-item | "{" limit-list "}" ) ] |
                 [ "loginterface" ( interface-name | "none" ) ] |
                 [ "block-policy" ( "drop" | "return" ) ] |
                 [ "state-policy" ( "if-bound" | "floating" ) ]
                 [ "require-order" ( "yes" | "no" ) ]
                 [ "fingerprints" filename ] |
                 [ "skip on" ifspec ] |
                 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] )

pf-rule        = action [ ( "in" | "out" ) ]
                 [ "log" [ "(" logopts ")"] ] [ "quick" ]
                 [ "on" ifspec ] [ "fastroute" | route ] [ af ] [ protospec ]
                 hosts [ filteropt-list ]

logopts        = logopt [ "," logopts ]
logopt         = "all" | "user" | "to" interface-name

filteropt-list = filteropt-list filteropt | filteropt
filteropt      = user | group | flags | icmp-type | icmp6-type | "tos" tos |
                 ( "no" | "keep" | "modulate" | "synproxy" ) "state"
                 [ "(" state-opts ")" ] |
                 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos |
                 "max-mss" number | "random-id" | "reassemble tcp" |
                 fragmentation | "allow-opts" |
                 "label" string | "tag" string | [ ! ] "tagged" string |
                 "queue" ( string | "(" string [ [ "," ] string ] ")" ) |
                 "rtable" number | "probability" number"%"

nat-rule       = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ]
                 [ "on" ifspec ] [ af ]
                 [ protospec ] hosts [ "tag" string ] [ "tagged" string ]
                 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" )
                 [ portspec ] [ pooltype ] [ "static-port" ] ]

binat-rule     = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ]
                 [ "on" interface-name ] [ af ]
                 [ "proto" ( proto-name | proto-number ) ]
                 "from" address [ "/" mask-bits ] "to" ipspec
                 [ "tag" string ] [ "tagged" string ]
                 [ "-\*(Gt" address [ "/" mask-bits ] ]

rdr-rule       = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ]
                 [ "on" ifspec ] [ af ]
                 [ protospec ] hosts [ "tag" string ] [ "tagged" string ]
                 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" )
                 [ portspec ] [ pooltype ] ]

antispoof-rule = "antispoof" [ "log" ] [ "quick" ]
                 "for" ifspec [ af ] [ "label" string ]

table-rule     = "table" "\*(Lt" string "\*(Gt" [ tableopts-list ]
tableopts-list = tableopts-list tableopts | tableopts
tableopts      = "persist" | "const" | "counters" | "file" string |
                 "{" [ tableaddr-list ] "}"
tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec
tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ]
tableaddr      = hostname | ifspec | "self" |
                 ipv4-dotted-quad | ipv6-coloned-hex

altq-rule      = "altq on" interface-name queueopts-list
                 "queue" subqueue
queue-rule     = "queue" string [ "on" interface-name ] queueopts-list
                 subqueue

anchor-rule    = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ]
                 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ]

anchor-close   = "}"

trans-anchors  = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string
                 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ]

load-anchor    = "load anchor" string "from" filename

queueopts-list = queueopts-list queueopts | queueopts
queueopts      = [ "bandwidth" bandwidth-spec ] |
                 [ "qlimit" number ] | [ "tbrsize" number ] |
                 [ "priority" number ] | [ schedulers ]
schedulers     = ( cbq-def | priq-def | hfsc-def )
bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" )

action         = "pass" | "block" [ return ] | [ "no" ] "scrub"
return         = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] |
                 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] |
                 "return-icmp6" [ "(" icmp6code ")" ]
icmpcode       = ( icmp-code-name | icmp-code-number )
icmp6code      = ( icmp6-code-name | icmp6-code-number )

ifspec         = ( [ "!" ] ( interface-name | interface-group ) ) |
                 "{" interface-list "}"
interface-list = [ "!" ] ( interface-name | interface-group )
                 [ [ "," ] interface-list ]
route          = ( "route-to" | "reply-to" | "dup-to" )
                 ( routehost | "{" routehost-list "}" )
                 [ pooltype ]
af             = "inet" | "inet6"

protospec      = "proto" ( proto-name | proto-number |
                 "{" proto-list "}" )
proto-list     = ( proto-name | proto-number ) [ [ "," ] proto-list ]

hosts          = "all" |
                 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host |
                 "{" host-list "}" | "route" string ) [ port ] [ os ]
                 "to"   ( "any" | "no-route" | "self" | host |
                 "{" host-list "}" | "route" string ) [ port ]

ipspec         = "any" | host | "{" host-list "}"
host           = [ "!" ] ( address [ "/" mask-bits ] | "\*(Lt" string "\*(Gt" )
redirhost      = address [ "/" mask-bits ]
routehost      = "(" interface-name [ address [ "/" mask-bits ] ] ")"
address        = ( interface-name | interface-group |
                 "(" ( interface-name | interface-group ) ")" |
                 hostname | ipv4-dotted-quad | ipv6-coloned-hex )
host-list      = host [ [ "," ] host-list ]
redirhost-list = redirhost [ [ "," ] redirhost-list ]
routehost-list = routehost [ [ "," ] routehost-list ]

port           = "port" ( unary-op | binary-op | "{" op-list "}" )
portspec       = "port" ( number | name ) [ ":" ( "*" | number | name ) ]
os             = "os"  ( os-name | "{" os-list "}" )
user           = "user" ( unary-op | binary-op | "{" op-list "}" )
group          = "group" ( unary-op | binary-op | "{" op-list "}" )

unary-op       = [ "=" | "!=" | "\*(Lt" | "\*(Le" | "\*(Gt" | "\*(Ge" ]
                 ( name | number )
binary-op      = number ( "\*(Lt\*(Gt" | "\*(Gt\*(Lt" | ":" ) number
op-list        = ( unary-op | binary-op ) [ [ "," ] op-list ]

os-name        = operating-system-name
os-list        = os-name [ [ "," ] os-list ]

flags          = "flags" ( [ flag-set ] "/"  flag-set | "any" )
flag-set       = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ]
                 [ "W" ]

icmp-type      = "icmp-type" ( icmp-type-code | "{" icmp-list "}" )
icmp6-type     = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" )
icmp-type-code = ( icmp-type-name | icmp-type-number )
                 [ "code" ( icmp-code-name | icmp-code-number ) ]
icmp-list      = icmp-type-code [ [ "," ] icmp-list ]

tos            = ( "lowdelay" | "throughput" | "reliability" |
                 [ "0x" ] number )

state-opts     = state-opt [ [ "," ] state-opts ]
state-opt      = ( "max" number | "no-sync" | timeout | sloppy |
                 "source-track" [ ( "rule" | "global" ) ] |
                 "max-src-nodes" number | "max-src-states" number |
                 "max-src-conn" number |
                 "max-src-conn-rate" number "/" number |
                 "overload" "\*(Lt" string "\*(Gt" [ "flush" ] |
                 "if-bound" | "floating" )

fragmentation  = [ "fragment reassemble" | "fragment crop" |
                 "fragment drop-ovl" ]

timeout-list   = timeout [ [ "," ] timeout-list ]
timeout        = ( "tcp.first" | "tcp.opening" | "tcp.established" |
                 "tcp.closing" | "tcp.finwait" | "tcp.closed" |
                 "udp.first" | "udp.single" | "udp.multiple" |
                 "icmp.first" | "icmp.error" |
                 "other.first" | "other.single" | "other.multiple" |
                 "frag" | "interval" | "src.track" |
                 "adaptive.start" | "adaptive.end" ) number

limit-list     = limit-item [ [ "," ] limit-list ]
limit-item     = ( "states" | "frags" | "src-nodes" ) number

pooltype       = ( "bitmask" | "random" |
                 "source-hash" [ ( hex-key | string-key ) ] |
                 "round-robin" ) [ sticky-address ]

subqueue       = string | "{" queue-list "}"
queue-list     = string [ [ "," ] string ]
cbq-def        = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ]
priq-def       = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ]
hfsc-def       = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ]
cbq-opt        = ( "default" | "borrow" | "red" | "ecn" | "rio" )
priq-opt       = ( "default" | "red" | "ecn" | "rio" )
hfsc-opt       = ( "default" | "red" | "ecn" | "rio" |
                 linkshare-sc | realtime-sc | upperlimit-sc )
linkshare-sc   = "linkshare" sc-spec
realtime-sc    = "realtime" sc-spec
upperlimit-sc  = "upperlimit" sc-spec
sc-spec        = ( bandwidth-spec |
                 "(" bandwidth-spec number bandwidth-spec ")" )
include        = "include" filename

FILES

/etc/hosts

Host name database.

/etc/pf.conf

Default location of the ruleset file.

/etc/pf.os

Default location of OS fingerprints.

/etc/protocols

Protocol name database.

/etc/services

Service name database.

SEE ALSO

HISTORY