NAME

DESCRIPTION

PACKET FILTERING

including network address translation (NAT).

OPTIONS

globally tune the behaviour of the packet filtering engine.

QUEUEING

provides rule-based bandwidth and traffic control.

TABLES

provide a method for dealing with large numbers of addresses.

ANCHORS

are containers for rules and tables.

STATEFUL FILTERING

tracks packets by state.

TRAFFIC NORMALISATION

includes scrub, fragment handling, and blocking spoofed traffic.

OPERATING SYSTEM FINGERPRINTING

is a method for detecting a host's operating system.

EXAMPLES

provides some example rulesets.

GRAMMAR

provides a complete BNF grammar reference.

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

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

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

This causes a TCP RST to be returned for TCP packets and an ICMP UNREACHABLE for other types of packets.

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-rst

This applies only to TCP packets, and issues a TCP RST which closes the connection. An optional parameter, ttl, may be given with a TTL value.

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

 

 

match

The packet is matched. This mechanism is used to provide fine grained filtering without altering the block/pass state of a packet. match rules differ from block and pass rules in that parameters are set every time a packet matches the rule, not only on the last matching rule. For the following parameters, this means that the parameter effectively becomes “sticky” until explicitly overridden: nat-to, binat-to, rdr-to, queue, rtable, and scrub.

log is different still, in that the action happens every time a rule matches i.e. a single packet can get logged more than once.

 

 

pass

The packet is passed; state is created unless the no state option is specified.

 

 

in or out

A packet always comes in on, or goes out through, one interface. in and out apply to incoming and outgoing packets; if neither are specified, the rule will match packets in both directions.

 

 

log (all | matches | to interface | user)

In addition to any action specified, log the packet. Only the packet that establishes the state is logged, unless the no state option is specified. The logged packets are sent to a pflog(4) interface, by default pflog0; pflog0 is monitored by the pflogd(8) logging daemon which logs to the file /var/log/pflog in pcap(3) binary format.

The keywords all, matches, to, and user are optional and can be combined using commas, but must be enclosed in parentheses if given.

Use all to force logging of all packets for a connection. This is not necessary when no state is explicitly specified.

If matches is specified, it logs the packet on all subsequent matching rules. It is often combined with to interface to avoid adding noise to the default log file.

The keyword user logs the UID and PID of the socket on the local host used to send or receive a packet, in addition to the normal information.

To specify a logging interface other than pflog0, use the syntax to interface.

 

 

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 | any

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). any will match any existing interface except loopback ones.

 

 

on rdomain number

This rule applies only to packets coming in on, or going out through, this particular routing domain.

 

 

inet | inet6

This rule applies only to packets of this address family.

 

 

proto protocol

This rule applies only to packets of this protocol. Common protocols are ICMP, ICMP6, TCP, and UDP. 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.

no-route

Any address which is not currently routable.

route label

Any address matching the given route(8) label.

self

Expands to all addresses assigned to all interfaces.

<table>

Any address matching the given table.

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.

Ranges of addresses are specified 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, interface group names, and self can have modifiers appended:

:0

Do not include interface aliases.

:broadcast

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

:network

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

:peer

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

Host names may also have the :0 modifier 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 using these operators:

=	(equal) 
!=	(unequal) 
<	(less than) 
<=	(less than or equal) 
>	(greater than) 
>=	(greater than or equal) 
:	(range including boundaries) 
><	(range excluding boundaries) 
<>	(except range)
    

‘><’, ‘<>’ and ‘:’ are binary operators (they take two arguments). For instance:

 

 

port 2000:2004

means ‘all ports ≥ 2000 and ≤ 2004’, hence ports 2000, 2001, 2002, 2003, and 2004.

 

 

port 2000 >< 2004

means ‘all ports > 2000 and < 2004’, hence ports 2001, 2002, and 2003.

 

 

port 2000 <> 2004

means ‘all ports < 2000 or > 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 OPERATING SYSTEM FINGERPRINTING 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 < 1024 to any 
pass in proto tcp from any to any port 25 
pass in proto tcp from 10.0.0.0/8 port >= 1024 \ 
      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’.

allow-opts

By default, packets with IPv4 options or IPv6 hop-by-hop or destination options header 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 options. 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 or option headers. Note that IPv6 packets with type 0 routing headers are always dropped.

divert-packet port port

Used to send matching packets to divert(4) sockets bound to port port. If the default option of fragment reassembly is enabled, scrubbing with reassemble tcp is also enabled for divert-packet rules.

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.

divert-to host 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.

flags a/b | 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 flags S/SA. To indicate that flags should not be checked at all, specify flags any. The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R.

 

 

flags S/S

Flag SYN is set. The other flags are ignored.

 

 

flags S/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 flags S/SA is applied by default (unless no state 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 flags any. 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 af-to, modulate state, nat-to, rdr-to, or synproxy state options, or scrubbed with reassemble tcp, will also not be recoverable from intermediate packets. Such connections will stall and time out.

group group

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

icmp-type type code code

 

icmp6-type type code code

This rule only applies to ICMP or ICMP6 packets with the specified type and code. Text names for ICMP types and codes are listed in icmp(4) and icmp6(4). The protocol and the ICMP type indicator (icmp-type or icmp6-type) must match.

label string

Adds a label 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:

$dstaddr

The destination IP address.

$dstport

The destination port specification.

$if

The interface.

$nr

The rule number.

$proto

The protocol name.

$srcaddr

The source IP address.

$srcport

The source port specification.

For example:

ips = "{ 1.2.3.4, 1.2.3.5 }" 
pass in proto tcp from any to $ips \ 
      port > 1023 label "$dstaddr:$dstport"
    

Expands to:

pass in inet proto tcp from any to 1.2.3.4 \ 
      port > 1023 label "1.2.3.4:>1023" 
pass in inet proto tcp from any to 1.2.3.5 \ 
      port > 1023 label "1.2.3.5:>1023"
    

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

max-pkt-rate number/seconds

Measure the rate of packets matching the rule and states created by it. When the specified rate is exceeded, the rule stops matching. Only packets in the direction in which the state was created are considered, so that typically requests are counted and replies are not. For example, to pass up to 100 ICMP packets per 10 seconds:

block in proto icmp 
pass in proto icmp max-pkt-rate 100/10
    

When the rate is exceeded, all ICMP is blocked until the rate falls below 100 per 10 seconds again.

once

Creates a one shot rule that will remove itself from an active ruleset after the first match. In case this is the only rule in the anchor, the anchor will be destroyed automatically after the rule is matched.

probability number%

A probability attribute can be attached to a rule, with a value set between 0 and 100%, in which case the rule is honoured using the given probability value. For example, the following rule will drop 20% of incoming ICMP packets:

block in proto icmp probability 20%

prio number

Only match packets which have the given queueing priority assigned.

[

!

]received-on interface

Only match packets which were received on the specified interface (or interface group). any will match any existing interface except loopback ones.

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.

set delay milliseconds

Packets matching this rule will be delayed at the outbound interface by the given number of milliseconds.

set prio priority | (priority, priority)

Packets matching this rule will be assigned a specific queueing priority. Priorities are assigned as integers 0 through 7, with a default priority of 3. If the packet is transmitted on a vlan(4) interface, the queueing priority will also be written as the priority code point in the 802.1Q VLAN header. If two priorities are given, TCP ACKs with no data payload and packets which have a TOS of lowdelay will be assigned to the second one. Packets with a higher priority number are processed first, and packets with the same priority are processed in the order in which they are received.

For example:

pass in proto tcp to port 25 set prio 2 
pass in proto tcp to port 22 set prio (2, 5)
    

The interface priority queues accessed by the set prio keyword are always enabled and do not require any additional configuration, unlike the queues described below and in the QUEUEING section.

set queue queue | (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 QUEUEING for setup details.

For example:

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

set tos string | number

Enforces a TOS for matching packets. string may be one of critical, inetcontrol, lowdelay, netcontrol, throughput, reliability, or one of the DiffServ Code Points: ef, af11 ... af43, cs0 ... cs7; number may be either a hex or decimal number.

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. Tags take the same macros as labels (see above).

[

!

]tagged string

Used with filter or translation rules to specify that packets must already be tagged with the given string in order to match the rule.

tos string | number

This rule applies to packets with the specified TOS bits set. string may be one of critical, inetcontrol, lowdelay, netcontrol, throughput, reliability, or one of the DiffServ Code Points: ef, af11 ... af43, cs0 ... cs7; number may be either a hex or decimal number.

For example, the following rules are identical:

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

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.

When listening sockets are bound to the wildcard address, pf(4) cannot determine if a connection is destined for the firewall itself. To avoid false matches on just the destination port, combine a user rule with source or destination address self.

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.

The user and group arguments 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 following example allows only selected users to open outgoing connections:

block out proto tcp all 
pass  out proto tcp from self user { < 1000, dhartmei }
    

Translation

 

 

af-to

Translation between different address families (NAT64) is handled using af-to rules. Because address family translation overrides the routing table, it's only possible to use af-to on inbound rules, and a source address for the resulting translation must always be specified.

The optional second argument is the host or subnet the original addresses are translated into for the destination. The lowest bits of the original destination address form the host part of the new destination address according to the specified subnet. It is possible to embed a complete IPv4 address into an IPv6 address using a network prefix of /96 or smaller.

When a destination address is not specified it is assumed that the host part is 32-bit long. For IPv6 to IPv4 translation this would mean using only the lower 32 bits of the original IPv6 destination address. For IPv4 to IPv6 translation the destination subnet defaults to the subnet of the new IPv6 source address with a prefix length of /96. See RFC 6052 Section 2.2 for details on how the prefix determines the destination address encoding.

For example, the following rules are identical:

pass in inet af-to inet6 from 2001:db8::1 to 2001:db8::/96 
pass in inet af-to inet6 from 2001:db8::1
    

In the above example the matching IPv4 packets will be modified to have a source address of 2001:db8::1 and a destination address will get prefixed with 2001:db8::/96, e.g. 198.51.100.100 will be translated to 2001:db8::c633:6464.

In the reverse case the following rules are identical:

pass in inet6 from any to 64:ff9b::/96 af-to inet \ 
	from 198.51.100.1 to 0.0.0.0/0 
pass in inet6 from any to 64:ff9b::/96 af-to inet \ 
	from 198.51.100.1
    

The destination IPv4 address is assumed to be embedded inside the original IPv6 destination address, e.g. 64:ff9b::c633:6464 will be translated to 198.51.100.100.

The current implementation will only extract IPv4 addresses from the IPv6 addresses with a prefix length of /96 and greater.

 

 

binat-to

A binat-to rule specifies a bidirectional mapping between an external IP netblock and an internal IP netblock. It expands to an outbound nat-to rule and an inbound rdr-to rule.

 

 

nat-to

A nat-to option 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. Those 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)
    

nat-to is usually applied outbound. If applied inbound, nat-to to a local IP address is not supported.

 

 

rdr-to

The packet is redirected to another destination and possibly a different port. rdr-to can optionally specify port ranges instead of single ports. For instance:

 

 

match in ... port 2000:2999 rdr-to ... port 4000

redirects ports 2000 to 2999 (inclusive) to port 4000.

 

 

match in ... port 2000:2999 rdr-to ... port 4000:*

redirects port 2000 to 4000, port 2001 to 4001, ..., port 2999 to 4999.

rdr-to is usually applied inbound. If applied outbound, rdr-to to a local IP address is not supported.

pass in on $int_if proto tcp from $int_net to $ext_if port 80 \ 
	rdr-to $server 
pass out on $int_if proto tcp to $server port 80 \ 
	received-on $int_if nat-to $int_if

pass in on egress proto tcp from any to any port smtp \ 
	rdr-to 127.0.0.1 port spamd

 

 

bitmask

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

 

 

least-states [

sticky-address

]

The least-states option selects the address with the least active states from a given address pool and considers given weights associated with address(es). Weights can be specified between 1 and 65535. Addresses with higher weights are selected more often.

sticky-address can be specified to ensure that multiple connections from the same source are mapped to the same redirection address. Associations are destroyed as soon as there are no longer states which refer to them; in order to make the mappings last beyond the lifetime of the states, increase the global options with set timeout src.track.

 

 

random [

sticky-address

]

The random option selects an address at random within the defined block of addresses. sticky-address is as described above.

 

 

round-robin [

sticky-address

]

The round-robin option loops through the redirection address(es) and considers given weights associated with address(es). Weights can be specified between 1 and 65535. Addresses with higher weights are selected more often. sticky-address is as described above.

 

 

source-hash [

key

]

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.

 

 

static-port

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

Routing

 

 

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.

 

 

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).

 

 

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.

OPTIONS

 

 

set block-policy drop | return

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.

 

 

set debug level

Set the debug level, which limits the severity of log messages printed by pf(4). This should be a keyword from the following ordered list (highest to lowest): emerg, alert, crit, err, warning, notice, info, and debug. These keywords correspond to the similar (LOG_) values specified to the syslog(3) library routine.

 

 

set fingerprints filename

Load fingerprints of known operating systems from the given filename. By default fingerprints of known operating systems are automatically loaded from pf.os(5), 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.

 

 

set hostid number

The 32-bit hostid number 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. The hostid may be specified in either decimal or hexadecimal.

 

 

set limit limit-item number

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

For example, to set the maximum number of entries in the memory pool used by state table entries (generated by pass rules which do not specify no state) to 20000:

set limit states 20000

To set the maximum number of entries in the memory pool used for fragment reassembly to 2000:

set limit frags 2000

This maximum may not exceed, and should be well below, the maximum number of mbuf clusters (sysctl kern.maxclusters) in the system.

To set 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:

set limit src-nodes 2000

To set limits on the memory pools used by tables:

set limit tables 1000 
set limit table-entries 100000
    

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 2000, src-nodes 2000 }
    

 

 

set loginterface interface | none

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

 

 

set optimization environment

Optimize state timeouts for one of the following network environments:

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.

high-latency

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

normal

A normal network environment. Suitable for almost all networks.

satellite

Alias for high-latency.

 

 

set reassemble yes | no [

no-df

]

The reassemble option is used to enable or disable the reassembly of fragmented packets, and can be set to yes (the default) or no. If no-df is also specified, fragments with the “dont-fragment” bit set are reassembled too, instead of being dropped; the reassembled packet will have the “dont-fragment” bit cleared.

 

 

set ruleset-optimization level

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. reorder the rules to improve evaluation performance

none

Disable the ruleset optimizer.

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.

 

 

set skip 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. ifspec is only evaluated when the ruleset is loaded; interfaces created later will not be skipped.

 

 

set state-defaults state-option, ...

The state-defaults option sets the state options for states created from rules without an explicit keep state. For example:

set state-defaults pflow, no-sync

 

 

set state-policy if-bound | floating

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

if-bound

States are bound to an interface.

floating

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

 

 

set syncookies never | always | adaptive

When syncookies are active, pf will answer each and every incoming TCP SYN with a syncookie SYNACK, without allocating any resources. Upon reception of the client's ACK in response to the syncookie SYNACK, pf will evaluate the ruleset and create state if the ruleset permits it, complete the three way handshake with the target host, and continue the connection with synproxy in place. This allows pf to be resilient against large synflood attacks, which could otherwise exhaust the state table. Due to the blind answers to each and every SYN, syncookies share the caveats of synproxy: seemingly accepting connections that will be dropped later on.

never

pf will never send syncookie SYNACKs (the default).

always

pf will always send syncookie SYNACKs.

adaptive

pf will enable syncookie mode when a given percentage of the state table is used up by half-open TCP connections, such as those that saw the initial SYN but didn't finish the three way handshake. The thresholds for entering and leaving syncookie mode can be specified using:

set syncookies adaptive (start 25%, end 12%)
        

 

 

set timeout variable value

frag

Seconds before an unassembled fragment is expired.

interval

Interval between purging expired states and fragments.

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 protocol and 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.closed

The state after one endpoint sends an RST.

tcp.closing

The state after the first FIN has been sent.

tcp.established

The fully established state.

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.first

The state after the first packet.

tcp.opening

The state after the second packet but before both endpoints have acknowledged the connection.

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

icmp.error

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

icmp.first

The state after the first packet.

udp.first

The state after the first packet.

udp.multiple

The state if both hosts have sent packets.

udp.single

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

Other protocols are handled similarly to UDP:

other.first

 

other.multiple

 

other.single

 

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

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.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 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 60000, adaptive.end 120000 } 
set limit states 100000
    

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

QUEUEING

queue std on em0 bandwidth 100M 
queue ssh parent std bandwidth 10M 
queue mail parent std bandwidth 10M 
queue http parent std bandwidth 80M default

queue outq on em0 bandwidth 9M max 9M flows 1024 qlimit 1024 \ 
      default

 

 

default

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

 

 

on interface

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

 

 

parent name

Defines which parent queue the queue should be attached to. Mandatory for all queues except root queues. The parent queue must exist.

 

 

quantum size

Specifies the quantum of service for the flow queue manager. The lower the quantum size the more advantage is given to streams of smaller packets at the expense of bulk transfers. The default value is set to the configured Maximum Transmission Unit (MTU) of the specified interface.

 

 

qlimit limit

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

queue rootq on em0 bandwidth 100M max 100M 
queue http parent rootq bandwidth 60M burst 90M for 100ms 
queue  developers parent http bandwidth 45M 
queue  employees parent http bandwidth 15M 
queue mail parent rootq bandwidth 10M 
queue ssh parent rootq bandwidth 20M 
queue  ssh_interactive parent ssh bandwidth 10M min 5M 
queue  ssh_bulk parent ssh bandwidth 10M 
queue std parent rootq bandwidth 20M default 
 
block return out on em0 inet all set queue std 
pass out on em0 inet proto tcp from $developerhosts to any port 80 \ 
      set queue developers 
pass out on em0 inet proto tcp from $employeehosts to any port 80 \ 
      set queue employees 
pass out on em0 inet proto tcp from any to any port 22 \ 
      set queue(ssh_bulk, ssh_interactive) 
pass out on em0 inet proto tcp from any to any port 25 \ 
      set queue mail

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.

 

 

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).

 

 

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.

table <private> const { 10/8, 172.16/12, 192.168/16 } 
table <badhosts> persist 
block on fxp0 from { <private>, <badhosts> } to any

table <spam> persist file "/etc/spammers" file "/etc/openrelays" 
block on fxp0 from <spam> to any

ANCHORS

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 to $ext_if port smtp

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

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

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 
}

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" | pfctl -a spam -f -

 

 

anchor name

Evaluates the filter rules in the specified anchor.

anchor "spam/*"

# printf 'anchor "spam/allowed"\n' | pfctl -f - 
# printf 'anchor "../banned"\npass\n' | pfctl -a spam/allowed -f -

STATEFUL FILTERING

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

floating

States can match packets on any interfaces (the opposite of if-bound). This is the default.

if-bound

States are bound to an interface (the opposite of floating).

max number

Limits the number of concurrent states the rule may create. When this limit is reached, further packets that would create state are dropped until existing states time out.

no-sync

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

pflow

States created by this rule are exported on the pflow(4) interface.

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. It cannot be used with modulate state or synproxy state.

timeout seconds

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

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

source-track global

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.

source-track rule

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.

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.

max-src-conn-rate number/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 <bad_hosts> 
pass in on $ext_if proto tcp to $webserver port www keep state \ 
      (max-src-conn-rate 100/10, overload <bad_hosts> flush global)

TRAFFIC NORMALISATION

Scrub

 

 

max-mss number

Enforces a maximum segment size (MSS) for matching TCP packets.

 

 

min-ttl number

Enforces a minimum TTL for matching IP packets.

 

 

no-df

Clears the “dont-fragment” bit from a matching IPv4 packet. Some operating systems have NFS implementations which are known to generate fragmented packets with the “dont-fragment” bit set. pf(4) 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 random-id is recommended in combination with no-df to ensure unique IP identifiers.

 

 

random-id

Replaces the IPv4 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.

 

 

reassemble tcp

Statefully normalises TCP connections. reassemble tcp performs the following normalisations:

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. reassemble tcp 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. reassemble tcp 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. reassemble tcp 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.

Fragment Handling

pass in proto tcp from any to any port 80

Blocking Spoofed Traffic

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

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

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"

EXAMPLES

ext_if = "kue0" 
match in all scrub (no-df max-mss 1440) 
block return log on $ext_if all

block in from no-route to any 
block in from urpf-failed to any 
block out log quick on $ext_if from ! 157.161.48.183 to any 
block in quick on $ext_if from any to 255.255.255.255 
block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \ 
    192.168.0.0/16, 255.255.255.255/32 } to any

pass on $ext_if inet proto icmp all icmp-type 8 code 0

pass out on $ext_if proto udp all 
pass in on $ext_if proto udp from any to any port domain

pass out on $ext_if proto tcp all modulate state 
pass in on $ext_if proto tcp from any to any \ 
    port { ssh, smtp, domain, auth } 
block in on $ext_if proto tcp from any \ 
    os { "Windows 95", "Windows 98" } to any port smtp

pass quick on gif0 inet6 
pass quick on $ext_if proto ipv6

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

match in on $ext_if inet proto tcp from <spammers> to port smtp \ 
     tag SPAMD rdr-to 127.0.0.1 port spamd 
 
block in on $ext_if 
pass in on $ext_if inet proto tcp tagged SPAMD

match in on $ext_if proto tcp from any to any port 80 \ 
      rdr-to 127.0.0.1 port 8080

pass in quick on $ext_if proto tcp from any to any port 80 \ 
      rdr-to 127.0.0.1 port 8080

match out on ! vlan12 from 192.168.168.0/24 to any nat-to 204.92.77.111

pass out on $ext_if from 144.19.74.0/24 nat-to 204.92.77.100 
pass out on $ext_if proto ah from 144.19.74.0/24

pass in on $int_if proto { tcp, udp } from any to any port 80 \ 
      rdr-to 127.0.0.1 port 80 
pass in on $int_if proto { tcp, udp } from any to $server port 80 
pass in on $int_if proto { tcp, udp } from $sysadmins to any port 80

match out on $ext_if inet proto udp from any port isakmp to any \ 
    nat-to ($ext_if) port 500

match in on $ext_if inet proto tcp from any to ($ext_if) port 8080 \ 
      rdr-to 10.1.2.151 port 22 
match in on $ext_if inet proto udp from any to ($ext_if) port 8080 \ 
      rdr-to 10.1.2.151 port 53

match out on $ext_if inet from any to any nat-to 192.0.2.16/28 \ 
    source-hash 
match in  on $ext_if proto tcp from any to any port 80 \ 
    rdr-to { 10.1.2.155 weight 2, 10.1.2.160 weight 1, \ 
             10.1.2.161 weight 8 } round-robin

pass on $ext_if from 10.1.2.120 to any binat-to 192.0.2.17

pass out on $ext_if inet from 10.1.2.120 to any \ 
      nat-to 192.0.2.17 static-port 
pass in on $ext_if inet from any to 192.0.2.17 rdr-to 10.1.2.120

pass in on $v4_if inet af-to inet6 from ($v6_if) to 64:ff9b::/96

pass in on $v6_if inet6 to 64:ff9b::/96 af-to inet from ($v4_if)

GRAMMAR

line           = ( option | pf-rule | 
                 antispoof-rule | queue-rule | 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" ) ] 
                 [ "state-defaults" state-opts ] 
                 [ "fingerprints" filename ] | 
                 [ "skip on" ifspec ] | 
                 [ "debug" ( "emerg" | "alert" | "crit" | "err" | 
                 "warning" | "notice" | "info" | "debug" ) ] | 
                 [ "reassemble" ( "yes" | "no" ) [ "no-df" ] ] ) 
 
pf-rule        = action [ ( "in" | "out" ) ] 
                 [ "log" [ "(" logopts ")"] ] [ "quick" ] 
                 [ "on" ( ifspec | "rdomain" number ) ] [ af ] 
                 [ protospec ] [ hosts ] [ filteropts ] 
 
logopts        = logopt [ [ "," ] logopts ] 
logopt         = "all" | "matches" | "user" | "to" interface-name 
 
filteropts     = filteropt [ [ "," ] filteropts ] 
filteropt      = user | group | flags | icmp-type | icmp6-type | 
                 "tos" tos | 
                 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 
                 [ "(" state-opts ")" ] | "scrub" "(" scrubopts ")" | 
                 "fragment" | "allow-opts" | "once" | 
                 "divert-packet" "port" port | "divert-reply" | 
                 "divert-to" host "port" port | 
                 "label" string | "tag" string | [ "!" ] "tagged" string | 
                 "max-pkt-rate" number "/" seconds | 
                 "set delay" number | 
                 "set prio" ( number | "(" number [ [ "," ] number ] ")" ) | 
                 "set queue" ( string | "(" string [ [ "," ] string ] ")" ) | 
                 "rtable" number | "probability" number"%" | "prio" number | 
                 "af-to" af "from" ( redirhost | "{" redirhost-list "}" ) 
                 [ "to" ( redirhost | "{" redirhost-list "}" ) ] | 
                 "binat-to" ( redirhost | "{" redirhost-list "}" ) 
                 [ portspec ] [ pooltype ] | 
                 "rdr-to" ( redirhost | "{" redirhost-list "}" ) 
                 [ portspec ] [ pooltype ] | 
                 "nat-to" ( redirhost | "{" redirhost-list "}" ) 
                 [ portspec ] [ pooltype ] [ "static-port" ] | 
                 [ route ] | [ "set tos" tos ] | 
                 [ [ "!" ] "received-on" ( interface-name | interface-group ) ] 
 
scrubopts      = scrubopt [ [ "," ] scrubopts ] 
scrubopt       = "no-df" | "min-ttl" number | "max-mss" number | 
                 "reassemble tcp" | "random-id" 
 
antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 
                 "for" ifspec [ af ] [ "label" string ] 
 
table-rule     = "table" "<" string ">" [ tableopts ] 
tableopts      = tableopt [ tableopts ] 
tableopt       = "persist" | "const" | "counters" | 
                 "file" string | "{" [ tableaddrs ] "}" 
tableaddrs     = tableaddr-spec [ [ "," ] tableaddrs ] 
tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 
tableaddr      = hostname | ifspec | "self" | 
                 ipv4-dotted-quad | ipv6-coloned-hex 
 
queue-rule     = "queue" string [ "on" interface-name ] queueopts-list 
 
anchor-rule    = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 
                 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 
 
anchor-close   = "}" 
 
load-anchor    = "load anchor" string "from" filename 
 
queueopts-list = queueopts-list queueopts | queueopts 
queueopts      = ([ "bandwidth" bandwidth ] | [ "min" bandwidth ] | 
                 [ "max" bandwidth ] | [ "parent" string ] | 
                 [ "default" ]) | 
                 ([ "flows" number ] | [ "quantum" number ]) | 
                 [ "qlimit" number ] 
 
bandwidth      = bandwidth-spec [ "burst" bandwidth-spec "for" number "ms" ] 
bandwidth-spec = number ( "" | "K" | "M" | "G" ) 
 
action         = "pass" | "match" | "block" [ return ] 
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 [ "weight" number ] | 
                 address [ "/" mask-bits ] [ "weight" number ] | 
                 "<" string ">" ) 
redirhost      = address [ "/" mask-bits ] 
routehost      = host | host "@" interface-name | 
                 "(" 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       = [ "=" | "!=" | "<" | "<=" | ">" | ">=" ] 
                 ( name | number ) 
binary-op      = number ( "<>" | "><" | ":" ) 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" | 
                 "pflow" | "source-track" [ ( "rule" | "global" ) ] | 
                 "max-src-nodes" number | "max-src-states" number | 
                 "max-src-conn" number | 
                 "max-src-conn-rate" number "/" number | 
                 "overload" "<" string ">" [ "flush" [ "global" ] ] | 
                 "if-bound" | "floating" ) 
 
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" | "tables" | 
                 "table-entries" ) number 
 
pooltype       = ( "bitmask" | "least-states" | 
                 "random" | "round-robin" | 
                 "source-hash" [ ( hex-key | string-key ) ] ) 
                 [ "sticky-address" ] 
 
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