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authorTheo de Raadt <deraadt@cvs.openbsd.org>2002-11-25 04:05:52 +0000
committerTheo de Raadt <deraadt@cvs.openbsd.org>2002-11-25 04:05:52 +0000
commite9e43e31b213ce9f6f907c373e61d161fbd1a8ef (patch)
tree7b1392f66697169c038d53a83f8d773eca182025 /share/man/man5
parent2436866e8b2b5da8a2a8c6b7627195e3b75d23f1 (diff)
another pass, sigh
Diffstat (limited to 'share/man/man5')
-rw-r--r--share/man/man5/pf.conf.5152
1 files changed, 78 insertions, 74 deletions
diff --git a/share/man/man5/pf.conf.5 b/share/man/man5/pf.conf.5
index c02c2cc8d1a..323bd8aa04e 100644
--- a/share/man/man5/pf.conf.5
+++ b/share/man/man5/pf.conf.5
@@ -1,4 +1,4 @@
-.\" $OpenBSD: pf.conf.5,v 1.120 2002/11/25 03:44:12 henning Exp $
+.\" $OpenBSD: pf.conf.5,v 1.121 2002/11/25 04:05:51 deraadt Exp $
.\"
.\" Copyright (c) 2002, Daniel Hartmeier
.\" All rights reserved.
@@ -205,17 +205,17 @@ These can be combined:
Optimize the engine to one of the following network topographies or
environments:
.Bl -tag -width "O high-latency " -compact
-.It Em default
+.It Pa default
A normal network environment.
Suitable for almost all networks.
-.It Em normal
+.It Pa normal
Alias for
-.Em default
+.Pa default
.It Em high-latency
A high-latency environment (such as a satellite connection)
-.It Em satellite
+.It Pa satellite
Alias for
-.Em high-latency
+.Pa high-latency
.It Em aggressive
Aggressively expire connections when they are likely no longer valid.
This can greatly reduce the memory usage of the firewall at the cost of
@@ -234,9 +234,9 @@ For example:
.Ed
.It Pa set block-policy
The
-.Em block-policy
+.Pa block-policy
option sets the default behaviour for the
-.Em block
+.Pa block
action:
.Bl -tag -width return -compact
.It Em drop
@@ -260,7 +260,7 @@ translation,
.Pa queue ,
filter.
Setting this option to
-.Em no
+.Pa no
disables this enforcement.
One has to be very careful about the implications of an out of order
ruleset.
@@ -333,24 +333,24 @@ At least two rules are required to configure queues, and later
any basic filtering or NAT rule can reference the defined
queues by name.
The queue name last referenced is where any packets from
-.Em pass
+.Pa pass
rules will be queued, while for
-.Em block
+.Pa block
rules it specifies where any resulting
-.Em icmp
+.Pa icmp
or
-.Em TCP RST
+.Pa TCP RST
packets should be enqueued.
.Pp
-.Em altq on
+.Pa altq on
specifies on which interface queues will be set up.
The
-.Em scheduler
+.Pa scheduler
type is required where currently only CBQ is supported.
-.Em bandwidth
+.Pa bandwidth
is optional and specifies the maximum rate for all queues on this interface.
All queues for this interface have to be listed after
-.Em queue .
+.Pa queue .
.Pp
In the following example, the interface
.Pa dc0
@@ -360,21 +360,21 @@ should queue up to 5 Mbit/s in two queues using CBQ.
.Ed
.Pp
Parameters for the queues are specified in
-.Em queue
+.Pa queue
rules. The queuename must match the definition in the
-.Em altq
+.Pa altq
rule.
-.Em bandwidth
+.Pa bandwidth
sets the maximum bitrate that can be processed by this queue.
The value must not exceed the value of the parent queue and can be specified
in absolute and percentage values.
Between queues a
-.Em priority
+.Pa priority
level can be set.
The range is 0..7 with a default of 1.
Queues with a higher priority level are preferred in the case of overload.
The scheduler can get additional parameters with
-.Em cbq( <parameters> ) .
+.Pa cbq( <parameters> ) .
Parameters are as follows:
.Pp
.Bl -tag -width Fl
@@ -399,7 +399,7 @@ ECN implies RED.
.El
.Pp
Furthermore child queues can be specified like in an
-.Em altq
+.Pa altq
rule.
.Pp
Following the previous example, this would specify the two referenced
@@ -440,7 +440,7 @@ Each rule either matches the packet or doesn't.
The last matching rule decides what action is taken.
.Pp
If no rule matches the packet, the default action is
-.Em pass .
+.Pa pass .
.Pp
To block everything by default and only pass packets
that match explicit rules, one uses
@@ -477,12 +477,12 @@ or to the firewall itself.
.It Em block
The packet is blocked.
There are a number of ways in which a
-.Em block
+.Pa block
rule can behave when blocking a packet. The default behaviour is to
-.Em drop
+.Pa drop
packets silently, however this can be overridden or made explicit
globally by setting the
-.Em block-policy
+.Pa block-policy
option, or on a per-rule basis with the following options:
.Pp
.Bl -tag -width "return-icmp6" -compact -offset indent
@@ -508,12 +508,12 @@ Scrub rules are not considered last matching rules.
IPv6 packets are not defragmented.
.It Em binat
A
-.Em binat
+.Pa binat
rule specifies a bidirectional mapping between an external IP netblock
and an internal IP netblock.
.It Em nat
A
-.Em nat
+.Pa 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
@@ -530,7 +530,7 @@ These netblocks are:
.It Em rdr
The packet is redirected to another destination and possibly a
different port.
-.Em rdr
+.Pa rdr
rules can optionally specify port ranges instead of single ports.
\'rdr ... port 2000:2999 -> ... port 4000\' redirects ports 2000 to 2999
(including port 2000 and 2999) to the same port 4000.
@@ -550,9 +550,9 @@ generates all needed rule combinations:
.It Pa in No or Pa out
The rule applies to incoming or outgoing packets.
Either
-.Em in
+.Pa in
or
-.Em out
+.Pa out
must be specified.
To cover both directions, two rules are needed.
.It Em log
@@ -565,7 +565,7 @@ interface.
This interface is monitored by the
.Xr pflogd 8
logging daemon which dumps the logged packets to the file
-.Em /var/log/pflog
+.Pa /var/log/pflog
in
.Xr pcap 3
binary format.
@@ -656,7 +656,7 @@ For incoming connections to the firewall itself, this is the user that
listens on the destination port.
For forwarded connections, where the firewall isn't a connection endpoint,
the user and group are
-.Em unknown .
+.Pa unknown .
.Pp
All packets, both outgoing and incoming, of one connection are associated
with the same user and group.
@@ -673,14 +673,14 @@ user ID (to drop privileges), the socket's uid remains root.
User and group IDs can be specified as either numbers or names, the
syntax is similar to the one for ports.
The value
-.Em unknown
+.Pa unknown
matches packets of forwarded connections.
-.Em unknown
+.Pa unknown
can only be used with operators = and !=, other constructs
like 'user >= unknown' are invalid.
Forwarded packets with unknown user and group ID match only rules
that explicitly compare against
-.Em unknown
+.Pa unknown
with operator = or !=, for instance 'user >= 0' does not match
forwarded packets.
The following example allows only selected users to open outgoing
@@ -717,21 +717,21 @@ must match.
.It Pa allow-opts
By default, packets which contain IP options are blocked.
When
-.Em allow-opts
+.Pa allow-opts
is specified for a
-.Em pass
+.Pa pass
rule, packets that pass the filter based on that rule (last matching)
do so even if they contain IP options.
For packets that match state, the rule that initially created the
state is used.
The implicit
-.Em pass
+.Pa pass
rule that is used when a packet doesn't match any rules does not
allow IP options.
.It Pa label <string>
Adds a label (name) to the rule, which can be used to identify the rule.
For instance,
-.Em pfctl -s labels
+.Pa pfctl -s labels
shows per-rule statistics for rules that have labels.
.Pp
The following macros can be used in labels:
@@ -786,50 +786,50 @@ packets matching the same connection.
.Bl -tag -width xxxx
.It Pa fastroute
The
-.Em fastroute
+.Pa fastroute
option does a normal route lookup to find the next hop for the packet.
.It Pa route-to
The
-.Em route-to
+.Pa route-to
option routes the packet to the specified interface with an optional address
for the next hop.
When a
-.Em route-to
+.Pa 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 routed normally.
.It Pa reply-to
The
-.Em reply-to
+.Pa reply-to
option is similar to
-.Em route-to
+.Pa route-to
but routes packets that pass in the opposite direction (replies) to the
specified interface.
Opposite direction is only defined in context of a state entry, and
-.Em route-to
+.Pa route-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).
.It Pa dup-to
The
-.Em dup-to
+.Pa dup-to
option creates a duplicate of the packet and routes it like
-.Em route-to.
+.Pa route-to.
The original packet gets routed as it normally would.
.El
.Pp
.Sh POOL OPTIONS
For
-.Em nat
+.Pa nat
and
-.Em rdr
+.Pa rdr
rules, (as well as for the
-.Em route-to ,
-.Em reply-to
+.Pa route-to ,
+.Pa reply-to
and
-.Em dup-to
+.Pa dup-to
rule options) for which there is a single redirection address which has a
subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP
address), a variety of different methods for assigning this address can be
@@ -837,47 +837,47 @@ used:
.Bl -tag -width xxxx
.It Em bitmask
The
-.Em bitmask
+.Pa bitmask
option applies the network portion of the redirection address to the address
to be modified (source with nat, destination with rdr).
.It Em random
The
-.Em random
+.Pa random
option selects an address at random within the defined block of addresses.
.It Em source-hash
The
-.Em source-hash
+.Pa 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.
The option can additionally be modified as follows:
.Bl -tag -width "random" -compact -offset indent
.It Em key
The
-.Em key
+.Pa key
option for
-.Em source-hash
+.Pa source-hash
allows one to specify a string used by pfctl to generate a key which is hashed
in with the source address.
.It Em random
The
-.Em random
+.Pa random
option for
-.Em source-hash
+.Pa source-hash
randomly generates a key for source-hash every time the ruleset is reloaded.
.El
.It Em round-robin
The
-.Em round-robin
+.Pa round-robin
option loops through the redirection address(s).
.Pp
When more than one redirection address is specified,
-.Em round-robin
+.Pa round-robin
is the only permitted pool type.
.It Pa static-port
With
-.Em nat
+.Pa nat
rules, the
-.Em static-port
+.Pa static-port
option prevents
.Xr pf 4
from modifying the source port on tcp and udp packets.
@@ -951,7 +951,7 @@ state and get passed.
For ICMP queries, keep state creates an ICMP state, and
.Xr pf 4
knows how to match ICMP replies to states.
-For example
+For example,
.Bd -literal
pass out inet proto icmp all icmp-type echoreq keep state
.Ed
@@ -1028,7 +1028,7 @@ For a list of all valid timeout names, see
Multiple options can be specified, separated by commas:
.Bd -literal
pass in proto tcp from any to any port www flags S/SA \\
- keep state (max 100, tcp.established 60, tcp.closing 5)
+ keep state (max 100, tcp.established 60, tcp.closing 5)
.Ed
.Sh BLOCKING SPOOFED TRAFFIC
"Spoofing" is the faking of IP addresses, typically for malicious
@@ -1077,8 +1077,8 @@ Every packet seen there is sent from and to the local host.
One may want to include these rules at the very beginning
of their ruleset to pass all traffic on lo0:
.Bd -literal
-pass in quick on lo0 all
-pass out quick on lo0 all
+ pass in quick on lo0 all
+ pass out quick on lo0 all
.Ed
.Sh FRAGMENT HANDLING
The size of IP datagrams (packets) can be significantly larger than the
@@ -1094,7 +1094,7 @@ to filter on things such as TCP ports or to perform NAT.
There are four options for handling fragments in the packet filter:
.Pp
Use scrub rules. See the section on
-.Em TRAFFIC NORMALIZATION.
+.Pa TRAFFIC NORMALIZATION.
.Pp
The alternative is to filter individual fragments with filter rules.
If no
@@ -1113,10 +1113,14 @@ fragments but not complete packets.
Filter rules without the
.Pa fragment
option still apply to fragments, if they only specify IP header fields.
-For instance, the rule 'pass in proto tcp from any to any port 80' never
-applies to a fragment, even if the fragment is part of a TCP packet with
-destination port 80, because without reassembly, this information is not
-available for each fragment.
+For instance, the rule
+.Pp
+.Bd -literal
+ pass in proto tcp from any to any port 80
+.Ed
+.Pp never applies to a fragment, even if the fragment is part of a TCP
+packet with destination port 80, because without reassembly, this information
+is not available for each fragment.
This also means that fragments can't create new or match existing
state table entries, which makes stateful filtering and address
translations (NAT, redirection) for fragments impossible.