blocklist/bin/blocklistd.conf.5

.\" $NetBSD: blocklistd.conf.5,v 1.7 2025/02/11 17:47:05 christos Exp $
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.\" by Christos Zoulas.
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.Dd February 5, 2025
.Dt BLOCKLISTD.CONF 5
.Os
.Sh NAME
.Nm blocklistd.conf
.Nd configuration file format for blocklistd
.Sh DESCRIPTION
The
.Nm
file contains configuration entries for
.Xr blocklistd 8
in a fashion similar to
.Xr inetd.conf 5 .
Only one entry per line is permitted.
Every entry must have all fields populated.
Each field can be separated by a tab or a space.
Comments are denoted by a
.Dq #
at the beginning of a line.
.Pp
There are two kinds of configuration lines,
.Va [local]
and
.Va [remote] .
By default, configuration lines are
.Va [local] ,
i.e. the address specified refers to the addresses on the local machine.
To switch to between
.Va [local]
and
.Va [remote]
configuration lines you can specify the stanzas:
.Dq [local]
and
.Dq [remote] .
.Pp
On
.Va [local]
and
.Va [remote]
lines
.Dq *
means use the default, or wildcard match.
In addition, for
.Va [remote]
lines
.Dq =
means use the values from the matched
.Va [local]
configuration line.
.Pp
The first four fields,
.Va location ,
.Va type ,
.Va proto ,
and
.Va owner
are used to match the
.Va [local]
or
.Va [remote]
addresses, whereas the last 3 fields
.Va name ,
.Va nfail ,
and
.Va disable
are used to modify the filtering action.
.Pp
The first field denotes the
.Va location
as an address, mask, and port.
The syntax for the
.Va location
is:
.Bd -literal -offset indent
	[<address>|<interface>][/<mask>][:<port>]
.Ed
.Pp
The
.Dv address
can be an IPv4 address in numeric format, an IPv6 address
in numeric format and enclosed by square brackets, or an interface name.
Mask modifiers are not allowed on interfaces because interfaces
can have multiple addresses in different protocols where the mask has a
different size.
.Pp
The
.Dv mask
is always numeric, but the
.Dv port
can be either numeric or symbolic.
.Pp
The second field is the socket
.Va type :
.Dv stream ,
.Dv dgram ,
or numeric.
The third field is the
.Va protocol :
.Dv tcp ,
.Dv udp ,
.Dv tcp6 ,
.Dv udp6 ,
or numeric.
The fourth field is the effective user
.Va ( owner )
of the daemon process reporting the event,
either as a username or a userid.
.Pp
The rest of the fields control the behavior of the filter.
.Pp
The
.Va name
field, is the name of the packet filter rule to be used.
If the
.Va name
starts with a hyphen
.Pq Dq - ,
then the default rulename is prepended to the given name.
If the
.Dv name
contains a
.Dq / ,
the remaining portion of the name is interpreted as the mask to be
applied to the address specified in the rule, causing a single rule violation to
block the entire subnet for the configured prefix.
.Pp
The
.Va nfail
field contains the number of failed attempts before access is blocked,
defaulting to
.Dq *
meaning never, and the last field
.Va duration
specifies the amount of time since the last access that the blocking
rule should be active, defaulting to
.Dq *
meaning forever.
The default unit for
.Va duration
is seconds, but one can specify suffixes for different units, such as
.Dq m
for minutes
.Dq h
for hours and
.Dq d
for days.
.Pp
Matching is done first by checking the
.Va [local]
rules individually, in the order of the most specific to the least specific.
If a match is found, then the matching
.Va [remote]
rules are applied.
The
.Va name ,
.Va nfail ,
and
.Va duration
fields can be altered by the
.Va [remote]
rule that matched.
.Pp
The
.Va [remote]
rules can be used for allowing specific addresses, changing the mask
size (via
.Va name ) ,
the rule that the packet filter uses (also via
.Va name ) ,
the number of failed attempts (via
.Va nfail ) ,
or the duration to block (via
.Va duration ) .
.Sh FILES
.Bl -tag -width /etc/blocklistd.conf -compact
.It Pa /etc/blocklistd.conf
Configuration file.
.El
.Sh EXAMPLES
.Bd -literal -offset 8n
# Block ssh, after 3 attempts for 6 hours on the bnx0 interface
[local]
# location	type	proto	owner	name	nfail	duration
bnx0:ssh	*	*	*	*	3	6h
[remote]
# Never block 1.2.3.4
1.2.3.4:ssh	*	*	*	*	*	*
# Never block the example IPv6 subnet either
[2001:db8::]/32:ssh	*	*	*	*	*	*
# For addresses coming from 8.8.0.0/16 block whole /24 networks instead
# individual hosts, but keep the rest of the blocking parameters the same.
8.8.0.0/16:ssh	*	*	*	/24	=	=
.Ed
.Sh SEE ALSO
.Xr blocklistctl 8 ,
.Xr blocklistd 8
.Sh HISTORY
.Nm
first appeared in
.Nx 7 .
.Fx
support for
.Nm
was implemented in
.Fx 11 .
.Sh AUTHORS
.An Christos Zoulas