.\" Copyright (c) 2002 Networks Associates Technology, Inc.
.\" All rights reserved.
.\"
.\" This software was developed for the FreeBSD Project by Chris Costello
.\" at Safeport Network Services and Network Associates Laboratories, the
.\" Security Research Division of Network Associates, Inc. under
.\" DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
.\" DARPA CHATS research program.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: head/share/man/man4/mac_ifoff.4 285873 2015-07-25 15:56:49Z trasz $
.\"
.Dd July 25, 2015
.Dt MAC_IFOFF 4
.Os
.Sh NAME
.Nm mac_ifoff
.Nd "interface silencing policy"
.Sh SYNOPSIS
To compile the interface silencing policy into your kernel,
place the following lines in your kernel
configuration file:
.Bd -ragged -offset indent
.Cd "options MAC"
.Cd "options MAC_IFOFF"
.Ed
.Pp
Alternately, to load the interface silencing policy module at boot time,
place the following line in your kernel configuration file:
.Bd -ragged -offset indent
.Cd "options MAC"
.Ed
.Pp
and in
.Xr loader.conf 5 :
.Bd -literal -offset indent
mac_ifoff_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
interface silencing module allows administrators to enable and disable
incoming and outgoing data flow on system network interfaces
via the
.Xr sysctl 8
interface.
.Pp
To disable network traffic over the loopback
.Pq Xr lo 4
interface, set the
.Xr sysctl 8
OID
.Va security.mac.ifoff.lo_enabled
to 0 (default 1).
.Pp
To enable network traffic over other interfaces,
set the
.Xr sysctl 8
OID
.Va security.mac.ifoff.other_enabled
to 1 (default 0).
.Pp
To allow BPF traffic to be received,
even while other traffic is disabled,
set the
.Xr sysctl 8
OID
.Va security.mac.ifoff.bpfrecv_enabled
to 1 (default 0).
.Ss Label Format
No labels are defined.
.Sh SEE ALSO
.Xr mac 4 ,
.Xr mac_bsdextended 4 ,
.Xr mac_lomac 4 ,
.Xr mac_mls 4 ,
.Xr mac_none 4 ,
.Xr mac_partition 4 ,
.Xr mac_portacl 4 ,
.Xr mac_seeotheruids 4 ,
.Xr mac_test 4 ,
.Xr mac 9
.Sh HISTORY
The
.Nm
policy module first appeared in
.Fx 5.0
and was developed by the
.Tn TrustedBSD
Project.
.Sh AUTHORS
This software was contributed to the
.Fx
Project by Network Associates Labs,
the Security Research Division of Network Associates
Inc.
under DARPA/SPAWAR contract N66001-01-C-8035
.Pq Dq CBOSS ,
as part of the DARPA CHATS research program.
.Sh BUGS
While the MAC Framework design is intended to support the containment of
the root user, not all attack channels are currently protected by entry
point checks.
As such, MAC Framework policies should not be relied on, in isolation,
to protect against a malicious privileged user.