NAME

     mac_ifoff — interface silencing policy

SYNOPSIS

     To compile the interface silencing policy into your kernel, place the following lines in
     your kernel configuration file:

           options MAC
           options MAC_IFOFF

     Alternately, to load the interface silencing policy module at boot time, place the following
     line in your kernel configuration file:

           options MAC

     and in loader.conf(5):

           mac_ifoff_load="YES"

DESCRIPTION

     The mac_ifoff interface silencing module allows administrators to enable and disable
     incoming and outgoing data flow on system network interfaces via the sysctl(8) interface.

     To disable network traffic over the loopback (lo(4)) interface, set the sysctl(8) OID
     security.mac.ifoff.lo_enabled to 0 (default 1).

     To enable network traffic over other interfaces, set the sysctl(8) OID
     security.mac.ifoff.other_enabled to 1 (default 0).

     To allow BPF traffic to be received, even while other traffic is disabled, set the sysctl(8)
     OID security.mac.ifoff.bpfrecv_enabled to 1 (default 0).

   Label Format
     No labels are defined.

SEE ALSO

     mac(4), mac_bsdextended(4), mac_lomac(4), mac_mls(4), mac_none(4), mac_partition(4),
     mac_portacl(4), mac_seeotheruids(4), mac_test(4), mac(9)

HISTORY

     The mac_ifoff policy module first appeared in FreeBSD 5.0 and was developed by the
     TrustedBSD Project.

AUTHORS

     This software was contributed to the FreeBSD Project by Network Associates Labs, 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.

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.