Command Section
MAC_IFOFF(4)           FreeBSD Kernel Interfaces Manual           MAC_IFOFF(4)

     mac_ifoff - interface silencing policy

     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):


     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.

     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),

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

     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.

     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.

FreeBSD 11.1-RELEASE-p4          July 25, 2015         FreeBSD 11.1-RELEASE-p4
Command Section