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MAC_IFOFF(4)             BSD 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 dis-
     abled, 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 devel-
     oped by the TrustedBSD Project.

     This software was contributed to the FreeBSD Project by Network Asso-
     ciates 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.

     See mac(9) concerning appropriateness for production use.  The TrustedBSD
     MAC Framework is considered experimental in FreeBSD.

     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.

BSD                            December 10, 2002                           BSD