ENC(4)                    OpenBSD Programmer's Manual                   ENC(4)

NAME
     enc - Encapsulating Interface

SYNOPSIS
     pseudo-device enc 4

DESCRIPTION
     The enc interface is a software loopback mechanism that allows hosts or
     firewalls to filter ipsec(4) traffic using pf(4). The vpn(8) manpage
     shows an example of such a setup.

     The enc interface is a software loopback mechanism that allows an admin-
     istrator to see outgoing packets before they have been processed by
     ipsec(4), or incoming packets after they have been similarly processed,
     via tcpdump(8).

     The ``enc0'' interface inherits all IPsec traffic.  Thus all IPsec traf-
     fic can be filtered based on ``enc0'', and all IPsec traffic could be
     seen by invoking tcpdump(8) on the ``enc0'' interface.

EXAMPLES
     To see all outgoing packets before they have been processed via ipsec(4),
     or all incoming packets after they have been similarly processed:

     #> ifconfig enc0 up
     #> tcpdump -i enc0

SEE ALSO
     bpf(4), inet(4), ipsec(4), netintro(4), pf(4), tcpdump(8), vpn(8)

OpenBSD 3.0                     October 7, 1999                              1
