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NAME
     enc - Encapsulating Interface


SYNOPSIS
     To compile this driver into the kernel, place the following line in your
     kernel configuration file:

           device enc


DESCRIPTION
     The enc interface is a software loopback mechanism that allows hosts or
     firewalls to filter ipsec(4) traffic using any firewall package that
     hooks in via the pfil(9) framework.

     The enc interface allows an administrator to see outgoing packets before
     they have been processed by ipsec(4), or incoming packets after they have
     been similarly processed, via tcpdump(1).

     The “enc0” interface inherits all IPsec traffic.  Thus all IPsec traffic
     can be filtered based on “enc0”, and all IPsec traffic could be seen by
     invoking tcpdump(1) 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:

           tcpdump -i enc0


SEE ALSO
     tcpdump(1), bpf(4), ipf(4), ipfw(4), ipsec(4), pf(4), tcpdump(8)