1.\" $OpenBSD: enc.4,v 1.14 2001/06/26 23:24:11 angelos Exp $ 2.\" 3.Dd October 7, 1999 4.Dt ENC 4 5.Os 6.Sh NAME 7.Nm enc 8.Nd Encapsulating Interface 9.Sh SYNOPSIS 10.Cd "pseudo-device enc 4" 11.Sh DESCRIPTION 12The 13.Nm 14interface is a software loopback mechanism that allows hosts or 15firewalls to filter 16.Xr ipsec 4 17traffic using 18.Xr pf 4 . 19The 20.Xr vpn 8 21manpage shows an example of such a setup. 22.Pp 23The 24.Nm 25interface is a software loopback mechanism that allows an administrator 26to see outgoing packets before they have been processed by 27.Xr ipsec 4 , 28or incoming packets after they have been similarly processed, via 29.Xr tcpdump 8 . 30.Pp 31The 32.Dq enc0 33interface inherits all IPsec traffic. 34Thus all IPsec traffic can be filtered based on 35.Dq enc0 , 36and all IPsec traffic could be seen by invoking 37.Xr tcpdump 8 38on the 39.Dq enc0 40interface. 41.Sh EXAMPLES 42To see all outgoing packets before they have been processed via 43.Xr ipsec 4 , 44or all incoming packets after they have been similarly processed: 45.Bd -literal 46#> ifconfig enc0 up 47#> tcpdump -i enc0 48.Ed 49.Sh SEE ALSO 50.Xr bpf 4 , 51.Xr inet 4 , 52.Xr ipsec 4 , 53.Xr netintro 4 , 54.Xr pf 4 , 55.Xr tcpdump 8 , 56.Xr vpn 8 57