freebsd security - Feb 2011 - nessus would not compile under 8.1

hi gurus:

tried to install nessus and it would not compile:

===>  Configuring for nessus-libraries-2.2.9_1
********************************************************
*                   W a r n i n g                      *
*                                                      *
* Nessus needs Berkeley Packet Filter (bpf).           *
* To use nessus, your kernel must be rebuilt with bpf, *
* and make bpf devices on /dev directory.              *
*                                                      *
* Be sure to build as many bpf devices as you need.    *
* For more info on this read files/README.BPF          *
********************************************************
*** Error code 1

Stop in /usr/ports/security/nessus-libraries.
*** Error code 1

Stop in /usr/ports/security/nessus-libnasl.
*** Error code 1

my bpf is enabled in kernel:

user@host:/usr/ports/security/nessus:$ ls -al /dev/bpf*
crw-------  1 root  wheel    0,  24 Feb 18 12:36 /dev/bpf
lrwxr-xr-x  1 root  wheel         3 Feb 18 12:36 /dev/bpf0 -> bpf

and i could not find this README>BPF:

user@host:/usr/ports/security/nessus:$ more files/README.BPF
files/README.BPF: No such file or directory

my tcpdump and tshark work fine so it should not be bpf issue. any ideas?

thanks