how to compile libpcap with bison/flex

[ashadul hoque]

Hi everybody,

I am using 5.2.1-RELEASE. When installing ngrep-lib from ports collection 
it tells me that i need to compile libpcap with bison/flex.

I installed libpcap source. I have complied sources before but always with 
default options. I read the Makefile and found no pointers. I googled and 
found nothing that helps me.

Ho do i proceed?

Thanks in advance.

regards
Ashadul