trouble with perl, libnet and CPAN on cygwin

[Steve Kelem]

I'm trying to install the latest libnet for perl on cygwin 1.0.
I get the following messages:

/usr/local/bin/perl -I/usr/local/lib/perl5/5.6.0/cygwin
-I/usr/local/lib/perl5/5.6.0 /usr/local/lib/perl5/5.6.0/ExtUtils/xsubpp
-typemap /usr/local/lib/perl5/5.6.0/ExtUtils/typemap -typemap typemap
MD2.xs > MD2.xsc && mv MD2.xsc MD2.c
gcc -c  -fno-strict-aliasing -I/usr/local/include -DUSEIMPORTLIB -O
-DVERSION=\"1.00\" -DXS_VERSION=\"1.00\"
-I/usr/local/lib/perl5/5.6.0/cygwin/CORE  MD2.c
In file included from MD2.xs:36:
/usr/local/lib/perl5/5.6.0/cygwin/CORE/perl.h:3185: sys/ipc.h: No such
file or directory
/usr/local/lib/perl5/5.6.0/cygwin/CORE/perl.h:3186: sys/sem.h: No such
file or directory

Any idea where these files are supposed to come from or what a
workaround is?

Thanks for your help,
Steve Kelem