Both Fink and Nmap have problems compiling with earlier versions of Xcode. Xcode is found here. The error I got with Fink was:
./pcap-bpf.c: In function 'pcap_inject_bpf':./pcap-bpf.c:348: error: 'BIOCSHDRCMPLT' undeclared (first use in this function)./pcap-bpf.c:348: error: (Each undeclared identifier is reported only once./pcap-bpf.c:348: error: for each function it appears in.)make: *** [pcap-bpf.o] Error 1make: *** [libpcap/libpcap.a] Error 2
Upgrading to xcode 2.2.1 fixed both of these problems.