pcap_lookupdev undefined

Question

I am developing for OSX 10.8. I just installed libpcap via MacPorts and tried running a simple device hunter (below)

#include <stdio.h>
#include <pcap.h>

int main(int argc,char *argv[])
{
    char *dev, errbuf[PCAP_ERRBUF_SIZE];

    dev = pcap_lookupdev(errbuf);
    if(dev == NULL)
    {
        fprintf(stderr, "Couldn't find default device: %s\n", errbuf);
        return(2);
    }

    printf("Device %s\n", dev);
    return(0);
}

and while trying to compile with g++ i am getting:

    Undefined symbols for architecture x86_64:
  "_pcap_lookupdev", referenced from:
      _main in ccIMp1m2.o

Any helpful advice so I can actually get started with learning this stuff would be great! I googled for a solid 10-15 minutes but just couldn't find much on my particular issue with my setup.

Answer 1

You need to link libpcap. Probably -lpcap added to your compiler command line will work. If it's installed somewhere strange (and it might be, since you got it from MacPorts), you might need -L/path/to/libpcap -lpcap.