undefined reference to `libnet_name2addr4'

I was getting the following error on Debian Squeeze while compiling the MS Windows Malformed IP Options DoS Exploit (MS05-019):

"> : undefined reference to `libnet_name2addr4'
> : undefined reference to `libnet_addr2name4'
> : undefined reference to `libnet_get_prand'
> : undefined reference to `libnet_getdevice'
> : undefined reference to `libnet_get_ipaddr4'
> : undefined reference to `libnet_get_hwaddr'
> : undefined reference to `libnet_init'
> : undefined reference to `libnet_build_udp'
> : undefined reference to `libnet_build_ipv4'
> : undefined reference to `libnet_build_ethernet'
> : undefined reference to `libnet_write'
> : undefined reference to `libnet_geterror'
> : undefined reference to `libnet_destroy'

"
The fix was to add -lnet to gcc command:

gcc -lnet 942.c

http://www.securityfocus.com/archive/89/390587/30/30/threaded