In the situations where nc is useful then scapy is probably not an option. Nc, dd, and a few others are almost always present and great when you are in a real bind... something went wrong in a network install in pxelinux, and you want to copy off dumps or config files, or copy on a missing file. Otherwise, there are better ways to do most of the things mentioned in the article, most involving scp.
EDIT: the number of responses to this article happily highlighting the lack of security in netcat just terrifies me.
EDIT2: Ah, I see what you were saying (and scapy is an awfully cool library). It was just a convenient place for me to highlight was I didn't think was highlighted enough in the article: nc can do neat things, but not much that can't be accomplished better with other tools - its big advantage is that it's almost always present, even if ssh/scp, rsync, netstat, wget/curl, etc are not. Like using cat + sed as a text editor :)
I know they are different tools, I meant if you like to play with ncat, tcpdump etc and/or you're learning netsec you may want to play with scapy. Directed to the very few readers that may know about nc and not scapy :-)
EDIT: the number of responses to this article happily highlighting the lack of security in netcat just terrifies me.
EDIT2: Ah, I see what you were saying (and scapy is an awfully cool library). It was just a convenient place for me to highlight was I didn't think was highlighted enough in the article: nc can do neat things, but not much that can't be accomplished better with other tools - its big advantage is that it's almost always present, even if ssh/scp, rsync, netstat, wget/curl, etc are not. Like using cat + sed as a text editor :)