Poor Man's FTP

In the November issue of Linux Journal Magazine, Kyle Rankin wrote an article about his experience attending the DEF CON conference.  One lesson he took away was the importance of knowing how to use the basic Linux commands, such as vi and sh.  Being familiar with these commands means that you won't be dead in the water if you have to work on a computer with a minimal Linux install.

One of these commands is netcat (nc).  Netcat allows you to open TCP and UDP connections with other computers as well as listen for connections.  Kyle described many interesting ways that you can use this command.  My favorite was using it to transfer files.  I think that this technique would come in very handily if ssh or ftp is not installed.

It's very simple.  The computer receiving the file runs this command:

nc -l 31337 > output_file

And then the computer sending the file runs this command:

nc hostname 31337 < input_file

This will send the file through port 31337 and automatically close the connection when the transfer is complete.  It doesn't matter what port you use, so long as the port isn't being used by another program.