Can I pipe/redirect a console application through netcat so it can be used remotely?

Is it possible to 'pipe' an instance of a console application through netcat, so netcat is listening for a new connection and redirects the stdin and stdout over the network connection.

Solution 1:

Well, as documented in Wikipedia and netcat documentation, there is a -e option that causes it to spawn (execute) a program upon receipt of a connection, attaching the socket to stdin, stdout, and stderr of the process.  Example usage:

nc -l -pport_number-eprogram_name

Examples commonly show /bin/sh or bash being used as the program_name.  Use of this option is discouraged because it basically opens an anonymous, passwordless access portal into your machine.  Of course, this is mitigated by using a program with less power than the shell (one that doesn’t have the ability to escape to a shell), minimizing your use of it, and keeping it a secret.  Nonetheless, the original developers of netcat felt strongly enough that this option was a bad idea that they disabled it by default, and conditioned it under the “GAPING_SECURITY_HOLE” compilation option.  This is mentioned briefly in this NetCat Tutorial and other netcat documentation.

A Google search led me to discussions of this issue on other Stack Exchange sites: Stack Overflow and Server Fault.  Multiple contributors offered the following technique to do the same thing without using the -e option (i.e., in a version of netcat that has the -e option disabled):

On the server:
mkfifopipe_name
nc -l -pport_number<pipe_name  | program_name>pipe_name

On the client:
nc server_machine_name port_number

A couple of notes:

• On some versions of netcat, -l implies -p, so you should say just -l and then the port number.
• You might want to wrap your solution in a while true loop.