Iterate over a file.
For each line in the file:
    If the line starts with #, go on to the next line
    If the line contains anything but letters, numbers, and two : characters, report an error and exit
    Remove whitespace from the start and end of the line
    Split the line up, using : as the separator
    Print out 'user "remote-username" with password "password" is "local-username" here'
    Go on to the next line