3.8.3.24 -proxycmd: specify a local proxy command
This option enables PuTTY's mode for running a command on the local machine and using it as a proxy for the network connection. It expects a shell command string as an argument.
See section 4.15.1 for more information on this, and on other proxy settings. In particular, note that since the special sequences described there are understood in the argument string, literal backslashes must be doubled (if you want \ in your command, you must put \\ on the command line).