How to deal with this:
nc: Proxy error: "HTTP/1.1 407 Proxy Authentication Required"
nc
has a -P
option for proxy username, but what's for password?
It's not clear what Netcat variant you're using, but presuming it's OpenBSD's netcat, the proxy authentication behavior, as of version 1.105, should have you prompted on the commandline for a password:
"Proxy password for %s@%s: "
is the prompt, with proxy username & proxy password applied for the string format inputs.