Just adding some additional information from my own tests in case anyone comes here looking for more details:
- the
USERcommand does not seem to be required for Twitch IRC; sending it seems to have no effect - anonymous connections don’t seem to work with an empty string for a password, but just using a random string seems to work
- there doesn’t seem to be a length requirement for the numeric nickname suffix, I’ve successfully tried with 20 numbers
To recap, this seems to be the syntax:
PASS <random_string>
NICK justinfan<random_number>