Request for authentication in a password-protected Redis server.
Redis can be instructed to require a password before allowing clients to execute
commands.
This is done using the requirepass directive in the configuration file.
If password matches the password in the configuration file, the server replies
with the OK status code and starts accepting commands.
Otherwise, an error is returned and the clients needs to try a new password.
Note: because of the high performance nature of Redis, it is possible to try a lot of passwords in parallel in very short time, so make sure to generate a strong and very long password so that this attack is infeasible.