Brutus is one of the fastest, most flexible remote password crackers you can get your hands on - it's also free. It is available for Windows 9x, NT and 2000, there is no UN*X version available although it is a possibility at some point in the future. This Windows-only cracker bangs against network services of remote systems trying to guess passwords by using a dictionary and permutations thereof. It supports HTTP, POP3, FTP, SMB, TELNET, IMAP, NTP, and more.
This tool allows for rapid dictionary attacks against network login systems, including FTP, POP3, IMAP, Netbios, Telnet, HTTP Auth, LDAP NNTP, VNC, ICQ, Socks5, PCNFS, and more. It includes SSL support and is apparently now part of Nessus.
TSGrinder is the first production Terminal
Server brute force tool. The main idea here is that the Administrator account,
since it cannot be locked out for local logons, can be brute forced. And having
an encrypted channel to the TS logon process sure helps to keep IDS from
catching the attempts. It is a "dictionary" based attack tool, but it does have
some interesting features like "l337" conversion, and supports multiple attack
windows from a single dictionary file. It supports multiple password attempts
in the same connection, and allows you to specify how many times to try a
username/password combination within a particular connection.