The protocol that commonly uses Port 21 for its default communication is FTP (File Transfer Protocol).
The version of Internet Information Services (IIS) commonly associated with Windows Server 2003 and Windows XP Professional is IIS 6.
The port number typically used for the server mode in HSQLDB is 9001.
The DES algorithm employs 16 cycles of 48-bit subkeys.
The programming language commonly associated with the vulnerability "Incorrect Element Removal" is PHP.