John the Ripper
About
John the Ripper is designed to be both feature-rich and fast. It combines several cracking modes in one program and is fully configurable for your particular needs (you can even define a custom cracking mode using the built-in compiler supporting a subset of C). Also, John is available for several different platforms which enables you to use the same cracker everywhere (you can even continue a cracking session which you started on another platform).
Out of the box, John supports (and autodetects) the following Unix crypt(3) hash types: traditional DES-based, “bigcrypt”, BSDI extended DES-based, FreeBSD MD5-based (also used on Linux and in Cisco IOS), and OpenBSD Blowfish-based (now also used on some Linux distributions and supported by recent versions of Solaris). Also supported out of the box are Kerberos/AFS and Windows LM (DES-based) hashes, as well as DES-based tripcodes.
When running on Linux distributions with glibc 2.7+, John 1.7.6+ additionally supports (and autodetects) SHA-crypt hashes (which are actually used by recent versions of Fedora and Ubuntu), with optional OpenMP parallelization (requires GCC 4.2+, needs to be explicitly enabled at compile-time by uncommenting the proper OMPFLAGS line near the beginning of the Makefile).
Similarly, when running on recent versions of Solaris, John 1.7.6+ supports and autodetects SHA-crypt and SunMD5 hashes, also with optional OpenMP parallelization (requires GCC 4.2+ or recent Sun Studio, needs to be explicitly enabled at compile-time by uncommenting the proper OMPFLAGS line near the beginning of the Makefile and at runtime by setting the OMP_NUM_THREADS environment variable to the desired number of threads).
John the Ripper Pro adds support for Windows NTLM (MD4-based) and Mac OS X 10.4+ salted SHA-1 hashes.
“Community enhanced” -jumbo versions add support for many more password hash types, including Windows NTLM (MD4-based), Mac OS X 10.4-10.6 salted SHA-1 hashes, Mac OS X 10.7 salted SHA-512 hashes, raw MD5 and SHA-1, arbitrary MD5-based “web application” password hash types, hashes used by SQL database servers (MySQL, MS SQL, Oracle) and by some LDAP servers, several hash types used on OpenVMS, password hashes of the Eggdrop IRC bot, and lots of other hash types, as well as many non-hashes such as OpenSSH private keys, S/Key skeykeys files, Kerberos TGTs, PDF files, ZIP (classic PKZIP and WinZip/AES) and RAR archives.
Unlike older crackers, John normally does not use a crypt(3)-style routine. Instead, it has its own highly optimized modules for different hash types and processor architectures. Some of the algorithms used, such as bitslice DES, couldn’t have been implemented within the crypt(3) API; they require a more powerful interface such as the one used in John. Additionally, there are assembly language routines for several processor architectures, most importantly for x86-64 and x86 with SSE2.