Comparison of operating system kernels

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A kernel (called nucleus or hardcore by some operating systems) is the core component of every computer operating system. While kernels are highly technical in nature, and may be hidden from the user under many layers of software and applications, they do have distinguishing or characteristic features, such as computer architecture, design goals, as well as the more practical features that they provide. A direct comparison of operating system kernels can highlight these design choices, and provide insight into different niches and the evolving technology of kernels.

Comparison criterion[edit]

The following tables compare general and technical information for a number of widely used and currently available operating system kernels. Please see the individual products' articles for further information.

Even though there is a large number and variety of available Linux distributions, all of these kernels are grouped under a single entry in these tables, due to differences being of the patch level. See comparison of Linux distributions for a detailed comparison. Linux distributions that have highly modified kernels, for example Real-time computing kernels, should be listed separately. There are also a wide variety of minor BSD operating systems, many of which can be found at comparison of BSD operating systems.

The tables specifically do not include subjective viewpoints on the merits of each kernel or operating system. For this kind of information, please see operating system advocacy.

Feature overview[edit]

The major contemporary general-purpose kernels are shown in comparison. Only an overview of the technical features is detailed.

Kernel name Used in Creator Executable
format
(also see
section
below)
Type Integrated firewall SMP support Multiple architecture
support
(also see
section below).
Multitasking Virtualization Security Profiling/Debugging Soft real-time support Hard real-time support Can keep RTC in UT[1]
Agnix [3] ? ? ? ? ? ? ? Yes ? ? ? ? ? ?
Amiga Exec AmigaOS Commodore International HUNK Exokernel (atypical)[2] No No No Yes No No Yes No No No
Amiga Exec SG (2nd Generation) AmigaOS 4 Hyperion Entertainment ELF/HUNK Exokernel (atypical) No No No Yes No No Yes No No ?
DragonFly BSD kernel DragonFly BSD Matt Dillon ELF, others - platform dependent hybrid IPFilter, Ipfirewall,
PF
Yes Yes Yes chroot, jail, vkernel Unix permissions DDB, KGDB ? ? ?
FreeBSD kernel FreeBSD,

Debian GNU/kFreeBSD, Gentoo/FreeBSD, Orbis OS

The FreeBSD Project ELF, others - platform dependent monolithic IPFilter, Ipfirewall,
PF
Yes Yes Yes chroot, jail, bhyve Unix permissions, POSIX.1e and NFSv4 ACLs,[3] Capsicum, TrustedBSD MAC, OpenBSM KDB, DDB, KGDB, DTrace, hwpmc Yes ? Yes
GNU Hurd [4] GNU/Hurd (Arch Hurd, Debian GNU/Hurd, NixOS[4]) GNU Project/Free Software Foundation ELF multiserver microkernel No partial No Yes chroot, Xen Unix permissions, POSIX ACL, POSIX Capabilities ? ? ? ?
GNU Mach [5] part of GNU Hurd, used in GNU/Hurd GNU Project/Free Software Foundation ELF microkernel No partial No Yes chroot, Xen Unix permissions, POSIX ACL, POSIX Capabilities ? ? ? ?
Inferno kernel Inferno Bell Labs / Vita Nuova Holdings ? virtual machine ? Yes Yes Yes chroot, Xen ? ? ? ? ?
L4 L4 Jochen Liedtke No microkernel No Yes Yes Yes Yes Afterburner/L4 [6], Marzipan [7], capabilities in L4/Fiasco[5] L4/Fiasco[5] L4/Fiasco[5] ? ?
Linux kernel [8] Linux, Android, webOS, Firefox OS, Chrome OS, Syllable Server, Mastodon Linux, OpenBSD/Linux, Plan 9/Linux, Sailfish OS, Tizen, others Linus Torvalds ELF, others monolithic *ipfwadm (2.0 –) Yes Yes Yes cgroups, chroot, Lguest, Xen, KVM, kvm-lite, LXC Unix permissions, POSIX ACL, POSIX Capabilities, keyctl, LSM(SELinux, SMACK, TOMOYO Linux, AppArmor) OProfile, kprobe, SystemTap, JProbe, ftrace, KDB, KGDB, kernel marker, perf tools CONFIG_PREEMPT (CONFIG_PREEMPT_RT Patch) Yes
Compute Node Linux Compute Node Linux Cray Inc. ? ? ? ? ? ? ? ? ? ? ? ?
Mach [9] NeXTSTEP and OPENSTEP for Mach Carnegie Mellon University Mach-O microkernel ? ? ? ? ? ? ? ? ? ?
MINIX 3 kernel [10] MINIX 3 Andrew S. Tanenbaum ELF,[6] a.out[7][8] microkernel No No No Yes No Unix permissions Call profiling, statistical profiling, Minix Debugger (mdb) No No ?
MkLinux [11] ? OSF Research Institute and Apple Computer ? microkernel ? ? ? ? ? ? ? ? ? ?
NetBSD kernel NetBSD,

GNU/kNetBSD (Debian GNU/NetBSD),

The NetBSD Project ELF, others - platform dependent monolithic, any kernel using RUMP architecture IPFilter, PF, NPF Yes Yes Yes Xen, chroot kauth, Unix permissions DDB[disambiguation needed], KGDB, tprof POSIX real-time scheduling extensions Kernel preemption [9] ?
NetWare kernel NetWare Novell NLM hybrid Yes Yes No Yes ? ? ? ? ? ?
OpenBSD kernel OpenBSD OpenBSD developers ELF, others - platform dependent monolithic PF Yes Yes Yes ? Unix permissions ? ? ? ?
OS/2 kernel OS/2 version 2 and above IBM LX hybrid No Yes No PowerPC version developed but never officially released. Yes No Yes Yes Yes No ?
Plan 9 kernel Plan 9 from Bell Labs Bell Labs ? hybrid ipmux Yes Yes Yes ? ? ? ? ? ?
ReactOS kernel ReactOS ReactOS Foundation PE, others? hybrid ? ? ? Yes ? ? ? ? ? ?
Rockbox kernel Rockbox The Rockbox Project ? ? ? ? Yes ? ? ? ? ? ? ?
SunOS kernel SunOS Sun Microsystems a.out
monolithic ? Yes Yes Yes ? Unix permissions ? ? ? ?
Solaris kernel Solaris,

OpenSolaris, GNU/kOpenSolaris (Nexenta OS)

Sun Microsystems ELF (32-bit only until
Solaris 7 in 1998)
monolithic IPFilter Yes Yes Yes Zones, chroot Unix permissions, ACL, RBAC, Auditing, Privileges, Zones, Trusted Extensions DTrace, CPU profiling, microstate accounting, perf counters, kernel lock stats, kstats, mdb, kmdb Real-time scheduler ? ?
Trix kernel Trix, GNU/kTrix Massachusetts Institute of Technology a.out monolithic ? Yes No Yes ? ? ? ? ? ?
Windows NT kernel [12] Windows NT, 2000,
XP, 2003, Vista, Windows 7, Windows 8
Microsoft PE, others? hybrid Yes Yes Yes Yes Hyper-V ACL Event Tracing[10] No No Unofficial[11]
XNU (Darwin kernel) [13] Mac OS X, iOS,

OpenDarwin, PureDarwin GNU/Darwin

Apple Computer Mach-O hybrid Ipfirewall,
PF (starting in Lion)
Yes Yes Yes ? Unix permissions, ACL DTrace ? ? ?
SPARTAN kernel [14] HelenOS Jakub Jermar ELF microkernel ? Yes Yes Yes ? ? ? ? ? ?
Kernel name Used in Creator Executable
format
(also see
section
below)
Type Integrated firewall SMP support Multiple architecture
support
(also see
section below).
Multitasking Virtualization Security Profiling/Debugging Soft real-time support Hard real-time support Can keep RTC in UT

Transport protocol support[edit]

Kernel Name TCP UDP SCTP DCCP
FreeBSD kernel Yes Yes Yes No
Linux kernel Yes Yes Yes Yes
Solaris kernel Yes Yes Yes ?
Windows NT kernel Yes Yes No ?
XNU Yes Yes No No

In-kernel security[edit]

Kernel Name File access control Disable memory execution support Kernel ASLR Mandatory access control Capability-based security In-kernel key management Audit API Sandbox SYN flood protection UDP flood protection Ping flood protection Smurf attack protection Network Behavior Analysis
Linux Traditional Unix permissions, POSIX ACL Yes Yes LSM(SELinux, SMACK, TOMOYO Linux, AppArmor) No keyctl fanotify SELinux Sandbox, seccomp, KVM SYN cookies No? No? No? No
FreeBSD Kernel Traditional Unix permissions, POSIX and NFSv4 ACL Yes ? TrustedBSD MAC Capsicum ? OpenBSM Capsicum SYN cookies ? ? ? ?
Solaris Kernel Traditional Unix permissions, POSIX ACL, NFSv4 ACL Default ? Solaris Trusted Extensions ? ? ? ? ? ? ? ? ?
Windows NT kernel Access control list DEP Yes Mandatory Integrity Control ? ? ? ? ? ? ? ? ?
XNU Traditional Unix permissions, access control list Yes Yes TrustedBSD MAC ? ? OpenBSM Apple XNU Sandbox ? ? ? ? ?

In-kernel virtualization[edit]

Kernel Name Container (no resource management, no security) Container (no resource management) Container (resource management) Paravirtualization Full virtualization User-space execution
Linux chroot LXC Virtio, Hyper-V (guest only), Xen (guest only), VMI (guest only), kvm-lite, lguest KVM UML
FreeBSD kernel chroot jail Virtio, Xen (guest only) BHyVe (KVM) ?
Solaris kernel chroot Solaris Containers / Zones No No No
Windows NT kernel AppContainers AppContainers AppContainers Hyper-V Hyper-V ?
XNU chroot ? ? ? ? ?

In-kernel server support[edit]

Kernel Name HTTP FTP NFS CIFS Name server Transport-layer load balancer Application-layer load balancer 9P SSL proxy
Linux kernel (TUX web server patch) (TUX web server patch) knfsd No ? IP Virtual Server (KTCPVS) (patch available) No
FreeBSD kernel No No Yes No No Yes No No No
Solaris kernel ? ? Yes Yes[12] ? Yes[13] Yes[13] ? KSSL
Windows NT kernel HTTP.sys ? ? Yes ? Yes Yes No ?
XNU No No Yes No No No No No No

Binary format support[edit]

A comparison of OS support for different binary formats (executables):

Kernel Name a.out ECOFF ELF FDPIC
ELF
binaries
(mmu less)
flat
binaries
(superH)
HUNK Mach-O Misc
(wrapper
based,
like
interpreters)
PE SOM
(PA-RISC,
HP-UX)
NLM PEF DOS COM MZ LE LX NE
Amiga Exec No No Yes[14] No No Yes No No No No ? ? ? ? ? ? ?
HP-UX kernel No No Yes No No No No No No Yes No No ? ? ? ? ?
Linux kernel Yes Yes Yes Yes Yes No No Yes Some[15] Yes ? No ? ? ? ? ?
MINIX 3 kernel Some[7][8] No Yes[6] No No No No No No No No No ? ? ? ? ?
NetBSD kernel Yes Yes Yes ? ? ? Yes ? Yes ? ? ? ? ? ? ? ?
ReactOS kernel ? ? ? ? ? ? ? ? Yes ? ? ? ? ? ? ? ?
Solaris kernel Yes[16] No Yes[17] No No No No No Some[18] No ? ? ? ? ? ? ?
Windows NT kernel No No No No No No No No Yes No No No ? ? ? ? ?
XNU No No No No No No Yes No No No No No No No No No No

File system support[edit]

Physical file systems:

Kernel Acorn ADFS Amiga FFS BeFS BFS cramfs EFS ext2 ext3 ext4 FAT FreeVxFS HFS HFS+ HPFS ISO 9660 JFFS JFFS2 JFS MINIX fs NSS NTFS OCFS QNX4 FS System V FS UDF UFS XFS ZFS ReiserFS Reiser4 Btrfs HAMMER Tux3 exFAT
FreeBSD kernel No No No No No No Yes Yes No Yes No No No No Yes No No No No No limited write No No No Yes Yes read only Yes read only No No No No ?
Linux kernel Yes
[19]
Yes read only Yes Yes read only Yes Yes Yes Yes read only Yes limited write (only with empty journal) Yes Yes Yes Yes Yes Yes Yes limited write
[20]
Yes Yes
[19]
[21]
write support? Yes Yes
[19]
Yes both FUSE and native Yes Yes Yes No Yes (experimental patch is available[22])
MINIX 3 kernel No No No No No No Yes No No Tools available, cannot mount No No No No Yes No No No Yes No No No No No No No No No No No No No No No
NetWare kernel No No No No No No No No No Yes No No No No Yes No No No No Yes No No No No Yes No No No No No No No No ?
ReactOS kernel No No No No No No No No No Yes[23] No No No No Yes[23] No No No No No No No No No Yes[23] No No No No No No No No No
Solaris kernel ? ? ? ? ? ? Yes ? ? Yes ? ? ? ? Yes ? ? ? ? No No ? ? ? Yes Yes ? Yes No No No No No ?
Windows NT kernel ? ? ? ? ? ? Yes
[24]
Yes
[25]
? Yes ? Yes
[25]
Yes
[25]
No Yes ? ? ? ? No Yes ? ? ? Yes ? ? No No No No No No Yes
XNU No No No No No No Yes
[26]
Yes
[26]
No Yes No Yes Yes No Yes No No No No No limited write No No No Yes Yes No read only No No No No No Yes

Networked file system support[edit]

Kernel Name NFS AFS CIFS Coda 9P Ceph
FreeBSD kernel Yes Yes Yes Yes No No
Linux kernel Yes Yes Yes Yes Yes Yes
Solaris kernel Yes Yes Yes No No No
Windows NT kernel Yes Yes Yes No No No
XNU Yes Yes Yes No No No

Supported CPU instruction sets and microarchitectures[edit]

kernel DEC ARM Holdings HP Intel MIPS Technologies AIM IBM Renesas Electronics Sun Microsystems Motorola Analog Devices Xilinx Renesas Electronics Tensilica Axis Communications Fujitsu Atmel Panasonic Hyperstone Altera WDC Sunplus Technology Tilera Texas Instruments
VAX Alpha ARM PA-RISC x86 i960 IA-64 MIPS


PowerPC System/
390
z/Architecture H8300 M16C M32R SuperH


SPARC m68k Blackfin (nommu) MicroBlaze 78K V850 Xtensa ETRAX CRIS FR-V AVR32 MN10300 E1 (nommu) Nios (nommu) Nios II WDC 65C816 S+core Tilera C6X
mmu nommu x86 x86-64 mmu nommu 32-bit 64-bit mmu nommu 32-bit 64-bit nommu mmu nommu mmu nommu mmu nommu
DragonFly BSD kernel ? No No No No Yes Yes ? No No No No No No No ? ? ? No No No No No No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
FreeBSD kernel No No Yes ? No Yes Yes ? Yes Yes No Yes Yes No No ? ? ? No No No Yes ? No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Linux kernel No Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No (dropped in 2.6.x) Yes Yes Yes Yes Yes Yes No No Yes Yes No Yes Yes Yes
MINIX 3 kernel ? No In progress ? No Yes In progress No No In progress ? No No No No No ? No No No No No No No No No No ? No No No No No No No No No No No No No No No
NetBSD kernel Yes Yes Yes No[27] Yes Yes Yes ? Yes Yes No[27] Yes No No No ? ? ? Yes No[27] Yes Yes No[27] Yes No[27] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
NetWare kernel No No No No No Yes No ? No No No No No No No ? ? ? No No No No No No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
OpenBSD kernel Yes Yes Yes ? Yes Yes Yes ? No Yes ? Yes No No No ? ? ? Yes ? Yes Yes ? Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Rockbox kernel ? ? Yes ? ? ? ? ? ? Yes ? ? ? ? No ? ? ? Yes ? ? ? ? Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Solaris kernel No No No No No Yes Yes ? No No No No No No No ? ? ? No No Yes Yes ? No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Windows NT kernel No NT 5.0 RC1 and below only Yes No No Yes Yes No Yes NT 4.0 and below only No NT 3.51 and NT 4.0 only No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No
Windows CE kernel No No Yes ? No Yes ? No No Yes ? No No No No No ? No Yes ? No No No No No No No ? No No No No No No No No No No No No No No No
XNU No No Yes ? No Yes Yes ? No No No Yes Yes No No ? ? ? No No No No No No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
SPARTAN kernel ? No Yes ? No Yes Yes ? Yes Yes ? Yes In Progress No No ? ? ? No No No Yes ? No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
FreeRTOS kernel ? ? ? Yes ? ? ? ? ? ? ? Yes ? ? No ? ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes ? ? ? ? Yes ? ? ? ? Yes ? ? ? ?

Supported kernel execution environment[edit]

Kernel name Linux Darwin Windows NT FreeBSD NetBSD Solaris OSF/1 Amiga Unix SunOS BSD/OS IBCS2 systems IRIX Ultrix NDIS SVR4
FreeBSD kernel Yes[28] No No Yes No No No No No No No No No Yes[28] Yes[28]
Linux kernel Yes No No No No No No No No No No No No No No
NetBSD kernel Yes[29] No? [15]? No? [16]? Yes[29] Yes Yes[29] Yes[29] Yes[29] Yes[29] Yes[29] Yes[29] Yes[29] Yes[29] Yes [17] Yes
OpenBSD kernel Yes No No Yes Yes Yes No No Yes ? ? ? ? No Yes
Windows NT kernel No No Yes No No No No No No No No No No No No
ReactOS kernel No No Yes No No No No No No No No No No No No
XNU No Yes No No No No No No No No No No No No No
Kernel name Linux Darwin Windows NT FreeBSD NetBSD Solaris OSF/1 Amiga Unix SunOS BSD/OS IBCS2 systems IRIX Ultrix NDIS SVR4

Supported cipher algorithms[edit]

This may be usable on some situations like file system encrypting.

Kernel name DES AES Blowfish Triple DES Serpent Twofish CAST-128 DES-X IDEA RC2 RC5 SEED Skipjack TEA XTEA CAST-256 RC4 Camellia Anubis KHAZAD Salsa20 FCrypt
Linux Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes
Windows NT kernel Yes Yes Yes Yes No No No No No Yes No No No No No No Yes No No No No No
FreeBSD kernel Yes Yes Yes Yes No No Yes No Yes No No No Yes No No Yes Yes Yes No No No No
Kernel name DES AES Blowfish Triple DES Serpent Twofish CAST-128 DES-X IDEA RC2 RC5 SEED Skipjack TEA XTEA CAST-256 RC4 Camellia Anubis KHAZAD Salsa20 FCrypt

Supported compression algorithms[edit]

This may be usable on some situations like compression file system.

Kernel name Deflate zlib LZO LZJB gzip
Linux Yes Yes Yes ? Yes
Solaris kernel ? ? ? Yes Yes

Supported hash algorithms[edit]

Kernel name CRC-32 (IEEE) CRC32c MD2 MD4 MD5 SHA-1 SHA-256 SHA-384 SHA-512 Michael MIC RIPEMD-128 RIPEMD-160 RIPEMD-256 RIPEMD-320 Tiger Whirlpool HMAC MDC2 GOST LASH-160 LASH-256 LASH-384 LASH-512
Linux Yes[30] Yes[31] Yes[32] Yes Yes Yes Yes Yes[33] Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ?
Solaris kernel Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes ? ? Yes ? Yes Yes ? ? ? ? ?
Windows NT kernel ? ? Yes Yes Yes Yes Yes Yes Yes No No No No No No No Yes No No No No No No
FreeBSD kernel Yes Yes ? Yes Yes Yes Yes Yes Yes ? ? Yes ? ? Yes ? Yes ? ? ? ? ? ?
Kernel name CRC-32 (IEEE) CRC32c MD2 MD4 MD5 SHA-1 SHA-256 SHA-384 SHA-512 Michael MIC RIPEMD-128 RIPEMD-160 RIPEMD-256 RIPEMD-320 Tiger Whirlpool HMAC MDC2 GOST LASH-160 LASH-256 LASH-384 LASH-512

Supported Bluetooth protocols[edit]

Kernel name ACL SCO LMP HCI L2CAP BNEP RFComm. SDP TCP AVTCP AVDTP OBEX CMTP HIDP HCRP CAPI PPP
FreeBSD kernel ? ? ? Yes Yes ? Yes Yes ? ? ? ? ? ? ? ? ?
Linux ? Yes ? Yes Yes Yes Yes ? ? ? ? ? Yes Yes ? ? ?
Kernel name ACL SCO LMP HCI L2CAP BNEP RFComm. SDP TCP AVTCP AVDTP OBEX CMTP HIDP HCRP CAPI PPP

See also[edit]

Footnotes[edit]

  1. ^ IBM PC Real Time Clock should run in UT
  2. ^ The Amiga hardware lacked support for memory protection, so the strong isolation goals of the microkernel design could not be achieved.[citation needed]
  3. ^ http://www.freebsd.org/doc/en/books/handbook/fs-acl.html
  4. ^ http://hydra.nixos.org/jobset/gnu/hurd-master
  5. ^ a b c "The Fiasco microkernel - Status". Retrieved January 11, 2013. 
  6. ^ a b Supports ELF since version 3.2.0 "MinixReleases". Minix Wiki. Retrieved 21 May 2012. 
  7. ^ a b a.out will be phased out in coming releases. van der Kouwe, Erik. "Re: ~Segmentation [Was: Minix3 for sparc]". Minix3 for sparc. Google Groups. Retrieved 21 May 2012. 
  8. ^ a b Commit to remove a.out utils from minix; only supports running a.out now. Leca, Antoine. "3fb8cb760c9075fab05682b89b1542d66481ba58". minix.git. Retrieved 21 May 2012. 
  9. ^ "Announcing NetBSD 5.0". 
  10. ^ http://msdn.microsoft.com/en-us/library/windows/desktop/bb968803%28v=vs.85%29.aspx
  11. ^ https://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html
  12. ^ OpenSolaris Project Weaves CIFS Server Into the Solaris Kernel
  13. ^ a b Integrated Load Balancer
  14. ^ AmigaOS up to version 3.9 could use the ELF format for PowerPC executables and libraries through ppc.library, also known as PowerUP. AmigaOS 4, uses ELF as its native executable format.
  15. ^ The Linux kernel can recognize PE binaries through binfmt_misc and run them using Wine
  16. ^ to support SunOS 4.x binaries
  17. ^ including a Linux compatibility option
  18. ^ The Solaris kernel can PE using Wine
  19. ^ a b c experimental and dangerous write support
  20. ^ The only supported operation is overwriting existing files, without changing the file length so a loop file on a ntfs volume can be written; better write support can be achieved through ntfs-3g, although that is a FUSE filesystem and therefore not strictly a kernel feature
  21. ^ write support currently broken
  22. ^ Fat64 / exFat fs and Linux
  23. ^ a b c Version Status - ReactOS
  24. ^ additional driver needed - see http://www.fs-driver.org/
  25. ^ a b c additional driver needed
  26. ^ a b Third party module required. Mac OS X Kernel Module available here
  27. ^ a b c d e NetBSD Projects - Support for MMU-less systems
  28. ^ a b c Linux emulation in FreeBSD - 2 A look inside...
  29. ^ a b c d e f g h i j NetBSD Binary Emulation
  30. ^ [1]
  31. ^ [2]
  32. ^ MD2 Linux man page
  33. ^ GNU SHA2 utilities