+ Configuration Options
+ ---------------------
+
+ There are several options to ./config (or ./Configure) to customize
+ the build (note that for Windows, the defaults for --prefix and
+ --openssldir depend in what configuration is used and what Windows
+ implementation OpenSSL is built on. More notes on this in NOTES.WIN):
+
+ --api=x.y.z
+ Don't build with support for deprecated APIs below the
+ specified version number. For example "--api=1.1.0" will
+ remove support for all APIS that were deprecated in OpenSSL
+ version 1.1.0 or below.
+
+ --cross-compile-prefix=PREFIX
+ The PREFIX to include in front of commands for your
+ toolchain. It's likely to have to end with dash, e.g.
+ a-b-c- would invoke GNU compiler as a-b-c-gcc, etc.
+ Unfortunately cross-compiling is too case-specific to
+ put together one-size-fits-all instructions. You might
+ have to pass more flags or set up environment variables
+ to actually make it work. Android and iOS cases are
+ discussed in corresponding Configurations/10-main.cf
+ sections. But there are cases when this option alone is
+ sufficient. For example to build the mingw64 target on
+ Linux "--cross-compile-prefix=x86_64-w64-mingw32-"
+ works. Naturally provided that mingw packages are
+ installed. Today Debian and Ubuntu users have option to
+ install a number of prepackaged cross-compilers along
+ with corresponding run-time and development packages for
+ "alien" hardware. To give another example
+ "--cross-compile-prefix=mipsel-linux-gnu-" suffices
+ in such case. Needless to mention that you have to
+ invoke ./Configure, not ./config, and pass your target
+ name explicitly.
+
+ --debug
+ Build OpenSSL with debugging symbols.
+
+ --libdir=DIR
+ The name of the directory under the top of the installation
+ directory tree (see the --prefix option) where libraries will
+ be installed. By default this is "lib". Note that on Windows
+ only ".lib" files will be stored in this location. dll files
+ will always be installed to the "bin" directory.
+
+ --openssldir=DIR
+ Directory for OpenSSL configuration files, and also the
+ default certificate and key store. Defaults are:
+
+ Unix: /usr/local/ssl
+ Windows: C:\Program Files\Common Files\SSL
+ or C:\Program Files (x86)\Common Files\SSL
+ OpenVMS: SYS$COMMON:[OPENSSL-COMMON]
+
+ --prefix=DIR
+ The top of the installation directory tree. Defaults are:
+
+ Unix: /usr/local
+ Windows: C:\Program Files\OpenSSL
+ or C:\Program Files (x86)\OpenSSL
+ OpenVMS: SYS$COMMON:[OPENSSL-'version']
+
+ --release
+ Build OpenSSL without debugging symbols. This is the default.
+
+ --strict-warnings
+ This is a developer flag that switches on various compiler
+ options recommended for OpenSSL development. It only works
+ when using gcc or clang as the compiler. If you are
+ developing a patch for OpenSSL then it is recommended that
+ you use this option where possible.
+
+ --with-zlib-include=DIR
+ The directory for the location of the zlib include file. This
+ option is only necessary if enable-zlib (see below) is used
+ and the include file is not already on the system include
+ path.
+
+ --with-zlib-lib=LIB
+ On Unix: this is the directory containing the zlib library.
+ If not provided the system library path will be used.
+ On Windows: this is the filename of the zlib library (with or
+ without a path). This flag must be provided if the
+ zlib-dynamic option is not also used. If zlib-dynamic is used
+ then this flag is optional and a default value ("ZLIB1") is
+ used if not provided.
+ On VMS: this is the filename of the zlib library (with or
+ without a path). This flag is optional and if not provided
+ then "GNV$LIBZSHR", "GNV$LIBZSHR32" or "GNV$LIBZSHR64" is
+ used by default depending on the pointer size chosen.
+
+
+ --with-rand-seed=seed1[,seed2,...]
+ A comma separated list of seeding methods which will be tried
+ by OpenSSL in order to obtain random input (a.k.a "entropy")
+ for seeding its cryptographically secure random number
+ generator (CSPRNG). The current seeding methods are:
+
+ os: Use a trusted operating system entropy source.
+ This is the default method if such an entropy
+ source exists.
+ getrandom: Use the L<getrandom(2)> system call if available.
+ devrandom: Use the the first device from the DEVRANDOM list
+ which can be opened to read random bytes. The
+ DEVRANDOM preprocessor constant expands to
+ "/dev/urandom","/dev/random","/dev/srandom" on
+ most unix-ish operating systems.
+ egd: Check for an entropy generating daemon.
+ rdcpu: Use the RDSEED or RDRAND command if provided by
+ the CPU.
+ librandom: Use librandom (not implemented yet).
+ none: Disable automatic seeding. This is the default
+ on some operating systems where no suitable
+ entropy source exists, or no support for it is
+ implemented yet.
+
+ For more information, see the section 'Note on random number
+ generation' at the end of this document.
+
+ no-afalgeng
+ Don't build the AFALG engine. This option will be forced if
+ on a platform that does not support AFALG.
+
+ enable-asan
+ Build with the Address sanitiser. This is a developer option
+ only. It may not work on all platforms and should never be
+ used in production environments. It will only work when used
+ with gcc or clang and should be used in conjunction with the
+ no-shared option.
+
+ no-asm
+ Do not use assembler code. On some platforms a small amount
+ of assembler code may still be used.
+
+ no-async
+ Do not build support for async operations.
+
+ no-autoalginit
+ Don't automatically load all supported ciphers and digests.
+ Typically OpenSSL will make available all of its supported
+ ciphers and digests. For a statically linked application this
+ may be undesirable if small executable size is an objective.
+ This only affects libcrypto. Ciphers and digests will have to
+ be loaded manually using EVP_add_cipher() and
+ EVP_add_digest() if this option is used. This option will
+ force a non-shared build.
+
+ no-autoerrinit
+ Don't automatically load all libcrypto/libssl error strings.
+ Typically OpenSSL will automatically load human readable
+ error strings. For a statically linked application this may
+ be undesirable if small executable size is an objective.
+
+ no-autoload-config
+ Don't automatically load the default openssl.cnf file.
+ Typically OpenSSL will automatically load a system config
+ file which configures default ssl options.
+
+ no-capieng
+ Don't build the CAPI engine. This option will be forced if
+ on a platform that does not support CAPI.
+
+ no-cms
+ Don't build support for CMS features
+
+ no-comp
+ Don't build support for SSL/TLS compression. If this option
+ is left enabled (the default), then compression will only
+ work if the zlib or zlib-dynamic options are also chosen.
+
+ enable-crypto-mdebug
+ Build support for debugging memory allocated via
+ OPENSSL_malloc() or OPENSSL_zalloc().
+
+ enable-crypto-mdebug-backtrace
+ As for crypto-mdebug, but additionally provide backtrace
+ information for allocated memory.
+ TO BE USED WITH CARE: this uses GNU C functionality, and
+ is therefore not usable for non-GNU config targets. If
+ your build complains about the use of '-rdynamic' or the
+ lack of header file execinfo.h, this option is not for you.
+ ALSO NOTE that even though execinfo.h is available on your
+ system (through Gnulib), the functions might just be stubs
+ that do nothing.
+
+ no-ct
+ Don't build support for Certificate Transparency.
+
+ no-deprecated
+ Don't build with support for any deprecated APIs. This is the
+ same as using "--api" and supplying the latest version
+ number.
+
+ no-dgram
+ Don't build support for datagram based BIOs. Selecting this
+ option will also force the disabling of DTLS.
+
+ no-dso
+ Don't build support for loading Dynamic Shared Objects.
+
+ no-dynamic-engine
+ Don't build the dynamically loaded engines. This only has an
+ effect in a "shared" build
+
+ no-ec
+ Don't build support for Elliptic Curves.
+
+ no-ec2m
+ Don't build support for binary Elliptic Curves
+
+ enable-ec_nistp_64_gcc_128
+ Enable support for optimised implementations of some commonly
+ used NIST elliptic curves. This is only supported on some
+ platforms.
+
+ enable-egd
+ Build support for gathering entropy from EGD (Entropy
+ Gathering Daemon).
+
+ no-engine
+ Don't build support for loading engines.
+
+ no-err
+ Don't compile in any error strings.
+
+ enable-external-tests
+ Enable building of integration with external test suites.
+ This is a developer option and may not work on all platforms.
+ The only supported external test suite at the current time is
+ the BoringSSL test suite. See the file test/README.external
+ for further details.
+
+ no-filenames
+ Don't compile in filename and line number information (e.g.
+ for errors and memory allocation).
+
+ enable-fuzz-libfuzzer, enable-fuzz-afl
+ Build with support for fuzzing using either libfuzzer or AFL.
+ These are developer options only. They may not work on all
+ platforms and should never be used in production environments.
+ See the file fuzz/README.md for further details.
+
+ no-gost
+ Don't build support for GOST based ciphersuites. Note that
+ if this feature is enabled then GOST ciphersuites are only
+ available if the GOST algorithms are also available through
+ loading an externally supplied engine.
+
+ no-hw-padlock
+ Don't build the padlock engine.
+
+ no-makedepend
+ Don't generate dependencies.
+
+ no-multiblock
+ Don't build support for writing multiple records in one
+ go in libssl (Note: this is a different capability to the
+ pipelining functionality).
+
+ no-nextprotoneg
+ Don't build support for the NPN TLS extension.
+
+ no-ocsp
+ Don't build support for OCSP.
+
+ no-pic
+ Don't build with support for Position Independent Code.
+
+ no-posix-io
+ Don't use POSIX IO capabilities.
+
+ no-psk
+ Don't build support for Pre-Shared Key based ciphersuites.
+
+ no-rdrand
+ Don't use hardware RDRAND capabilities.
+
+ no-rfc3779
+ Don't build support for RFC3779 ("X.509 Extensions for IP
+ Addresses and AS Identifiers")
+
+ sctp
+ Build support for SCTP
+
+ no-shared
+ Do not create shared libraries, only static ones. See "Note
+ on shared libraries" below.
+
+ no-sock
+ Don't build support for socket BIOs
+
+ no-srp
+ Don't build support for SRP or SRP based ciphersuites.
+
+ no-srtp
+ Don't build SRTP support
+
+ no-sse2
+ Exclude SSE2 code paths from 32-bit x86 assembly modules.
+ Normally SSE2 extension is detected at run-time, but the
+ decision whether or not the machine code will be executed
+ is taken solely on CPU capability vector. This means that
+ if you happen to run OS kernel which does not support SSE2
+ extension on Intel P4 processor, then your application
+ might be exposed to "illegal instruction" exception.
+ There might be a way to enable support in kernel, e.g.
+ FreeBSD kernel can be compiled with CPU_ENABLE_SSE, and
+ there is a way to disengage SSE2 code paths upon application
+ start-up, but if you aim for wider "audience" running
+ such kernel, consider no-sse2. Both the 386 and
+ no-asm options imply no-sse2.
+
+ enable-ssl-trace
+ Build with the SSL Trace capabilities (adds the "-trace"
+ option to s_client and s_server).
+
+ no-static-engine
+ Don't build the statically linked engines. This only
+ has an impact when not built "shared".
+
+ no-stdio
+ Don't use anything from the C header file "stdio.h" that
+ makes use of the "FILE" type. Only libcrypto and libssl can
+ be built in this way. Using this option will suppress
+ building the command line applications. Additionally since
+ the OpenSSL tests also use the command line applications the
+ tests will also be skipped.
+
+ no-tests
+ Don't build test programs or run any test.
+
+ no-threads
+ Don't try to build with support for multi-threaded
+ applications.
+
+ threads
+ Build with support for multi-threaded applications. Most
+ platforms will enable this by default. However if on a
+ platform where this is not the case then this will usually
+ require additional system-dependent options! See "Note on
+ multi-threading" below.
+
+ enable-tls13downgrade
+ TODO(TLS1.3): Make this enabled by default and remove the
+ option when TLSv1.3 is out of draft
+ TLSv1.3 offers a downgrade protection mechanism. This is
+ implemented but disabled by default. It should not typically
+ be enabled except for testing purposes. Otherwise this could
+ cause problems if a pre-RFC version of OpenSSL talks to an
+ RFC implementation (it will erroneously be detected as a
+ downgrade).
+
+ no-ts
+ Don't build Time Stamping Authority support.
+
+ enable-ubsan
+ Build with the Undefined Behaviour sanitiser. This is a
+ developer option only. It may not work on all platforms and
+ should never be used in production environments. It will only
+ work when used with gcc or clang and should be used in
+ conjunction with the "-DPEDANTIC" option (or the
+ --strict-warnings option).
+
+ no-ui
+ Don't build with the "UI" capability (i.e. the set of
+ features enabling text based prompts).
+
+ enable-unit-test
+ Enable additional unit test APIs. This should not typically
+ be used in production deployments.
+
+ enable-weak-ssl-ciphers
+ Build support for SSL/TLS ciphers that are considered "weak"
+ (e.g. RC4 based ciphersuites).
+
+ zlib
+ Build with support for zlib compression/decompression.
+
+ zlib-dynamic
+ Like "zlib", but has OpenSSL load the zlib library
+ dynamically when needed. This is only supported on systems
+ where loading of shared libraries is supported.
+
+ 386
+ In 32-bit x86 builds, when generating assembly modules,
+ use the 80386 instruction set only (the default x86 code
+ is more efficient, but requires at least a 486). Note:
+ This doesn't affect code generated by compiler, you're
+ likely to complement configuration command line with
+ suitable compiler-specific option.
+
+ no-<prot>
+ Don't build support for negotiating the specified SSL/TLS
+ protocol (one of ssl, ssl3, tls, tls1, tls1_1, tls1_2,
+ tls1_3, dtls, dtls1 or dtls1_2). If "no-tls" is selected then
+ all of tls1, tls1_1, tls1_2 and tls1_3 are disabled.
+ Similarly "no-dtls" will disable dtls1 and dtls1_2. The
+ "no-ssl" option is synonymous with "no-ssl3". Note this only
+ affects version negotiation. OpenSSL will still provide the
+ methods for applications to explicitly select the individual
+ protocol versions.
+
+ no-<prot>-method
+ As for no-<prot> but in addition do not build the methods for
+ applications to explicitly select individual protocol
+ versions. Note that there is no "no-tls1_3-method" option
+ because there is no application method for TLSv1.3. Using
+ individual protocol methods directly is deprecated.
+ Applications should use TLS_method() instead.
+
+ enable-<alg>
+ Build with support for the specified algorithm, where <alg>
+ is one of: md2 or rc5.
+
+ no-<alg>
+ Build without support for the specified algorithm, where
+ <alg> is one of: aria, bf, blake2, camellia, cast, chacha,
+ cmac, des, dh, dsa, ecdh, ecdsa, idea, md4, mdc2, ocb,
+ poly1305, rc2, rc4, rmd160, scrypt, seed, siphash, sm3, sm4
+ or whirlpool. The "ripemd" algorithm is deprecated and if
+ used is synonymous with rmd160.
+
+ -Dxxx, -Ixxx, -Wp, -lxxx, -Lxxx, -Wl, -rpath, -R, -framework, -static
+ These system specific options will be recognised and
+ passed through to the compiler to allow you to define
+ preprocessor symbols, specify additional libraries, library
+ directories or other compiler options. It might be worth
+ noting that some compilers generate code specifically for
+ processor the compiler currently executes on. This is not
+ necessarily what you might have in mind, since it might be
+ unsuitable for execution on other, typically older,
+ processor. Consult your compiler documentation.
+
+ Take note of the VAR=value documentation below and how
+ these flags interact with those variables.
+
+ -xxx, +xxx
+ Additional options that are not otherwise recognised are
+ passed through as they are to the compiler as well. Again,
+ consult your compiler documentation.
+
+ Take note of the VAR=value documentation below and how
+ these flags interact with those variables.
+
+ VAR=value
+ Assignment of environment variable for Configure. These
+ work just like normal environment variable assignments,
+ but are supported on all platforms and are confined to
+ the configuration scripts only. These assignments override
+ the corresponding value in the inherited environment, if
+ there is one.
+
+ The following variables are used as "make variables" and
+ can be used as an alternative to giving preprocessor,
+ compiler and linker options directly as configuration.
+ The following variables are supported:
+
+ AR The static library archiver.
+ ARFLAGS Flags for the static library archiver.
+ AS The assembler compiler.
+ ASFLAGS Flags for the assembler compiler.
+ CC The C compiler.
+ CFLAGS Flags for the C compiler.
+ CXX The C++ compiler.
+ CXXFLAGS Flags for the C++ compiler.
+ CPP The C/C++ preprocessor.
+ CPPFLAGS Flags for the C/C++ preprocessor.
+ CPPDEFINES List of CPP macro definitions, separated
+ by a platform specific character (':' or
+ space for Unix, ';' for Windows, ',' for
+ VMS). This can be used instead of using
+ -D (or what corresponds to that on your
+ compiler) in CPPFLAGS.
+ CPPINCLUDES List of CPP inclusion directories, separated
+ the same way as for CPPDEFINES. This can
+ be used instead of -I (or what corresponds
+ to that on your compiler) in CPPFLAGS.
+ HASHBANGPERL Perl invocation to be inserted after '#!'
+ in public perl scripts (only relevant on
+ Unix).
+ LD The program linker (not used on Unix, $(CC)
+ is used there).
+ LDFLAGS Flags for the shared library, DSO and
+ program linker.
+ LDLIBS Extra libraries to use when linking.
+ Takes the form of a space separated list
+ of library specifications on Unix and
+ Windows, and as a comma separated list of
+ libraries on VMS.
+ RANLIB The library archive indexer.
+ RC The Windows resources manipulator.
+ RCFLAGS Flags for the Windows reources manipulator.
+ RM The command to remove files and directories.
+
+ These cannot be mixed with compiling / linking flags given
+ on the command line. In other words, something like this
+ isn't permitted.
+
+ ./config -DFOO CPPFLAGS=-DBAR -DCOOKIE
+
+ Backward compatibility note:
+
+ To be compatible with older configuration scripts, the
+ environment variables are ignored if compiling / linking
+ flags are given on the command line, except for these:
+
+ AR, CC, CXX, CROSS_COMPILE, HASHBANGPERL, PERL, RANLIB, RC
+ and WINDRES
+
+ For example, the following command will not see -DBAR:
+
+ CPPFLAGS=-DBAR ./config -DCOOKIE
+
+ However, the following will see both set variables:
+
+ CC=gcc CROSS_COMPILE=x86_64-w64-mingw32- \
+ ./config -DCOOKIE
+
+ reconf
+ reconfigure
+ Reconfigure from earlier data. This fetches the previous
+ command line options and environment from data saved in
+ "configdata.pm", and runs the configuration process again,
+ using these options and environment.
+ Note: NO other option is permitted together with "reconf".
+ This means that you also MUST use "./Configure" (or
+ what corresponds to that on non-Unix platforms) directly
+ to invoke this option.
+ Note: The original configuration saves away values for ALL
+ environment variables that were used, and if they weren't
+ defined, they are still saved away with information that
+ they weren't originally defined. This information takes
+ precedence over environment variables that are defined
+ when reconfiguring.
+
+ Displaying configuration data
+ -----------------------------
+
+ The configuration script itself will say very little, and finishes by
+ creating "configdata.pm". This perl module can be loaded by other scripts
+ to find all the configuration data, and it can also be used as a script to
+ display all sorts of configuration data in a human readable form.
+
+ For more information, please do:
+
+ $ ./configdata.pm --help # Unix
+
+ or
+
+ $ perl configdata.pm --help # Windows and VMS