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Posted on December 05, 2007


[Installation on Windows, OpenVMS and MacOS (before MacOS X) is described

To install OpenSSL, you will need:

* Perl 5
* an ANSI C compiler
* a supported Unix operating system

Quick Start

If you want to just get on with it, do:

$ ./config
$ make
$ make test
$ make install

[If any of these steps fails, see section Installation in Detail below.]

This will build and install OpenSSL in the default location, which is (for
historical reasons) /usr/local/ssl. If you want to install it anywhere else,
run config like this:

$ ./config –prefix=/usr/local –openssldir=/usr/local/openssl

Configuration Options

There are several options to ./config (or ./Configure) to customize
the build:

–prefix=DIR Install in DIR/bin, DIR/lib, DIR/include/openssl.
Configuration files used by OpenSSL will be in DIR/ssl
or the directory specified by –openssldir.

–openssldir=DIR Directory for OpenSSL files. If no prefix is specified,
the library files and binaries are also installed there.

rsaref Build with RSADSI’s RSAREF toolkit (this assumes that
librsaref.a is in the library search path).

no-threads Don’t try to build with support for multi-threaded

threads Build with support for multi-threaded applications.
This will usually require additional system-dependent options!
See “Note on multi-threading” below.

no-shared Don’t try to create shared libraries.

shared In addition to the usual static libraries, create shared
libraries on platforms where it’s supported. See “Note on
shared libraries” below.

no-asm Do not use assembler code.

386 Use the 80386 instruction set only (the default x86 code is
more efficient, but requires at least a 486).

no- Build without the specified cipher (bf, cast, des, dh, dsa,
hmac, md2, md5, mdc2, rc2, rc4, rc5, rsa, sha).
The crypto/ directory can be removed after running
“make depend”.

-Dxxx, -lxxx, -Lxxx, -fxxx, -Kxxx These system specific options will
be passed through to the compiler to allow you to
define preprocessor symbols, specify additional libraries,
library directories or other compiler options.

Installation in Detail

1a. Configure OpenSSL for your operation system automatically:

$ ./config [options]

This guesses at your operating system (and compiler, if necessary) and
configures OpenSSL based on this guess. Run ./config -t to see
if it guessed correctly. If you want to use a different compiler, you
are cross-compiling for another platform, or the ./config guess was
wrong for other reasons, go to step 1b. Otherwise go to step 2.

On some systems, you can include debugging information as follows:

$ ./config -d [options]

1b. Configure OpenSSL for your operating system manually

OpenSSL knows about a range of different operating system, hardware and
compiler combinations. To see the ones it knows about, run

$ ./Configure

Pick a suitable name from the list that matches your system. For most
operating systems there is a choice between using “cc” or “gcc”. When
you have identified your system (and if necessary compiler) use this name
as the argument to ./Configure. For example, a “linux-elf” user would

$ ./Configure linux-elf [options]

If your system is not available, you will have to edit the Configure
program and add the correct configuration for your system. The
generic configurations “cc” or “gcc” should usually work on 32 bit

Configure creates the file Makefile.ssl from and
defines various macros in crypto/opensslconf.h (generated from

2. Build OpenSSL by running:

$ make

This will build the OpenSSL libraries (libcrypto.a and libssl.a) and the
OpenSSL binary (“openssl”). The libraries will be built in the top-level
directory, and the binary will be in the “apps” directory.

If “make” fails, look at the output. There may be reasons for
the failure that isn’t a problem in OpenSSL itself (like missing
standard headers). If it is a problem with OpenSSL itself, please
report the problem to (note that your
message will be forwarded to a public mailing list). Include the
output of “make report” in your message.

[If you encounter assembler error messages, try the “no-asm”
configuration option as an immediate fix.]

Compiling parts of OpenSSL with gcc and others with the system
compiler will result in unresolved symbols on some systems.

3. After a successful build, the libraries should be tested. Run:

$ make test

If a test fails, look at the output. There may be reasons for
the failure that isn’t a problem in OpenSSL itself (like a missing
or malfunctioning bc). If it is a problem with OpenSSL itself,
try removing any compiler optimization flags from the CFLAGS line
in Makefile.ssl and run “make clean; make”. Please send a bug
report to , including the output of
“make report”.

4. If everything tests ok, install OpenSSL with

$ make install

This will create the installation directory (if it does not exist) and
then the following subdirectories:

certs Initially empty, this is the default location
for certificate files.
man/man1 Manual pages for the ‘openssl’ command line tool
man/man3 Manual pages for the libraries (very incomplete)
misc Various scripts.
private Initially empty, this is the default location
for private key files.

If you didn’t choose a different installation prefix, the
following additional subdirectories will be created:

bin Contains the openssl binary and a few other
utility programs.
include/openssl Contains the header files needed if you want to
compile programs with libcrypto or libssl.
lib Contains the OpenSSL library files themselves.

Package builders who want to configure the library for standard
locations, but have the package installed somewhere else so that
it can easily be packaged, can use

$ make INSTALL_PREFIX=/tmp/package-root install

(or specify “–install_prefix=/tmp/package-root” as a configure
option). The specified prefix will be prepended to all
installation target filenames.

NOTE: The header files used to reside directly in the include
directory, but have now been moved to include/openssl so that
OpenSSL can co-exist with other libraries which use some of the
same filenames. This means that applications that use OpenSSL
should now use C preprocessor directives of the form


instead of “#include “, which was used with library versions
up to OpenSSL 0.9.2b.

If you install a new version of OpenSSL over an old library version,
you should delete the old header files in the include directory.

Compatibility issues:

* COMPILING existing applications

To compile an application that uses old filenames — e.g.
“#include ” –, it will usually be enough to find
the CFLAGS definition in the application’s Makefile and
add a C option such as


to it.

But don’t delete the existing -I option that points to
the …./include directory! Otherwise, OpenSSL header files
could not #include each other.

* WRITING applications

To write an application that is able to handle both the new
and the old directory layout, so that it can still be compiled
with library versions up to OpenSSL 0.9.2b without bothering
the user, you can proceed as follows:

– Always use the new filename of OpenSSL header files,
e.g. #include .

– Create a directory “incl” that contains only a symbolic
link named “openssl”, which points to the “include” directory
of OpenSSL.
For example, your application’s Makefile might contain the
following rule, if OPENSSLDIR is a pathname (absolute or
relative) of the directory where OpenSSL resides:

-mkdir incl
cd $(OPENSSLDIR) # Check whether the directory really exists
-ln -s `cd $(OPENSSLDIR); pwd`/include incl/openssl

You will have to add “incl/openssl” to the dependencies
of those C files that include some OpenSSL header file.

– Add “-Iincl” to your CFLAGS.

With these additions, the OpenSSL header files will be available
under both name variants if an old library version is used:
Your application can reach them under names like ,
while the header files still are able to #include each other
with names of the form .

Note on multi-threading

For some systems, the OpenSSL Configure script knows what compiler options
are needed to generate a library that is suitable for multi-threaded
applications. On these systems, support for multi-threading is enabled
by default; use the “no-threads” option to disable (this should never be

On other systems, to enable support for multi-threading, you will have
to specify at least two options: “threads”, and a system-dependent option.
(The latter is “-D_REENTRANT” on various systems.) The default in this
case, obviously, is not to include support for multi-threading (but
you can still use “no-threads” to suppress an annoying warning message
from the Configure script.)

Note on shared libraries

For some systems, the OpenSSL Configure script knows what is needed to
build shared libraries for libcrypto and libssl. On these systems,
the shared libraries are currently not created by default, but giving
the option “shared” will get them created. This method supports Makefile
targets for shared library creation, like linux-shared. Those targets
can currently be used on their own just as well, but this is expected
to change in future versions of OpenSSL.