CMake not able to find OpenSSL library

Question

I am trying to install a software, which uses cmake to install itself, when i give at commandlin cmake ..
it gives me following error in this file, CMakeLists.txt -----

Answer 1

Note for Fedora 27 users: I had to install openssl-devel package to run the cmake successfully.

sudo dnf install openssl-devel

Answer 2

This is what I added in the CMakeList.txt (which worked):

# https://cmake.org/cmake/help/latest/command/find_package.html
# in the above link, it states:
# "In Module mode, CMake searches for a file called Find<PackageName>.cmake. 
#  The file is first searched in the CMAKE_MODULE_PATH, then among the Find 
#  Modules provided by the CMake installation. If the file is found, it is
#  read and processed by CMake. It is responsible for finding the package,
#  checking the version, and producing any needed messages. Some find-modules
#  provide limited or no support for versioning; check the module documentation."
#
# FindOpenSSL.cmake can be found in path/to/cmake/Modules
#
# https://cmake.org/cmake/help/latest/module/FindOpenSSL.html
#

find_package(OpenSSL REQUIRED)
if (OPENSSL_FOUND)
  # Add the include directories for compiling
  target_include_directories(${PROJECT_NAME} PUBLIC ${OPENSSL_INCLUDE_DIR})

  # Add the static lib for linking
  target_link_libraries(${PROJECT_NAME} OpenSSL::SSL OpenSSL::Crypto)

  message(STATUS "Found OpenSSL ${OPENSSL_VERSION}")

else()

  message(STATUS "OpenSSL Not Found")

endif()

Answer 3

I had the same problem (openssl) and this worked for me on Ubuntu 14.04.1 LTS. The solution is the same up to Ubuntu 18.04 (tested).

sudo apt-get install libssl-dev

Answer 4

you are having the FindOpenSSL.cmake file in the cmake module(path usr/shared.cmake-3.5/modules) # Search OpenSSL

 find_package(OpenSSL REQUIRED) 
if( OpenSSL_FOUND )
    include_directories(${OPENSSL_INCLUDE_DIRS})
    link_directories(${OPENSSL_LIBRARIES})
    message(STATUS "Using OpenSSL ${OPENSSL_VERSION}")

target_link_libraries(project_name /path/of/libssl.so /path/of/libcrypto.so)

Answer 5

Same problem, and fixed it on my centos 6.5 using the following command.

yum install openssl-devel

Answer 6

If you can use pkg-config: pkg_search_module() can find OpenSSL for you.

# Search OpenSSL
find_package(PkgConfig REQUIRED)
pkg_search_module(OPENSSL REQUIRED openssl)

if( OPENSSL_FOUND )
    include_directories(${OPENSSL_INCLUDE_DIRS})
    message(STATUS "Using OpenSSL ${OPENSSL_VERSION}")
else()
    # Error; with REQUIRED, pkg_search_module() will throw an error by it's own
endif()

target_link_libraries(${YOUR_TARGET_HERE} ${OPENSSL_LIBRARIES})