How To Install OpenSSL Development Libraries On Ubuntu?

Using APT Package Manager

To install the OpenSSL development libraries on Ubuntu, use this command:

sudo apt-get install libssl-dev

This command installs the libssl-dev package, which has the header files and static libraries for OpenSSL development. The libssl-dev package is needed for compiling programs that use OpenSSL functions. It provides the header files (like openssl/bio.h, openssl/buffer.h, etc.) that were missing in the original error messages. By installing this package, you make these headers available to the compiler, allowing it to find the required OpenSSL declarations and definitions during the build process.

openssl version
dpkg -L libssl-dev | grep '\.h'

Checking for Installed Headers

After installing the OpenSSL development libraries, check if the header files are present and accessible. You can do this by checking specific locations on your Ubuntu system.

To verify the presence of OpenSSL header files, use this command:

ls /usr/include/openssl

This command lists the contents of the OpenSSL include directory. You should see files like bio.h, buffer.h, des.h, evp.h, pem.h, and rsa.h among others.

Common locations for installed development libraries on Ubuntu include:

• /usr/include: This directory contains header files.
• /usr/lib: This directory contains library files.

For OpenSSL, you can find the libraries in:

/usr/lib/x86_64-linux-gnu

To check if the OpenSSL libraries are installed in this location, use:

ls /usr/lib/x86_64-linux-gnu/libssl*

This command shows the OpenSSL library files in the standard library directory.

By confirming the presence of these files in these locations, you can be sure that the OpenSSL development libraries are correctly installed on your Ubuntu system.

openssl version -a

Updating Compiler Flags

After installing the OpenSSL development libraries, you may need to update your compiler flags to fix compilation issues. This involves two steps: adding include paths and linking against the OpenSSL library.

To add include paths, use the -I flag with your compiler command. This tells the compiler where to find header files. For OpenSSL, add:

-I/usr/include/openssl

To link against the OpenSSL library, use the -l flag followed by the library name. For OpenSSL, add:

-lssl -lcrypto

Here's an example of a compilation command:

g++ -I/usr/include/openssl your_file.cpp -o your_program -lssl -lcrypto

If you use a Makefile, add these flags to your CXXFLAGS and LDFLAGS variables:

CXXFLAGS += -I/usr/include/openssl
LDFLAGS += -lssl -lcrypto

g++ -I/usr/include/openssl-1.1 your_file.cpp -o your_program -lssl.1.1 -lcrypto.1.1

Building OpenSSL from Source

You might need to build OpenSSL from source when you need a specific version not available in the Ubuntu repositories, or when you want to customize the build with specific features.

Build OpenSSL from source in these situations:

• You need a newer version than what's in the Ubuntu repositories
• You want to enable or disable specific OpenSSL features
• You're working on a system with limited internet access and need to install OpenSSL manually

Here's an overview of the process to build OpenSSL from source:

1. Download the OpenSSL source code from the official website
2. Extract the downloaded archive
3. Configure the build with your desired options
4. Compile the source code
5. Install the compiled binaries

Basic commands to build OpenSSL from source:

wget https://www.openssl.org/source/openssl-1.1.1k.tar.gz
tar -xzf openssl-1.1.1k.tar.gz
cd openssl-1.1.1k
./config
make
sudo make install

Replace the version number with the one you want to install. After installation, you might need to update your system's library cache by running sudo ldconfig.

Building from source gives you more control over the OpenSSL installation, but it takes more time and technical knowledge than using the package manager.

openssl version