How to fix: fatal error: openssl/opensslv.h: No such file or directory in RedHat 7
To fix this problem, you have to install OpenSSL development package, which is available in standard repositories of all modern Linux distributions.
To install OpenSSL development package on Debian, Ubuntu or their derivatives:
$ sudo apt-get install libssl-dev
To install OpenSSL development package on Fedora, CentOS or RHEL:
$ sudo yum install openssl-devel
Edit : As @isapir has pointed out, for Fedora version>=22 use the DNF package manager :
dnf install openssl-devel
For Alpine Linux:
apk add openssl-dev
On CYGwin, you can install this as a typical package in the first screen. Look for
libssl-devel