If you look at what gets installed with the openssl package with
$ pkg_info -L openssl you will see that the openssl library (either version 1.0.2 or version 1.1) is named
eopenssl.
- Whether you begin with the OpenBSD port or not, you will need to provision the build tool chain to point to these include files and library. The Makefile for net/nagios/nrpe shows example changes to $CFLAGS and $LDFLAGS to point its tools to eopenssl.
- I recommend you start with the www/nginx port because it includes OpenBSD-specific patches for nginx, and it has a working build tool chain with a working configuration.