Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2013. The current version is 1.91.0.

ssl::context_base::verify_mode

Bitmask type for peer verification.

typedef int verify_mode;