Compile-time errors using Dub/DMD - missing dependencies

[Cassandra Nix via Digitalmars-d]

New questions are sorry, but I have a few minor problems. Where
can I find / install these dependencies?

/usr/bin/ld: cannot find -levent
/usr/bin/ld: cannot find -levent_pthreads
/usr/bin/ld: cannot find -lssl
/usr/bin/ld: cannot find -lcrypto