Undefined symbol reference X509_free

Question

I am trying to use the outdated C ++ mongodb driver. (Here, "legacy" means the production version, fwiw.) On the ubuntu host 15.04 using clang ++ 3.6 and raising 1.55 (from the ubuntu package repositories) and using the mongo-cxx driver pulled out the git form, I compiled the driver, and then tried to compile a test program .

$ clang++ -std=c++14 mongo.cc -pthread -lmongoclient -lboost_thread \
  -lboost_system -lboost_regex -lssl -o mo

I see this error:

clang++ -std=c++14 mongo.cc -pthread -lmongoclient -lboost_thread -lboost_system -lboost_regex -lssl -lcrypt -o mo
/usr/bin/ld: /usr/local/lib/libmongoclient.a(ssl_manager.o): undefined reference to symbol 'X509_free@@OPENSSL_1.0.0'
/lib/x86_64-linux-gnu/libcrypto.so.1.0.0: error adding symbols: DSO missing from command line
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Obviously I'm missing X509_free(), but it seems like it should be in libssl (which is openSSL1.0.0, says dpkg and the symbolic library itself).

Thanks so much for any advice.

I don't think this is important here, but this is mongo.cc:

#include <cstdlib>
#include <iostream>
#include "mongo/client/dbclient.h" // for the driver

void run() {
  mongo::DBClientConnection c;
  c.connect("localhost");
}

int main() {
    mongo::client::initialize();
    try {
        run();
        std::cout << "connected ok" << std::endl;
    } catch( const mongo::DBException &e ) {
        std::cout << "caught " << e.what() << std::endl;
    }
    return EXIT_SUCCESS;
}

Answer 1

libcrypto.so, libcrypt.so.