I'm trying to install Tor on my Mac but it shows the following error:

/Applications/Xcode.app/Contents/Developer/usr/bin/make  all-am
  CCLD     src/or/tor
Undefined symbols for architecture x86_64:
  "_SSL_set_session_secret_cb", referenced from:
      _tor_tls_new in libor-crypto.a(tortls.o)
      _tor_tls_session_secret_cb in libor-crypto.a(tortls.o)
  "_EVP_aes_128_ctr", referenced from:
      _aes_new_cipher in libor-crypto.a(aes.o)
  "_CRYPTO_THREADID_set_numeric", referenced from:
      _tor_set_openssl_thread_id in libor-crypto.a(crypto.o)
  "_CRYPTO_THREADID_set_callback", referenced from:
      _crypto_early_init in libor-crypto.a(crypto.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[1]: *** [src/or/tor] Error 1
make: *** [all] Error 2
  • Are you trying to manually build from the source code? Nov 25, 2015 at 18:30
  • yeah!! I am trying to build from the source code!
    – siddhartha
    Nov 25, 2015 at 18:39

1 Answer 1


This is a linker error, meaning you're (probably) missing a library that's required for Tor to build properly.

Undefined symbols for architecture x86_64: "_SSL_set_session_secret_cb", referenced from: _tor_tls_new in libor-crypto.a(tortls.o)

These mean that the Tor code is trying to use _SSL_set_session_secret_cb, _EVP_aes_128_ctr, _CRYPTO_THREADID_set_numeric, and _CRYPTO_THREADID_set_callback, but can't find them. This means they must reside in some code - probably a library - that either isn't on your machine, or is in the "wrong" place. (i.e. A place where the compiler doesn't know to look.)

A quick Google shows that they're part of OpenSSL, which suggests that libssl isn't present.

Assuming you're on Ubuntu (or another Debian-based system), you can following the instructions described here to either install the library, or check it's in the correct place.

To install on Mac, see this thread: https://stackoverflow.com/questions/9874728/openssl-install-issue-to-mac


In fact, full details of the libraries that are required are included in a previous (Ubuntu-related) thread: How can I install Tor from the source code in the Git repository?

  • I am on a mac and I really can't get the help!
    – siddhartha
    Nov 25, 2015 at 19:10
  • I'll attempt to add some Mac instructions. (Sorry for not clearly reading the title... ) Nov 25, 2015 at 19:55
  • As an aside, is there a particular reason why you're building from source instead of just using one of the packages? Nov 25, 2015 at 19:58
  • Nothing just want anonymity for all my browsers! So building it from the core and I am getting screwed up!
    – siddhartha
    Nov 25, 2015 at 20:30
  • Okay, instead of building from source, you could a) install the Tor Browser Bundle, or b) install Tor itself and then configure your other browsers to use it as a SOCKS proxy. Note that option a) is very much the recommended way of doing things. (Trying to configure another browser, e.g. Chrome, to be completely anonymous is difficult... ) Nov 25, 2015 at 20:44

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