please can anyone tell me: Is the 1.0.2g release from : http://www.openssl.org/source/openssl-1.0.2g.tar.gz meant to build ? Is this meant to be the latest stable release , or is that 1.0.1s ? The 1.0.2g release does not build, for the linux-x86_64:gcc 'threads shared' configuration (or any other AFAICS) because it lacks an implementation of rc4_md4_enc() - there are calls to it in crypto/evp/e_rc4_hmac_md5.c , but no definition of it : $ grep -RIn --include '*.[ch]' rc4_md5_enc crypto/evp/e_rc4_hmac_md5.c:80:void rc4_md5_enc(RC4_KEY *key, const void *in0, void *out, crypto/evp/e_rc4_hmac_md5.c:144: rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off, crypto/evp/e_rc4_hmac_md5.c:188: rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off, $ make ... $ ( LIBDEPS="${LIBDEPS:--L.. -lssl -L.. -lcrypto }"; LDCMD="${LDCMD:-gcc}"; LDFLAGS="${LDFLAGS:--DOPENSSL_THREADS -march=x86-64 -mtune=native -O2 -g -fPIC -pipe }"; LIBPATH=`for x in $LIBDEPS; do echo $x; done | sed -e 's/^ *-L//;t' -e d | uniq`; LIBPATH=`echo $LIBPATH | sed -e 's/ /:/g'`; set -x; LD_LIBRARY_PATH=$LIBPATH:$LD_LIBRARY_PATH ${LDCMD} ${LDFLAGS} -o ${APPNAME:=openssl} openssl.o verify.o asn1pars.o req.o dgst.o dh.o dhparam.o enc.o passwd.o gendh.o errstr.o ca.o pkcs7.o crl2p7.o crl.o rsa.o rsautl.o dsa.o dsaparam.o ec.o ecparam.o x509.o genrsa.o gendsa.o genpkey.o s_server.o s_client.o speed.o s_time.o apps.o s_cb.o s_socket.o app_rand.o version.o sess_id.o ciphers.o nseq.o pkcs12.o pkcs8.o pkey.o pkeyparam.o pkeyutl.o spkac.o smime.o cms.o rand.o engine.o ocsp.o prime.o ts.o srp.o ${LIBDEPS} ) + LD_LIBRARY_PATH=..: + gcc -DOPENSSL_THREADS -march=x86-64 -mtune=native -O2 -g -fPIC -pipe -o openssl openssl.o verify.o asn1pars.o req.o dgst.o dh.o dhparam.o enc.o passwd.o gendh.o errstr.o ca.o pkcs7.o crl2p7.o crl.o rsa.o rsautl.o dsa.o dsaparam.o ec.o ecparam.o x509.o genrsa.o gendsa.o genpkey.o s_server.o s_client.o speed.o s_time.o apps.o s_cb.o s_socket.o app_rand.o version.o sess_id.o ciphers.o nseq.o pkcs12.o pkcs8.o pkey.o pkeyparam.o pkeyutl.o spkac.o smime.o cms.o rand.o engine.o ocsp.o prime.o ts.o srp.o -L.. -lssl -L.. -lcrypto ../libcrypto.a(e_rc4_hmac_md5.o): In function `rc4_hmac_md5_cipher': /usr/build/linux/openssl-1.0.2g/crypto/evp/e_rc4_hmac_md5.c:144: undefined reference to `rc4_md5_enc' /usr/build/linux/openssl-1.0.2g/crypto/evp/e_rc4_hmac_md5.c:188: undefined reference to `rc4_md5_enc' collect2: error: ld returned 1 exit status ie. the make fails because nowhere in any library or object file is that function defined - I have checked this with nm . I guess my answer is that ! should be building 1.0.1s ?