Hello, According to this thread: http://openssl.6102.n7.nabble.com/config-and-no-zlib-td42924.html it would make sense to execute Configure with both "no-comp" and "zlib" options. If I understand correctly, this would avoid to have the openssl library to use compression for SSL/TLS by default while still having compression available for other purposes (for example, the command line tools). However, using both options leads to a failure here (please see details for openssl-1.0.2f at the end of this message). So, first of all, does it really make sense to configure with both options? Or am I just plain wrong with my understanding of, for example, the INSTALL file, the comments at the beginning of Configure, the reasonings in above thread? Otherwise, perhaps am I missing an obvious step in my configure/build attempts? TIA, Axel Configuring for darwin64-x86_64-cc no-comp [option] OPENSSL_NO_COMP (skip dir) no-gmp [default] OPENSSL_NO_GMP (skip dir) no-jpake [experimental] OPENSSL_NO_JPAKE (skip dir) no-krb5 [krb5-flavor not specified] OPENSSL_NO_KRB5 no-libunbound [experimental] OPENSSL_NO_LIBUNBOUND (skip dir) no-md2 [default] OPENSSL_NO_MD2 (skip dir) no-rc5 [default] OPENSSL_NO_RC5 (skip dir) no-rfc3779 [default] OPENSSL_NO_RFC3779 (skip dir) no-sctp [default] OPENSSL_NO_SCTP (skip dir) no-shared [default] no-ssl-trace [default] OPENSSL_NO_SSL_TRACE (skip dir) no-ssl2 [option] OPENSSL_NO_SSL2 (skip dir) no-store [experimental] OPENSSL_NO_STORE (skip dir) no-unit-test [default] OPENSSL_NO_UNIT_TEST (skip dir) no-zlib-dynamic [default] [?] cc -I.. -I../.. -I../modes -I../asn1 -I../evp -I../../include -DZLIB -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -arch x86_64 -O3 -DL_ENDIAN -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -c -o cms_cd.o cms_cd.c cms_cd.c:131:20: warning: implicit declaration of function 'BIO_f_zlib' is invalid in C99 [-Wimplicit-function-declaration] return BIO_new(BIO_f_zlib()); ^ [?] cc -DMONOLITH -I.. -I../include -DZLIB -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -arch x86_64 -O3 -DL_ENDIAN -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -c -o enc.o enc.c enc.c:468:28: warning: implicit declaration of function 'BIO_f_zlib' is invalid in C99 [-Wimplicit-function-declaration] if ((bzl = BIO_new(BIO_f_zlib())) == NULL) ^ [?] Undefined symbols for architecture x86_64: "_BIO_f_zlib", referenced from: _enc_main in enc.o _cms_CompressedData_init_bio in libcrypto.a(cms_cd.o) ld: symbol(s) not found for architecture x86_64 [?] And indeed, file openssl.conf is built with: # define OPENSSL_NO_COMP Moreover, both files cms_cd.c and enc.c have: #ifndef OPENSSL_NO_COMP # include <openssl/comp.h> #endif so that the definition of BIO_f_zlib() can?t be found. And it appears that "comp" is removed from the SDIRS variable. Playing very dangerously, that is: manually adding comp to SDIRS replacing #ifndef OPENSSL_NO_COMP with #if defined ZLIB || not defined OPENSSL_NO_COMP it seems that make succeeds. Dangerously, because I just don?t know what I am doing, what side-effects I am very likely introducing. ;-)