This is the relatively old issue with OpenSSH 'configure' on AIX 7.1 with non-shared OpenSSL ver. 1.1.1k libs "libcrypto.a" and "libssl.a". The "configure" command is ./configure --prefix=/usr/local/openssh --with-ssl-dir=/usr/local/openssl --with-zlib=/usr/local/zlib --without-openssl-header-check --with-cflags=-q64 --with-ldflags=-q64 and produces this error: configure: error: *** working libcrypto not found, check config.log The following entries were found in "config.log": configure:13292: cc -qlanglvl=extc89 -o conftest -g -q64 -I/usr/local/openssl/include -I/usr/local/zlib/include -L/usr/local/openssl/lib -L/us r/local/zlib/lib -q64 conftest.c -lcrypto -lz >&5 ld: 0711-317 ERROR: Undefined symbol: .pthread_atfork ld: 0711-317 ERROR: Undefined symbol: .pthread_once ld: 0711-317 ERROR: Undefined symbol: .pthread_self ld: 0711-317 ERROR: Undefined symbol: .pthread_key_delete ld: 0711-317 ERROR: Undefined symbol: .pthread_setspecific ld: 0711-317 ERROR: Undefined symbol: .pthread_getspecific ld: 0711-317 ERROR: Undefined symbol: .pthread_key_create ld: 0711-317 ERROR: Undefined symbol: .pthread_rwlock_unlock ld: 0711-317 ERROR: Undefined symbol: .pthread_rwlock_wrlock ld: 0711-317 ERROR: Undefined symbol: .pthread_rwlock_rdlock ld: 0711-317 ERROR: Undefined symbol: .pthread_rwlock_init ld: 0711-317 ERROR: Undefined symbol: .pthread_rwlock_destroy ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information. configure:13292: $? = 8 <skip> ... <skip> configure:13295: error: *** working libcrypto not found, check config.log Based on "configure:13295" error, multiple attempts were made to fix that and the remedy was to add "--with-libs=-lpthread" option: ./configure --prefix=/usr/local/openssh --with-ssl-dir=/usr/local/openssl --with-zlib=/usr/local/zlib --without-openssl-header-check --with-cflags=-q64 --with-ldflags=-q64 -with-libs=-lpthread Another verified approach is to replace LIBS="-lcrypto $LIBS" with LIBS="-lcrypto -lpthread $LIBS" in "configure" script. The initial error is misleading as referring to "libcrypto" while it actually related to "libpthread" not declared - have an impression that, this was started with OpenSSH 8.x release. Because "configure" is not capable to rresolve this, pls advise if configuring OpenSSH on a host with OpenSSL complied with "no-shared" option should always use "-with-libs=-lpthread" option or make change with "LIBS" as outlined above - if that is a case then need to have a note in documentation/README, while it would be better to add the logic into the "configure" script in order to evaluate if adding "-lpthread" in LIBS line (see above) is required in a specific case. Thank you. Val