Hi Friends, My open-ldap server is Version: 2.4.46 OS: redhat7 I set the parameter about cipher suite in client(ldap.conf) and server (slapd.conf) and restart the service, the tcp/ip log, find the cipher not changed. In ldap.conf: TLS_CIPHER_SUITE ALL:!TLSv1.3 In slapd.conf: TLSCipherSuite !TLSv1.3 openssl provide those cipher suites: [root@ ~]# openssl ciphers -v 'TLSv1.3' TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD when openldap worked as a client, it send 4 cipher suites to server in TLS1.3 client hello. Cipher Suite: TLS_EMPTY_RENEGOTIATION_INFO_SCSV (0x00ff) Cipher Suite: TLS_EMPTY_RENEGOTIATION_INFO_SCSV (0x00ff) Cipher Suite: TLS_CHACHA20_POLY1305_SHA256 (0x1303) Cipher Suite: TLS_AES_256_GCM_SHA384 (0x1302) When openldap worked as a server, it used TLS_AES_256_GCM_SHA384 to connect in TLS server hello. And when i set one specific cipher in client, TLS_CIPHER_SUITE TLS_CHACHA20_POLY1305_SHA256 It also send same four suites in client hello. Could you help me to have a look? thanks.