I'm having problems trying to get wildcard matching working with OpenSSL. Full hostname matching is working fine, but when my certification uses a wildcard I always get an error. That includes both with OpenSSL 1.1.1b linked into my normal client, AND with the openssl CLI with a system default version. However, trying to use this same certificate and hostname matching works fine with Java and Python clients. Note for my C client I have not set any special flags for matching, I'm just using the default and using SSL_set1_host() to add the hostname. But, I can't even get it to work with openssl itself. I feel like I must be missing something dumb. Any pointers appreciated! For example, here's a connection attempt using the CLI... note if I remove the -verify_hostname option the connection works fine: $ openssl s_client -connect admin0.domain:8004 \ -CAfile ca.cert -verify_hostname admin0.domain CONNECTED(00000003) depth=1 C = US, ST = MA, L = Boston, O = Mycorp, OU = Eng, CN = ca.mycorp.com verify return:1 depth=0 CN = *.domain verify return:1 --- Certificate chain 0 s:/CN=*.domain i:/C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=ca.mycorp.com 1 s:/C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=ca.mycorp.com i:/C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=ca.mycorp.com --- Server certificate -----BEGIN CERTIFICATE----- ... -----END CERTIFICATE----- subject=/CN=*.domain issuer=/C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=ca.mycorp.com --- Acceptable client certificate CA names /C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=nuocmd.mycorp.com /C=US/ST=MA/L=Boston/O=Mycorp/OU=Eng/CN=ca.mycorp.com Client Certificate Types: RSA sign, DSA sign, ECDSA sign Requested Signature Algorithms: ... Shared Requested Signature Algorithms: ... Peer signing digest: SHA512 Server Temp Key: ECDH, P-256, 256 bits ... --- SSL-Session: Protocol : TLSv1.2 Cipher : ECDHE-RSA-AES256-GCM-SHA384 Session-ID: ... Session-ID-ctx: Master-Key: ... Key-Arg : None Krb5 Principal: None PSK identity: None PSK identity hint: None Start Time: 1560181877 Timeout : 300 (sec) Verify return code: 62 (Hostname mismatch)