I'm running Stunnel 5.56 under Windows 10 v1909 x64.

I have uncovered a case in which VerifyPeer = yes is not working. What's happening is that the locally installed certificate is old and expired, and does not match the current, up-to-date server certificate, yet Stunnel is letting it pass and verifying okay.  I've pasted the certificates, config, and log below, and clearly the certificates are different.

Regards,

Thomas

From my config file:

debug = 7 delay = yes socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 socket = l:SO_LINGER=1:60 socket = r:SO_LINGER=1:60

[ircs.3] client = yes sslVersionMin = TLSv1.2 cafile = peer-ircs.3.pem verifyPeer = yes accept = 127.0.0.1:8909 connect = halcyon.il.us.dal.net:6697

From the Stunnel log:

2020.02.04 12:41:50 LOG5[9]: Service [ircs.3] connected remote server from 104.231.234.35:62290 2020.02.04 12:41:50 LOG7[9]: Setting remote socket options (FD=1012) 2020.02.04 12:41:50 LOG7[9]: Option SO_LINGER set on remote socket 2020.02.04 12:41:50 LOG7[9]: Option TCP_NODELAY set on remote socket 2020.02.04 12:41:50 LOG7[9]: Remote descriptor (FD=1012) initialized 2020.02.04 12:41:50 LOG6[9]: SNI: sending servername: halcyon.il.us.dal.net 2020.02.04 12:41:50 LOG6[9]: Peer certificate required 2020.02.04 12:41:50 LOG7[9]: TLS state (connect): before SSL initialization 2020.02.04 12:41:50 LOG7[9]: TLS state (connect): SSLv3/TLS write client hello 2020.02.04 12:41:50 LOG7[9]: TLS state (connect): SSLv3/TLS write client hello 2020.02.04 12:41:50 LOG7[9]: TLS state (connect): SSLv3/TLS read server hello 2020.02.04 12:41:50 LOG7[9]: TLS state (connect): TLSv1.3 read encrypted extensions 2020.02.04 12:41:50 LOG7[9]: Verification started at depth=1: C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3 2020.02.04 12:41:50 LOG6[9]: CERT: Pre-verification error ignored: unable to get issuer certificate 2020.02.04 12:41:50 LOG6[9]: Certificate accepted at depth=1: C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3 2020.02.04 12:41:50 LOG7[9]: Verification started at depth=0: CN=*.dal.net 2020.02.04 12:41:50 LOG7[9]: CERT: Pre-verification succeeded 2020.02.04 12:41:50 LOG6[9]: CERT: No subject checks configured 2020.02.04 12:41:50 LOG6[9]: CERT: Locally installed certificate matched 2020.02.04 12:41:50 LOG5[9]: Certificate accepted at depth=0: CN=*.dal.net

Here is the locally installed certificate:

-----BEGIN CERTIFICATE----- MIIFeDCCBGCgAwIBAgISA4aqIgapILZTQatLgMyS1gJ7MA0GCSqGSIb3DQEBCwUA MEoxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQD ExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBYMzAeFw0xOTA2MDEwNDEzMjlaFw0x OTA4MzAwNDEzMjlaMBQxEjAQBgNVBAMMCSouZGFsLm5ldDCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAKk+ZRY6Kr4GUS9hU+AUvgUrRzffLS4ScDNvk88F HXKe6Yx3oJnMJEGC9a5I9nJATcItOa+Xk6NKFIsGQZhFOTkV9xvbaEw2KZ14SIKK NsffEqZeQ/TUdMaHTeDXJxj1gfa+W9FK6uO1TzKrYQamdegXAv55F6KLeIPTjZj3 77AkdWuddimY3rp0gK/R1e2tkFtP/0ZeWuu1M736b6dtjXFIhzw3G8wurbGfBgfO TebZL3Kw0X5qOlyMQyOyXXUyRZMqgW7PMloGtGQ/PJKoTzqNmyWO93QB28PGHDm8 WgnSdwgXlTmVrL9Vwnzb5FIfcM1ba5nzqDGeg7tG5RcQEGkCAwEAAaOCAowwggKI MA4GA1UdDwEB/wQEAwIFoDAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIw DAYDVR0TAQH/BAIwADAdBgNVHQ4EFgQUpVm+qZ/cdM/H1vr7emXvf14+/0AwHwYD VR0jBBgwFoAUqEpqYwR93brm0Tm3pkVl7/Oo7KEwbwYIKwYBBQUHAQEEYzBhMC4G CCsGAQUFBzABhiJodHRwOi8vb2NzcC5pbnQteDMubGV0c2VuY3J5cHQub3JnMC8G CCsGAQUFBzAChiNodHRwOi8vY2VydC5pbnQteDMubGV0c2VuY3J5cHQub3JnLzBD BgNVHREEPDA6ggkqLmRhbC5uZXSCDyouaWwudXMuZGFsLm5ldIIOKi5pcHY2LmRh bC5uZXSCDCoudXMuZGFsLm5ldDBMBgNVHSAERTBDMAgGBmeBDAECATA3BgsrBgEE AYLfEwEBATAoMCYGCCsGAQUFBwIBFhpodHRwOi8vY3BzLmxldHNlbmNyeXB0Lm9y ZzCCAQMGCisGAQQB1nkCBAIEgfQEgfEA7wB2AOJpS64m6OlACeiGG7Y7g9Q+5/50 iPukjyiTAZ3d8dv+AAABaxF1ApUAAAQDAEcwRQIgGvt1P3YI9iDIkicmKnWtdA4J vwiZqB6GoGQEBnFLQuECIQDUzbe30Y4kfobQTA0qLZ85jvNFDtRzbRd9wCPXwcqO uwB1ACk8UZZUyDlluqpQ/FgH1Ldvv1h6KXLcpMMM9OVFR/R4AAABaxF1ArgAAAQD AEYwRAIgQ/jYKgNmSMGEmyVgrVBClbEawnND/kPXIZx82My6ovYCIGctTKC5u6bJ J+zCRH5QrSKMF1lOtXDeNMgYlLx7JOKLMA0GCSqGSIb3DQEBCwUAA4IBAQAcxj0r mrqFY5KluKfki7LzlXLnYGDEnaTCX3WC4trR/zDsKwLT2z/ywWjQ5O/zKk/N1+ad 0Pk9DMe0jc/AmvYPgzII7rOYIv7FF/J8z4UKF0uuxjvwvAhXr/JDKvNMkOn3Rtrw agf0eu3xyXwUty6Iip0WfrSYHcy19OrXzwaSLdMdJ5hz9CY6D+7tLk0g2+xI7XnT D+gU1J+g291HfNJet2hzmJn/I7gUJdareqSI9HtXuHw1f+LcQflAhxaTPRGgm65F XpnF9tQvtRMJFWiIO9YSrKjq9gJaW3YlN7CTDzNqtjnA3+I8gT7jCqFHYAH3ZLMu 6fJy+BkrQctqjWWp -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/ MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT DkRTVCBSb290IENBIFgzMB4XDTE2MDMxNzE2NDA0NloXDTIxMDMxNzE2NDA0Nlow SjELMAkGA1UEBhMCVVMxFjAUBgNVBAoTDUxldCdzIEVuY3J5cHQxIzAhBgNVBAMT GkxldCdzIEVuY3J5cHQgQXV0aG9yaXR5IFgzMIIBIjANBgkqhkiG9w0BAQEFAAOC AQ8AMIIBCgKCAQEAnNMM8FrlLke3cl03g7NoYzDq1zUmGSXhvb418XCSL7e4S0EF q6meNQhY7LEqxGiHC6PjdeTm86dicbp5gWAf15Gan/PQeGdxyGkOlZHP/uaZ6WA8 SMx+yk13EiSdRxta67nsHjcAHJyse6cF6s5K671B5TaYucv9bTyWaN8jKkKQDIZ0 Z8h/pZq4UmEUEz9l6YKHy9v6Dlb2honzhT+Xhq+w3Brvaw2VFn3EK6BlspkENnWA a6xK8xuQSXgvopZPKiAlKQTGdMDQMc2PMTiVFrqoM7hD8bEfwzB/onkxEz0tNvjj /PIzark5McWvxI0NHWQWM6r6hCm21AvA2H3DkwIDAQABo4IBfTCCAXkwEgYDVR0T AQH/BAgwBgEB/wIBADAOBgNVHQ8BAf8EBAMCAYYwfwYIKwYBBQUHAQEEczBxMDIG CCsGAQUFBzABhiZodHRwOi8vaXNyZy50cnVzdGlkLm9jc3AuaWRlbnRydXN0LmNv bTA7BggrBgEFBQcwAoYvaHR0cDovL2FwcHMuaWRlbnRydXN0LmNvbS9yb290cy9k c3Ryb290Y2F4My5wN2MwHwYDVR0jBBgwFoAUxKexpHsscfrb4UuQdf/EFWCFiRAw VAYDVR0gBE0wSzAIBgZngQwBAgEwPwYLKwYBBAGC3xMBAQEwMDAuBggrBgEFBQcC ARYiaHR0cDovL2Nwcy5yb290LXgxLmxldHNlbmNyeXB0Lm9yZzA8BgNVHR8ENTAz MDGgL6AthitodHRwOi8vY3JsLmlkZW50cnVzdC5jb20vRFNUUk9PVENBWDNDUkwu Y3JsMB0GA1UdDgQWBBSoSmpjBH3duubRObemRWXv86jsoTANBgkqhkiG9w0BAQsF AAOCAQEA3TPXEfNjWDjdGBX7CVW+dla5cEilaUcne8IkCJLxWh9KEik3JHRRHGJo uM2VcGfl96S8TihRzZvoroed6ti6WqEBmtzw3Wodatg+VyOeph4EYpr/1wXKtx8/ wApIvJSwtmVi4MFU5aMqrSDE6ea73Mj2tcMyo5jMd6jmeWUHK8so/joWUoHOUgwu X4Po1QYz+3dszkDqMp4fklxBwXRsW10KXzPMTZ+sOPAveyxindmjkW8lGy+QsRlG PfZ+G6Z6h7mjem0Y+iWlkYcV4PIWL1iwBi8saCbGS5jN2p8M+X+Q7UNKEkROb3N6 KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg== -----END CERTIFICATE-----

Here is the remote server certificate:

-----BEGIN CERTIFICATE----- MIIFeTCCBGGgAwIBAgISBMC6zEv90htsFIzCbGOKGCpvMA0GCSqGSIb3DQEBCwUA MEoxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MSMwIQYDVQQD ExpMZXQncyBFbmNyeXB0IEF1dGhvcml0eSBYMzAeFw0yMDAxMjgwNTIzMjFaFw0y MDA0MjcwNTIzMjFaMBQxEjAQBgNVBAMMCSouZGFsLm5ldDCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAKk+ZRY6Kr4GUS9hU+AUvgUrRzffLS4ScDNvk88F HXKe6Yx3oJnMJEGC9a5I9nJATcItOa+Xk6NKFIsGQZhFOTkV9xvbaEw2KZ14SIKK NsffEqZeQ/TUdMaHTeDXJxj1gfa+W9FK6uO1TzKrYQamdegXAv55F6KLeIPTjZj3 77AkdWuddimY3rp0gK/R1e2tkFtP/0ZeWuu1M736b6dtjXFIhzw3G8wurbGfBgfO TebZL3Kw0X5qOlyMQyOyXXUyRZMqgW7PMloGtGQ/PJKoTzqNmyWO93QB28PGHDm8 WgnSdwgXlTmVrL9Vwnzb5FIfcM1ba5nzqDGeg7tG5RcQEGkCAwEAAaOCAo0wggKJ MA4GA1UdDwEB/wQEAwIFoDAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIw DAYDVR0TAQH/BAIwADAdBgNVHQ4EFgQUpVm+qZ/cdM/H1vr7emXvf14+/0AwHwYD VR0jBBgwFoAUqEpqYwR93brm0Tm3pkVl7/Oo7KEwbwYIKwYBBQUHAQEEYzBhMC4G CCsGAQUFBzABhiJodHRwOi8vb2NzcC5pbnQteDMubGV0c2VuY3J5cHQub3JnMC8G CCsGAQUFBzAChiNodHRwOi8vY2VydC5pbnQteDMubGV0c2VuY3J5cHQub3JnLzBD BgNVHREEPDA6ggkqLmRhbC5uZXSCDyouaWwudXMuZGFsLm5ldIIOKi5pcHY2LmRh bC5uZXSCDCoudXMuZGFsLm5ldDBMBgNVHSAERTBDMAgGBmeBDAECATA3BgsrBgEE AYLfEwEBATAoMCYGCCsGAQUFBwIBFhpodHRwOi8vY3BzLmxldHNlbmNyeXB0Lm9y ZzCCAQQGCisGAQQB1nkCBAIEgfUEgfIA8AB3ALIeBcyLos2KIE6HZvkruYolIGdr 2vpw57JJUy3vi5BeAAABb+rRlmkAAAQDAEgwRgIhAOG8C3vcxqEvj3TSqe7Y7peQ OInmtrkR0eQ9OFLVUIeUAiEAp0ONBILMiR2i0dVimSXFJv9NJDa3wi3tt3bRF5OO eDMAdQBvU3asMfAxGdiZAKRRFf93FRwR2QLBACkGjbIImjfZEwAAAW/q0ZafAAAE AwBGMEQCIBxS2C2cCPWFKKzof8BduUN6UFiWnyoRqAGAMG36IgylAiBjFDiXnuJs bVorvhguH6J9+YcPC36yFohKBCh+V7M0nzANBgkqhkiG9w0BAQsFAAOCAQEAnDE3 p/uxes7SKdspdwIhsC4Jwn3ulm4sGcbhJVBRWyYxp7ucGJdy/PxcEfb/CD5sszbw 9hsM56B7gno8ts/yNGvpceIoGEa7oK4AycEeWfapp5M9s11HyE06HwDfTA7wc1Kv g+PkHmbqZkLziN+UdPIlRm8dSljusvsNY1cMGRt5fszMJ5+gOaC3gj2AB6+aGIeN cwwNX3BlX10v88I3OUAkDWNlmPERA5BXo88ucZ75SwRZg7H8s66wdMYFi2LvbTHV GsXyDPVKnyViBtGCNI14UEmTDjUiHmqtzjqK2BTpSzNGYXjuPe1Zz0VIZDERPWin YxseV8k6nrZgr51Eag== -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/ MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT DkRTVCBSb290IENBIFgzMB4XDTE2MDMxNzE2NDA0NloXDTIxMDMxNzE2NDA0Nlow SjELMAkGA1UEBhMCVVMxFjAUBgNVBAoTDUxldCdzIEVuY3J5cHQxIzAhBgNVBAMT GkxldCdzIEVuY3J5cHQgQXV0aG9yaXR5IFgzMIIBIjANBgkqhkiG9w0BAQEFAAOC AQ8AMIIBCgKCAQEAnNMM8FrlLke3cl03g7NoYzDq1zUmGSXhvb418XCSL7e4S0EF q6meNQhY7LEqxGiHC6PjdeTm86dicbp5gWAf15Gan/PQeGdxyGkOlZHP/uaZ6WA8 SMx+yk13EiSdRxta67nsHjcAHJyse6cF6s5K671B5TaYucv9bTyWaN8jKkKQDIZ0 Z8h/pZq4UmEUEz9l6YKHy9v6Dlb2honzhT+Xhq+w3Brvaw2VFn3EK6BlspkENnWA a6xK8xuQSXgvopZPKiAlKQTGdMDQMc2PMTiVFrqoM7hD8bEfwzB/onkxEz0tNvjj /PIzark5McWvxI0NHWQWM6r6hCm21AvA2H3DkwIDAQABo4IBfTCCAXkwEgYDVR0T AQH/BAgwBgEB/wIBADAOBgNVHQ8BAf8EBAMCAYYwfwYIKwYBBQUHAQEEczBxMDIG CCsGAQUFBzABhiZodHRwOi8vaXNyZy50cnVzdGlkLm9jc3AuaWRlbnRydXN0LmNv bTA7BggrBgEFBQcwAoYvaHR0cDovL2FwcHMuaWRlbnRydXN0LmNvbS9yb290cy9k c3Ryb290Y2F4My5wN2MwHwYDVR0jBBgwFoAUxKexpHsscfrb4UuQdf/EFWCFiRAw VAYDVR0gBE0wSzAIBgZngQwBAgEwPwYLKwYBBAGC3xMBAQEwMDAuBggrBgEFBQcC ARYiaHR0cDovL2Nwcy5yb290LXgxLmxldHNlbmNyeXB0Lm9yZzA8BgNVHR8ENTAz MDGgL6AthitodHRwOi8vY3JsLmlkZW50cnVzdC5jb20vRFNUUk9PVENBWDNDUkwu Y3JsMB0GA1UdDgQWBBSoSmpjBH3duubRObemRWXv86jsoTANBgkqhkiG9w0BAQsF AAOCAQEA3TPXEfNjWDjdGBX7CVW+dla5cEilaUcne8IkCJLxWh9KEik3JHRRHGJo uM2VcGfl96S8TihRzZvoroed6ti6WqEBmtzw3Wodatg+VyOeph4EYpr/1wXKtx8/ wApIvJSwtmVi4MFU5aMqrSDE6ea73Mj2tcMyo5jMd6jmeWUHK8so/joWUoHOUgwu X4Po1QYz+3dszkDqMp4fklxBwXRsW10KXzPMTZ+sOPAveyxindmjkW8lGy+QsRlG PfZ+G6Z6h7mjem0Y+iWlkYcV4PIWL1iwBi8saCbGS5jN2p8M+X+Q7UNKEkROb3N6 KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg== -----END CERTIFICATE-----