Secure server following best practices

[technicalguru]

e.g https://www.kuketz-blog.de/postfix-tls-konfiguration-mit-ecdsa-rsa-zertifikaten/

[technicalguru]

###########################################################
    testssl.sh       3.1dev from https://testssl.sh/dev/

      This program is free software. Distribution and
             modification under GPLv2 permitted.
      USAGE w/o ANY WARRANTY. USE IT AT YOUR OWN RISK!

       Please file bugs @ https://testssl.sh/bugs/

###########################################################

 Using "OpenSSL 1.0.2-chacha (1.0.2k-dev)" [~183 ciphers]
 on XXXX:./testssl.sh/bin/openssl.Linux.x86_64
 (built: "Jan 18 17:12:17 2019", platform: "linux-x86_64")


 Start 2021-06-09 13:27:09        -->> =======BLANKED======= <<--

 Further IP addresses:   =======BLANKED=======
 rDNS (=======BLANKED=======):   =======BLANKED=======.
 Service set:            STARTTLS via SMTP

 Testing protocols via sockets 

 SSLv2      not offered (OK)
 SSLv3      not offered (OK)
 TLS 1      offered (deprecated)
 TLS 1.1    offered (deprecated)
 TLS 1.2    offered (OK)
 TLS 1.3    offered (OK): final

 Testing cipher categories 

 NULL ciphers (no encryption)                      not offered (OK)
 Anonymous NULL Ciphers (no authentication)        not offered (OK)
 Export ciphers (w/o ADH+NULL)                     not offered (OK)
 LOW: 64 Bit + DES, RC[2,4], MD5 (w/o export)      not offered (OK)
 Triple DES Ciphers / IDEA                         not offered
 Obsoleted CBC ciphers (AES, ARIA etc.)            offered
 Strong encryption (AEAD ciphers) with no FS       not offered
 Forward Secrecy strong encryption (AEAD ciphers)  offered (OK)


 Testing server's cipher preferences 

 Has server cipher order?     no (NOT ok)
 Negotiated protocol          TLSv1.3
 Negotiated cipher            TLS_AES_256_GCM_SHA384, 253 bit ECDH (X25519) (limited sense as client will pick)
 Cipher per protocol

Hexcode  Cipher Suite Name (OpenSSL)       KeyExch.   Encryption  Bits     Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
SSLv2
 - 
SSLv3
 - 
TLSv1 (no server order, thus listed by strength)
 xc014   ECDHE-RSA-AES256-SHA              ECDH 521   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                 
 x39     DHE-RSA-AES256-SHA                DH 2048    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA                   
 x88     DHE-RSA-CAMELLIA256-SHA           DH 2048    Camellia    256      TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA              
 xc013   ECDHE-RSA-AES128-SHA              ECDH 521   AES         128      TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                 
 x33     DHE-RSA-AES128-SHA                DH 2048    AES         128      TLS_DHE_RSA_WITH_AES_128_CBC_SHA                   
 x45     DHE-RSA-CAMELLIA128-SHA           DH 2048    Camellia    128      TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA              
 x2f     AES128-SHA                        RSA        AES         128      TLS_RSA_WITH_AES_128_CBC_SHA                       
 x41     CAMELLIA128-SHA                   RSA        Camellia    128      TLS_RSA_WITH_CAMELLIA_128_CBC_SHA                  
TLSv1.1 (no server order, thus listed by strength)
 xc014   ECDHE-RSA-AES256-SHA              ECDH 521   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                 
 x39     DHE-RSA-AES256-SHA                DH 2048    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA                   
 x88     DHE-RSA-CAMELLIA256-SHA           DH 2048    Camellia    256      TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA              
 xc013   ECDHE-RSA-AES128-SHA              ECDH 521   AES         128      TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                 
 x33     DHE-RSA-AES128-SHA                DH 2048    AES         128      TLS_DHE_RSA_WITH_AES_128_CBC_SHA                   
 x45     DHE-RSA-CAMELLIA128-SHA           DH 2048    Camellia    128      TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA              
 x2f     AES128-SHA                        RSA        AES         128      TLS_RSA_WITH_AES_128_CBC_SHA                       
 x41     CAMELLIA128-SHA                   RSA        Camellia    128      TLS_RSA_WITH_CAMELLIA_128_CBC_SHA                  
TLSv1.2 (no server order, thus listed by strength)
 xc030   ECDHE-RSA-AES256-GCM-SHA384       ECDH 521   AESGCM      256      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384              
 xc028   ECDHE-RSA-AES256-SHA384           ECDH 521   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384              
 xc014   ECDHE-RSA-AES256-SHA              ECDH 521   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                 
 x9f     DHE-RSA-AES256-GCM-SHA384         DH 2048    AESGCM      256      TLS_DHE_RSA_WITH_AES_256_GCM_SHA384                
 xcca8   ECDHE-RSA-CHACHA20-POLY1305       ECDH 521   ChaCha20    256      TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256        
 xccaa   DHE-RSA-CHACHA20-POLY1305         DH 2048    ChaCha20    256      TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256          
 xc0a3   DHE-RSA-AES256-CCM8               DH 2048    AESCCM8     256      TLS_DHE_RSA_WITH_AES_256_CCM_8                     
 xc09f   DHE-RSA-AES256-CCM                DH 2048    AESCCM      256      TLS_DHE_RSA_WITH_AES_256_CCM                       
 x6b     DHE-RSA-AES256-SHA256             DH 2048    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA256                
 x39     DHE-RSA-AES256-SHA                DH 2048    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA                   
 xc077   ECDHE-RSA-CAMELLIA256-SHA384      ECDH 521   Camellia    256      TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384         
 xc4     DHE-RSA-CAMELLIA256-SHA256        DH 2048    Camellia    256      TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256           
 x88     DHE-RSA-CAMELLIA256-SHA           DH 2048    Camellia    256      TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA              
 xc053   DHE-RSA-ARIA256-GCM-SHA384        DH 2048    ARIAGCM     256      TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384               
 xc061   ECDHE-ARIA256-GCM-SHA384          ECDH 521   ARIAGCM     256      TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384             
 xc02f   ECDHE-RSA-AES128-GCM-SHA256       ECDH 521   AESGCM      128      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256              
 xc027   ECDHE-RSA-AES128-SHA256           ECDH 521   AES         128      TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256              
 xc013   ECDHE-RSA-AES128-SHA              ECDH 521   AES         128      TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                 
 x9e     DHE-RSA-AES128-GCM-SHA256         DH 2048    AESGCM      128      TLS_DHE_RSA_WITH_AES_128_GCM_SHA256                
 xc0a2   DHE-RSA-AES128-CCM8               DH 2048    AESCCM8     128      TLS_DHE_RSA_WITH_AES_128_CCM_8                     
 xc09e   DHE-RSA-AES128-CCM                DH 2048    AESCCM      128      TLS_DHE_RSA_WITH_AES_128_CCM                       
 x67     DHE-RSA-AES128-SHA256             DH 2048    AES         128      TLS_DHE_RSA_WITH_AES_128_CBC_SHA256                
 x33     DHE-RSA-AES128-SHA                DH 2048    AES         128      TLS_DHE_RSA_WITH_AES_128_CBC_SHA                   
 xc076   ECDHE-RSA-CAMELLIA128-SHA256      ECDH 521   Camellia    128      TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256         
 xbe     DHE-RSA-CAMELLIA128-SHA256        DH 2048    Camellia    128      TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256           
 x45     DHE-RSA-CAMELLIA128-SHA           DH 2048    Camellia    128      TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA              
 x2f     AES128-SHA                        RSA        AES         128      TLS_RSA_WITH_AES_128_CBC_SHA                       
 x41     CAMELLIA128-SHA                   RSA        Camellia    128      TLS_RSA_WITH_CAMELLIA_128_CBC_SHA                  
 xc052   DHE-RSA-ARIA128-GCM-SHA256        DH 2048    ARIAGCM     128      TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256               
 xc060   ECDHE-ARIA128-GCM-SHA256          ECDH 521   ARIAGCM     128      TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256             
TLSv1.3 (no server order, thus listed by strength)
 x1302   TLS_AES_256_GCM_SHA384            ECDH 253   AESGCM      256      TLS_AES_256_GCM_SHA384                             
 x1303   TLS_CHACHA20_POLY1305_SHA256      ECDH 253   ChaCha20    256      TLS_CHACHA20_POLY1305_SHA256                       
 x1301   TLS_AES_128_GCM_SHA256            ECDH 253   AESGCM      128      TLS_AES_128_GCM_SHA256                             


 Testing robust forward secrecy (FS) -- omitting Null Authentication/Encryption, 3DES, RC4 

 FS is offered (OK)           TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 ECDHE-RSA-AES256-GCM-SHA384 ECDHE-RSA-AES256-SHA384 ECDHE-RSA-AES256-SHA DHE-RSA-AES256-GCM-SHA384
                              ECDHE-RSA-CHACHA20-POLY1305 DHE-RSA-CHACHA20-POLY1305 DHE-RSA-AES256-CCM8 DHE-RSA-AES256-CCM DHE-RSA-AES256-SHA256 DHE-RSA-AES256-SHA
                              ECDHE-RSA-CAMELLIA256-SHA384 DHE-RSA-CAMELLIA256-SHA256 DHE-RSA-CAMELLIA256-SHA DHE-RSA-ARIA256-GCM-SHA384 ECDHE-ARIA256-GCM-SHA384
                              TLS_AES_128_GCM_SHA256 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-RSA-AES128-SHA256 ECDHE-RSA-AES128-SHA DHE-RSA-AES128-GCM-SHA256 DHE-RSA-AES128-CCM8
                              DHE-RSA-AES128-CCM DHE-RSA-AES128-SHA256 DHE-RSA-AES128-SHA ECDHE-RSA-CAMELLIA128-SHA256 DHE-RSA-CAMELLIA128-SHA256 DHE-RSA-CAMELLIA128-SHA
                              DHE-RSA-ARIA128-GCM-SHA256 ECDHE-ARIA128-GCM-SHA256 
 Elliptic curves offered:     prime256v1 secp384r1 secp521r1 X25519 X448 
 DH group offered:            Unknown DH group (2048 bits)

 Testing server defaults (Server Hello) 

 TLS extensions (standard)    "renegotiation info/#65281" "EC point formats/#11" "session ticket/#35" "supported versions/#43" "key share/#51" "supported_groups/#10"
                              "max fragment length/#1" "encrypt-then-mac/#22" "extended master secret/#23"
 Session Ticket RFC 5077 hint 7200 seconds, session tickets keys seems to be rotated < daily
 SSL Session ID support       yes
 Session Resumption           Tickets: yes, ID: yes
 TLS clock skew               Random values, no fingerprinting possible 
 Client Authentication        none
 Signature Algorithm          SHA256 with RSA
 Server key size              RSA 2048 bits (exponent is 65537)
 Server key usage             Digital Signature, Key Encipherment
 Server extended key usage    TLS Web Server Authentication, TLS Web Client Authentication
 Serial / Fingerprints        030632821534EE70642452BBE9AB3EB47867 / SHA1 1BB1E6ACC0C3F22100817E746189E87EF6EB0A18
                              SHA256 A05028790D8A4BE9962D510156FE86EEC792F2F539407377B19C9704A7119008
 Common Name (CN)             =======BLANKED=======
 subjectAltName (SAN)         =======BLANKED=======
 Trust (hostname)             Ok via SAN and CN (same w/o SNI)
 Chain of trust               Ok   
 EV cert (experimental)       no 
 Certificate Validity (UTC)   67 >= 30 days (2021-05-17 16:21 --> 2021-08-15 16:21)
 ETS/"eTLS", visibility info  not present
 Certificate Revocation List  --
 OCSP URI                     http://r3.o.lencr.org
 OCSP stapling                not offered
 OCSP must staple extension   --
 DNS CAA RR (experimental)    not offered
 Certificate Transparency     yes (certificate extension)
 Certificates provided        3
 Issuer                       R3 (Let's Encrypt from US)
 Intermediate cert validity   #1: ok > 40 days (2025-09-15 16:00). R3 <-- ISRG Root X1
                              #2: ok > 40 days (2024-09-30 18:14). ISRG Root X1 <-- DST Root CA X3
 Intermediate Bad OCSP (exp.) Ok


 Testing vulnerabilities 

 Heartbleed (CVE-2014-0160)                not vulnerable (OK), no heartbeat extension
 CCS (CVE-2014-0224)                       not vulnerable (OK)
 ROBOT                                     not vulnerable (OK)
 Secure Renegotiation (RFC 5746)           supported (OK)
 Secure Client-Initiated Renegotiation     VULNERABLE (NOT ok), potential DoS threat
 CRIME, TLS (CVE-2012-4929)                not vulnerable (OK) (not using HTTP anyway)
 POODLE, SSL (CVE-2014-3566)               not vulnerable (OK), no SSLv3 support
 TLS_FALLBACK_SCSV (RFC 7507)              Downgrade attack prevention supported (OK)
 SWEET32 (CVE-2016-2183, CVE-2016-6329)    not vulnerable (OK)
 FREAK (CVE-2015-0204)                     not vulnerable (OK)
 DROWN (CVE-2016-0800, CVE-2016-0703)      not vulnerable on this host and port (OK)
                                           make sure you don't use this certificate elsewhere with SSLv2 enabled services
                                           https://censys.io/ipv4?q=A05028790D8A4BE9962D510156FE86EEC792F2F539407377B19C9704A7119008 could help you to find out
 LOGJAM (CVE-2015-4000), experimental      not vulnerable (OK): no DH EXPORT ciphers, no common prime detected
 BEAST (CVE-2011-3389)                     TLS1: ECDHE-RSA-AES256-SHA DHE-RSA-AES256-SHA DHE-RSA-CAMELLIA256-SHA ECDHE-RSA-AES128-SHA DHE-RSA-AES128-SHA DHE-RSA-CAMELLIA128-SHA
                                                 AES128-SHA CAMELLIA128-SHA 
                                           VULNERABLE -- but also supports higher protocols  TLSv1.1 TLSv1.2 (likely mitigated)
 LUCKY13 (CVE-2013-0169), experimental     potentially VULNERABLE, uses cipher block chaining (CBC) ciphers with TLS. Check patches
 Winshock (CVE-2014-6321), experimental    not vulnerable (OK)
 RC4 (CVE-2013-2566, CVE-2015-2808)        no RC4 ciphers detected (OK)
 STARTTLS injection (experimental)         not vulnerable (OK)


 Running client simulations via sockets 

 Browser                      Protocol  Cipher Suite Name (OpenSSL)       Forward Secrecy
------------------------------------------------------------------------------------------------
 Android 8.1 (native)         TLSv1.2   ECDHE-RSA-AES128-GCM-SHA256       253 bit ECDH (X25519)
 Android 9.0 (native)         TLSv1.3   TLS_AES_128_GCM_SHA256            253 bit ECDH (X25519)
 Android 10.0 (native)        TLSv1.3   TLS_AES_128_GCM_SHA256            253 bit ECDH (X25519)
 Java 6u45                    TLSv1.0   AES128-SHA                        No FS
 Java 7u25                    TLSv1.0   ECDHE-RSA-AES128-SHA              256 bit ECDH (P-256)
 Java 8u161                   TLSv1.2   ECDHE-RSA-AES256-SHA384           256 bit ECDH (P-256)
 Java 11.0.2 (OpenJDK)        TLSv1.3   TLS_AES_128_GCM_SHA256            256 bit ECDH (P-256)
 Java 12.0.1 (OpenJDK)        TLSv1.3   TLS_AES_128_GCM_SHA256            256 bit ECDH (P-256)
 OpenSSL 1.0.2e               TLSv1.2   ECDHE-RSA-AES256-GCM-SHA384       256 bit ECDH (P-256)
 OpenSSL 1.1.0l (Debian)      TLSv1.2   ECDHE-RSA-AES256-GCM-SHA384       253 bit ECDH (X25519)
 OpenSSL 1.1.1d (Debian)      TLSv1.3   TLS_AES_256_GCM_SHA384            253 bit ECDH (X25519)


 Rating (experimental) 

 Rating specs (not complete)  SSL Labs's 'SSL Server Rating Guide' (version 2009q from 2020-01-30)
 Specification documentation  https://github.com/ssllabs/research/wiki/SSL-Server-Rating-Guide
 Protocol Support (weighted)  0 (0)
 Key Exchange     (weighted)  0 (0)
 Cipher Strength  (weighted)  0 (0)
 Final Score                  0
 Overall Grade                T
 Grade cap reasons            Grade capped to T. Encryption via STARTTLS is not mandatory (opportunistic).
                              Grade capped to B. TLS 1.1 offered
                              Grade capped to B. TLS 1.0 offered