# Enabling "Honor Cipher Order" on F5 LTM v12.X

Our SSL sites are receiving F's on ssllabs. The main reason is that we are vulnerable to the ROBOT vulnerability (We are upgrading from 12.1.1 to 12.1.3.4 tonight).

However another issue we are having is that the weak ciphers are closer to the top of the cipher list than the strong ciphers. This is the SSLlabs output:

TLS 1.2 (suites in server-preferred order)

TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x9f) DH 1024 bits FS WEAK256 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (0x9e) DH 1024 bits FS WEAK128 TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (0x6b) DH 1024 bits FS WEAK256 TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x39) DH 1024 bits FS WEAK256 TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (0x67) DH 1024 bits FS WEAK128 TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x33) DH 1024 bits FS WEAK128 TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (0x16) DH 1024 bits FS WEAK112 TLS_RSA_WITH_AES_256_GCM_SHA384 (0x9d) WEAK256 TLS_RSA_WITH_AES_128_GCM_SHA256 (0x9c) WEAK128 TLS_RSA_WITH_AES_256_CBC_SHA256 (0x3d) WEAK256 TLS_RSA_WITH_AES_256_CBC_SHA (0x35) WEAK256 TLS_RSA_WITH_AES_128_CBC_SHA256 (0x3c) WEAK128 TLS_RSA_WITH_AES_128_CBC_SHA (0x2f) WEAK128 TLS_RSA_WITH_3DES_EDE_CBC_SHA (0xa) WEAK112 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030) ECDH secp384r1 (eq. 7680 bits RSA) FS256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xc02f) ECDH secp384r1 (eq. 7680 bits RSA) FS128 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (0xc028) ECDH secp384r1 (eq. 7680 bits RSA) FS256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014) ECDH secp384r1 (eq. 7680 bits RSA) FS256 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (0xc027) ECDH secp384r1 (eq. 7680 bits RSA) FS128 TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013) ECDH secp384r1 (eq. 7680 bits RSA) FS128 TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (0xc012) ECDH secp384r1 (eq. 7680 bits RSA) FS WEAK112

We would like to start using this list of ciphers in order:

ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS

From what I have read so far, the F5 respects Cipher order from left to right and we need to use the shortnames to specify the ciphers.

Questions: (Any help is appreciated) 1. Do I change the ciphers in the default ssl_client profile? or do I change the ciphers in the DEFAULT cipher list? 2. How do I setup my list of cipher shortnames from the list above so that the F5 will use the correct ciphers in order? As a test I used "AES-GCM:AES:DES:!SSLV2:!SSLV3" in one of my VS ssl_client_profiles, but that didn't work. The cipher list on the bottom of ssllabs report was not in the correct order.