CBC ciphers in relation to RFC7366 Encrypt-then-MAC

Stefan_Klotz Sadly I'm not 100% on this behavior but it is possible to change the cipher suite depending on what you see in the TCP connection utilizing an iRule. I am not positive if the iRule can be made to search for the "Encrypt-then-MAC" in the connection but a lot is possible via iRules so smoeone else who has a bit more experience with this setting might be able to assist you with the iRule in question.

Note that ECDSA & DSS will only work if your CERT supports them.  If you configure the ciphers, but the CERT doesn't allow it, they simply won't be offered/supported.  See https://my.f5.com/manage/s/article/K10340213 and https://my.f5.com/manage/s/article/K24121074 

There shouldn't be a problem with TLSv1.3 first - personally I think that's a good idea as any client that supports TLSv1.3 will use it, and only those that can't will fall back to TLSv1.2.  You may want to use !TLSv1:!TLSv1_1 - I'd also recommend disabling them on the Options for the VIP, and make sure TLSv1.3 is *enabled* (it is disabled by default): https://my.f5.com/manage/s/article/K33000012

Some scanners may ding you for DHE as it defaults to a 1024-bit key (while the key is rotated periodically scanners can't tell that).  We added support for larger DHE keys, but not until 16.1.3 and 17.0.0: https://my.f5.com/manage/s/article/K79342815

The Options List will always win.  Think of it this way - the Options List dictates which protocols are offered/accepted at all.  And then the Cipher configuration specifies which ciphers can be used by those protocols.

If a protocol is disabled in Options, it won't be agreed on in the handshake - so it doesn't matter if ciphers that work with it are enabled.  Conversely, if a protocol is enabled in Options it can be agreed on - but of no supporting ciphers are available to agree on.

The keywords in the Cipher config are not actually doing anything with regard to enabling/disabling the protocol, they're just shorthand to refer to *all* compatible ciphers.  So '!TLS1_1' doesn't actually turn off TLSv1.1, but it does mean no compatible ciphers will be available - and thus no connection can succeed.  Whereas 'No TLSv1.1' disables the entire protocol.  (This is also how people get themselves in trouble when they do things like "TLSv1.2" in ciphers, thereby enabling *all* compatible ciphers - including the truly awful ones.)

So you need to both remove 'No TLSv1.3' from Options *and* ensure the required ciphers are enabled for it to actually be used.

You're welcome.

Unfortunately, no, I'm not aware of any comprehensive command that would account for all variables.  For example, you can configure those ECDSA and DSS/DSA ciphers, and they'll show up with the 'tmm --clientcipher', but if the cert connected to that VIP doesn't support ECDSA/DSA then those ciphers will not actually be offered at all.  They just silently get disabled.

With the Options the ciphers are technically enabled and available, but since the protocol version is disabled they're just never called for.

It's hard to say, but if they're not disabled in the Options List it could be that the handshake is agreeing on TLSv1.0 or v1.1 as the protocol, and then failing when they can't find a cipher (since no cipher is enabled for those protocols).  Disabling then in the cipher configuration is not turning off the entire protocol, it is only disabling the ciphers - which means it will effectively fail to connect, but it may fail in a different way than if the protocol is disabled.