Add options for overriding TLS ciphers used

[HuFlungDu]

Added some config options to allow the TLS ciphers used by Meshcentral to be configured by the user. Tested for working on the webserver, but I am not knowledgeable enough about the Meshcentral repo to know if this is all the changes that should be made to enable this ability.

[si458]

this is so nearly there!
you need to add the extra args to be allowed in meshcentral.js line 142 validArguments

[HuFlungDu]

Added the options to validArguments. Thanks!

[bmeirellesRJ]

Hello , where do I check the supported ciphers and order? How do I use TLS_CHACHA20_POLY1305_SHA256?

[si458]

@bmeirellesRJ is this what you are after? defaults below

MeshCentral/webserver.js

Lines 6112 to 6148 in 862e2ee

	var ciphers = [
	'TLS_AES_256_GCM_SHA384',
	'TLS_AES_128_GCM_SHA256',
	'TLS_AES_128_CCM_8_SHA256',
	'TLS_AES_128_CCM_SHA256',
	'TLS_CHACHA20_POLY1305_SHA256',
	'ECDHE-RSA-AES256-GCM-SHA384',
	'ECDHE-ECDSA-AES256-GCM-SHA384',
	'ECDHE-RSA-AES128-GCM-SHA256',
	'ECDHE-ECDSA-AES128-GCM-SHA256',
	'DHE-RSA-AES128-GCM-SHA256',
	'ECDHE-RSA-CHACHA20-POLY1305', // TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (0xcca8)
	'ECDHE-ARIA128-GCM-SHA256',
	'ECDHE-ARIA256-GCM-SHA384',
	'ECDHE-RSA-AES128-SHA256', // SSLlabs considers this cipher suite weak, but it's needed for older browers.
	'ECDHE-RSA-AES256-SHA384', // SSLlabs considers this cipher suite weak, but it's needed for older browers.
	'!aNULL',
	'!eNULL',
	'!EXPORT',
	'!DES',
	'!RC4',
	'!MD5',
	'!PSK',
	'!SRP',
	'!CAMELLIA'
	].join(':');
	if (obj.useNodeDefaultTLSCiphers) {
	ciphers = require("tls").DEFAULT_CIPHERS;
	}
	if (obj.tlsCiphers) {
	ciphers = obj.tlsCiphers;
	if (Array.isArray(obj.tlsCiphers)) {
	ciphers = obj.tlsCiphers.join(":");
	}
	}

to set your own, you set tlsCiphers: ['TLS_CHACHA20_POLY1305_SHA256'] under settings in your config.json