core.certmanager: Move EECDH ciphers before EDH in default cipherstring The original intent of having kEDH before kEECDH was that if a `dhparam` file was specified, this would be interpreted as a preference by the admin for old and well-tested Diffie-Hellman key agreement over newer elliptic curve ones. Otherwise the faster elliptic curve ciphersuites would be preferred. This didn't really work as intended since this affects the ClientHello on outgoing s2s connections, leading to some servers using poorly configured kEDH. With Debian shipping OpenSSL settings that enforce a higher security level, this caused interoperability problems with servers that use DH params smaller than 2048 bits. E.g. jabber.org at the time of this writing has 1024 bit DH params. MattJ says > Curves have won, and OpenSSL is less weird about them now

--- a/core/certmanager.lua	Fri Aug 23 01:28:53 2019 +0200
+++ b/core/certmanager.lua	Sun Aug 25 20:22:35 2019 +0200
@@ -123,8 +123,8 @@
 		"P-521",
 	};
 	ciphers = {      -- Enabled ciphers in order of preference:
+		"HIGH+kEECDH", -- Ephemeral Elliptic curve Diffie-Hellman key exchange
 		"HIGH+kEDH",   -- Ephemeral Diffie-Hellman key exchange, if a 'dhparam' file is set
-		"HIGH+kEECDH", -- Ephemeral Elliptic curve Diffie-Hellman key exchange
 		"HIGH",        -- Other "High strength" ciphers
 		               -- Disabled cipher suites:
 		"!PSK",        -- Pre-Shared Key - not used for XMPP