I have Apache 2.4.12 and OpenSSL 1.0.2d 9 Jul 2015

on Kubuntu 15.04

Can You suggest better than that in my case:

SSLOpenSSLConfCmd ECDHParameters Automatic

SSLOpenSSLConfCmd Curves secp521r1:secp384r1:prime256v1

Where in default-ssl.conf should I put that above, but please suggest better for my server, as it is newer than in thread.

Is brainpoolP512t1: RFC 5639 curve over a 512 bit prime field the strongest algorithm? But I need also to support all systems, so please help me.

openssl ecparam -list_curves

secp112r1 : SECG/WTLS curve over a 112 bit prime field

secp112r2 : SECG curve over a 112 bit prime field

secp128r1 : SECG curve over a 128 bit prime field

secp128r2 : SECG curve over a 128 bit prime field

secp160k1 : SECG curve over a 160 bit prime field

secp160r1 : SECG curve over a 160 bit prime field

secp160r2 : SECG/WTLS curve over a 160 bit prime field

secp192k1 : SECG curve over a 192 bit prime field

secp224k1 : SECG curve over a 224 bit prime field

secp224r1 : NIST/SECG curve over a 224 bit prime field

secp256k1 : SECG curve over a 256 bit prime field

secp384r1 : NIST/SECG curve over a 384 bit prime field

secp521r1 : NIST/SECG curve over a 521 bit prime field

prime192v1: NIST/X9.62/SECG curve over a 192 bit prime field

prime192v2: X9.62 curve over a 192 bit prime field

prime192v3: X9.62 curve over a 192 bit prime field

prime239v1: X9.62 curve over a 239 bit prime field

prime239v2: X9.62 curve over a 239 bit prime field

prime239v3: X9.62 curve over a 239 bit prime field

prime256v1: X9.62/SECG curve over a 256 bit prime field

sect113r1 : SECG curve over a 113 bit binary field

sect113r2 : SECG curve over a 113 bit binary field

sect131r1 : SECG/WTLS curve over a 131 bit binary field

sect131r2 : SECG curve over a 131 bit binary field

sect163k1 : NIST/SECG/WTLS curve over a 163 bit binary field

sect163r1 : SECG curve over a 163 bit binary field

sect163r2 : NIST/SECG curve over a 163 bit binary field

sect193r1 : SECG curve over a 193 bit binary field

sect193r2 : SECG curve over a 193 bit binary field

sect233k1 : NIST/SECG/WTLS curve over a 233 bit binary field

sect233r1 : NIST/SECG/WTLS curve over a 233 bit binary field

sect239k1 : SECG curve over a 239 bit binary field

sect283k1 : NIST/SECG curve over a 283 bit binary field

sect283r1 : NIST/SECG curve over a 283 bit binary field

sect409k1 : NIST/SECG curve over a 409 bit binary field

sect409r1 : NIST/SECG curve over a 409 bit binary field

sect571k1 : NIST/SECG curve over a 571 bit binary field

sect571r1 : NIST/SECG curve over a 571 bit binary field

c2pnb163v1: X9.62 curve over a 163 bit binary field

c2pnb163v2: X9.62 curve over a 163 bit binary field

c2pnb163v3: X9.62 curve over a 163 bit binary field

c2pnb176v1: X9.62 curve over a 176 bit binary field

c2tnb191v1: X9.62 curve over a 191 bit binary field

c2tnb191v2: X9.62 curve over a 191 bit binary field

c2tnb191v3: X9.62 curve over a 191 bit binary field

c2pnb208w1: X9.62 curve over a 208 bit binary field

c2tnb239v1: X9.62 curve over a 239 bit binary field

c2tnb239v2: X9.62 curve over a 239 bit binary field

c2tnb239v3: X9.62 curve over a 239 bit binary field

c2pnb272w1: X9.62 curve over a 272 bit binary field

c2pnb304w1: X9.62 curve over a 304 bit binary field

c2tnb359v1: X9.62 curve over a 359 bit binary field

c2pnb368w1: X9.62 curve over a 368 bit binary field

c2tnb431r1: X9.62 curve over a 431 bit binary field

wap-wsg-idm-ecid-wtls1: WTLS curve over a 113 bit binary field

wap-wsg-idm-ecid-wtls3: NIST/SECG/WTLS curve over a 163 bit binary field

wap-wsg-idm-ecid-wtls4: SECG curve over a 113 bit binary field

wap-wsg-idm-ecid-wtls5: X9.62 curve over a 163 bit binary field

wap-wsg-idm-ecid-wtls6: SECG/WTLS curve over a 112 bit prime field

wap-wsg-idm-ecid-wtls7: SECG/WTLS curve over a 160 bit prime field

wap-wsg-idm-ecid-wtls8: WTLS curve over a 112 bit prime field

wap-wsg-idm-ecid-wtls9: WTLS curve over a 160 bit prime field

wap-wsg-idm-ecid-wtls10: NIST/SECG/WTLS curve over a 233 bit binary field

wap-wsg-idm-ecid-wtls11: NIST/SECG/WTLS curve over a 233 bit binary field

wap-wsg-idm-ecid-wtls12: WTLS curvs over a 224 bit prime field

Oakley-EC2N-3:

IPSec/IKE/Oakley curve #3 over a 155 bit binary field.

Not suitable for ECDSA.

Questionable extension field!

Oakley-EC2N-4:

IPSec/IKE/Oakley curve #4 over a 185 bit binary field.

Not suitable for ECDSA.

Questionable extension field!

brainpoolP160r1: RFC 5639 curve over a 160 bit prime field

brainpoolP160t1: RFC 5639 curve over a 160 bit prime field

brainpoolP192r1: RFC 5639 curve over a 192 bit prime field

brainpoolP192t1: RFC 5639 curve over a 192 bit prime field

brainpoolP224r1: RFC 5639 curve over a 224 bit prime field

brainpoolP224t1: RFC 5639 curve over a 224 bit prime field

brainpoolP256r1: RFC 5639 curve over a 256 bit prime field

brainpoolP256t1: RFC 5639 curve over a 256 bit prime field

brainpoolP320r1: RFC 5639 curve over a 320 bit prime field

brainpoolP320t1: RFC 5639 curve over a 320 bit prime field

brainpoolP384r1: RFC 5639 curve over a 384 bit prime field

brainpoolP384t1: RFC 5639 curve over a 384 bit prime field

brainpoolP512r1: RFC 5639 curve over a 512 bit prime field

brainpoolP512t1: RFC 5639 curve over a 512 bit prime field