Libreswan(road) to Strongswan IKEv2 using PSK the initiator (road).
The initiator request and IP address using CP. The responder has an addresspool.

Note: this test currently fails for strongswan 5.6.1. libreswan initiator sends its
default proposal, using AES, AES_GCM and MODP2048 in the KE payload, but also accepting
ECP groups.

strongswan correctly accepts IKE_INIT:

Jan 21 21:27:39 10[CFG] received proposals: IKE:AES_GCM_16_256/PRF_HMAC_SHA2_512/PRF_HMAC_SHA2_256/PRF_HMAC_SHA1/MODP_2048/MODP_3072/MODP_4096/MODP_8192/ECP_256, IKE:AES_GCM_16_128/PRF_HMAC_SHA2_512/PRF_HMAC_SHA2_256/PRF_HMAC_SHA1/MODP_2048/MODP_3072/MODP_4096/MODP_8192/ECP_256, IKE:AES_CBC_256/HMAC_SHA2_512_256/HMAC_SHA2_256_128/HMAC_SHA1_96/PRF_HMAC_SHA2_512/PRF_HMAC_SHA2_256/PRF_HMAC_SHA1/MODP_2048/MODP_3072/MODP_4096/MODP_8192/ECP_256, IKE:AES_CBC_128/HMAC_SHA2_512_256/HMAC_SHA2_256_128/HMAC_SHA1_96/PRF_HMAC_SHA2_512/PRF_HMAC_SHA2_256/PRF_HMAC_SHA1/MODP_2048/MODP_3072/MODP_4096/MODP_8192/ECP_256
Jan 21 21:27:39 10[CFG] configured proposals: IKE:3DES_CBC/HMAC_MD5_96/PRF_HMAC_MD5/MODP_2048, IKE: , IKE: 
Jan 21 21:27:39 10[CFG] selected proposal: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_256

It should really have picked the DH group from the KE payload if that was an acceptable group. It was
because the log shows "configured proposals" including modp2048.

Selecting a proposal with ECP is sub-optimal.

It then continues to fail:

Jan 21 21:27:39 10[IKE] DH group MODP_2048 inacceptable, requesting ECP_256
Jan 21 21:27:39 10[ENC] added payload of type NOTIFY to message
Jan 21 21:27:39 10[ENC] order payloads in message
Jan 21 21:27:39 10[ENC] added payload of type NOTIFY to message
Jan 21 21:27:39 10[ENC] generating IKE_SA_INIT response 0 [ N(INVAL_KE) ]

