AWS ipsec.conf

# ipsec.conf
conn aws-to-gcp
  keyexchange=ikev1
  authby=secret
  type=tunnel
  left=172.xx.xx.4           #Host internal ip address
  leftid=aw
  leftsubnet=172.xx.0.0/16  #Host externa ip/Encryption domain
  right=35.xxx.xxx.28         #Peer2 ip address
  rightid=gcp
  rightsubnet=10.xxx.0.0/9 #Peer2 accesible intranet
  ike=3des-md5-modp1024     #Phase 1 integrity check algos
  esp=aes128-sha1-modp1024  #Phase 2 Encryption algos
  ikelifetime=28800
  lifetime=3600
  dpddelay=30
  dpdtimeout=120
  dpdaction=restart
  auto=start