root@ip-10-33-30-103:~# apt-get install openswan
root@ip-10-33-30-103:~# cat /etc/ipsec.conf 
config setup
    protostack=netkey
    interfaces=%defaultroute
    nat_traversal=yes
    force_keepalive=yes
    keep_alive=60
    oe=no
    nhelpers=0
conn ToAWSSydneyVPC
    left=10.33.30.103
    leftsubnets=10.33.0.0/16
    leftid=@AwsChinaGW
    right=52.63.189.251
    rightsubnets=172.33.0.0/16
    rightid=@AwsSydneyGW
    forceencaps=yes
    authby=secret
    auto=ignore
 
root@ip-10-33-30-103:~# cat /etc/ipsec.secrets 
@AwsChinaGW  @AwsSydneyGW: PSK "123321112233"
 
root@ip-10-33-30-103:~# cat /etc/sysctl.conf | grep -v '^#' | grep -v '^$'
net.ipv4.ip_forward = 1
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.default.send_redirects = 0
 
root@ip-10-33-30-103:~# ipsec verify
root@ip-10-33-30-103:~# service ipsec start
root@ip-10-33-30-103:~# ipsec auto --add ToAWSSydneyVPC
root@ip-10-33-30-103:~# ipsec auto --up ToAWSSydneyVPC
root@ip-10-33-30-103:~# service ipsec status

root@ip-172-33-1-190:~# apt-get install openswan
root@ip-172-33-1-190:~# cat /etc/ipsec.conf 
config setup
    protostack=netkey
    interfaces=%defaultroute
    nat_traversal=yes
    force_keepalive=yes
    keep_alive=60
    oe=no
    nhelpers=0
conn ToAWSCnVPC
    left=172.33.1.190
    leftsubnets=172.33.0.0/16
    leftid=@AwsSydneyGW
    right=54.222.193.171
    rightsubnets=10.33.0.0/16
    rightid=@AwsChinaGW
    forceencaps=yes
    authby=secret
    auto=ignore
 
root@ip-172-33-1-190:~# cat /etc/ipsec.secrets 
@AwsSydneyGW  @AwsChinaGW: PSK "123321112233"
 
root@ip-172-33-1-190:~# cat /etc/sysctl.conf | grep -v '^#' | grep -v '^$'
net.ipv4.ip_forward = 1
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.default.send_redirects = 0
 
root@ip-172-33-1-190:~# ipsec verify
root@ip-172-33-1-190:~# service ipsec start
root@ip-172-33-1-190:~# ipsec auto --add ToAWSCnVPC
root@ip-172-33-1-190:~# ipsec auto --up ToAWSCnVPC
root@ip-172-33-1-190:~# service ipsec status