I want to use Linux OpenVPN client for the tunnel.


OpenVPN Client Install

Insatll (Linux AMI 2)

# amazon-linux-extras install epel
# yum -y install openvpn easy-rsa iptables-services




# Copy autologin profile for auto login.

vi /etc/openvpn/client/vpn_cli01.conf

# Service start open VPN Client

systemctl status openvpn-client@vpn_cli01.service
systemctl start openvpn-client@vpn_cli01.service

# Kernel option


'net.ipv4.ip_forward' default = 0

I need to forward ipv4, so I change 0 -> 1


[ec2-user@ip-10-??-???-??? ~]$ cat /etc/sysctl.conf
# Kernel sysctl configuration file for Red Hat Linux
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
# Controls source route verification
net.ipv4.conf.default.rp_filter = 1
# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0
# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0
# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1
# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1
# Controls the default maxmimum size of a mesage queue
kernel.msgmnb = 65536
# Controls the maximum size of a message, in bytes
kernel.msgmax = 65536
# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736
# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296


# OpenVPN Setting on admin webpage

When I want to connect VPC1 -> VPC2 and set like this.

  • I assign to user : 192.168.xxx.xxx/16
  • VPC2 IPv4 CIDR :


# EC2 network setting

I'd like to use this EC2 instance for routing.

So, you must disable this option. (OpenVPN Server & Client both)


 When ip.src/dst is different block or allow option


# Setup Routing Table

You must consider request & response both routing table.

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