First I connected to server B’s vpn and ssh into server B from my local machine. Then I continue ssh into server A but fail.
Machine B with VPN and machine A both with private network setup. I’ve checked my ip when I connected to the vpn, the ip is machine B’s public ip.

The iptable rules are as follow:
(A)
sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT
sudo iptables -F
sudo iptables -A INPUT -p tcp -s <server B private ip> –dport 22 -i eth1 -j ACCEPT
sudo iptables -A OUTPUT -p tcp -d <server B private ip> –sport 22 -o eth1 -m state –state ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -i lo -j ACCEPT
sudo iptables -A OUTPUT -o lo -j ACCEPT

(B) openvpn
sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT
sudo iptables -F
sudo iptables -A INPUT -p tcp -s <server A private ip> –dport 22 -i eth1 -j ACCEPT
sudo iptables -A OUTPUT -p tcp -d <server A private ip> –sport 22 -o eth1 -m state –state ESTABLISHED -j ACCEPT
sudo iptables -A INPUT -i lo -j ACCEPT
sudo iptables -A OUTPUT -o lo -j ACCEPT
sudo iptables -I OUTPUT -o eth0 -d 0.0.0.0/0 -j ACCEPT
sudo iptables -I INPUT -i eth0 -m state –state ESTABLISHED,RELATED -j ACCEPT

What I’m trying to achieve is ssh from machine B into machine A with private network ip while connecting to machine’s B openvpn.

No other firewall setup because I am testing the behavior of iptable with openvpn. Anyone can help to explain? Thanks.