Eu encontrei a solução. Eu posso usar as tabelas NAT:
# the ip of node which is in MSD network. This can be for example edge node
IP_OF_SOURCE_NODE=50.50.50.1
# ip of destination database where we want to connect (do not forget on port)
IP_OF_DESTINATION_NODE=50.50.30.1:22
# ip address of VPN network adapter
IP_OF_VPN_NETWORK_ADAPTER=50.50.51.1
# Need to change the destination ip to database ip for the packets incoming from default network from specific source (for example dge node)
iptables -t nat -A PREROUTING -i ens5 -p tcp -s ${IP_OF_SOURCE_NODE} --dport 22 -j DNAT --to-destination ${IP_OF_DESTINATION_DATABASE}
# Need to change the source ip to inet address of vpn network address for packets leaving VPN network adapter
iptables -t nat -A POSTROUTING -o tun0 -p tcp -s ${IP_OF_SOURCE_NODE} --dport 22 -j SNAT --to-source ${IP_OF_VPN_NETWORK_ADAPTER}
Depois disso eu me conecto com sucesso ao nó 50.50.30.1 de 50.50.50.1 através de 50.50.40.1