[CentOS] How to access the internet from load-balanced nodes?

Hello! I have set-up four nodes system: two LVS load balancers (CentOS) and two working nodes (openSUSE). LVS nodes have global IPs, so they able to access the internet and working nodes have only private IPs, so they cannot access internet directly. I use NAT-base load balancing.

Now I need to know how give working nodes ability to access the internet? I ask this because I don't know how to write properly iptables rules so LVS balancing packets will not conflict with working nodes internet connections. Should I assign some IP-alias for default gateway for that nodes or something else?

Thanks.