Ben's notes

I've used the steps below to temporary redirect IP traffic, during migration to another host. Tested on CentOS 6.x

• Configure the kernel to allow forwarding:

  echo 1 > /proc/sys/net/ipv4/ip_forward

• Route traffic to destination:

  iptables -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to-destination 2.2.2.2:443

• Allow forwarding:

  iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
  iptables -A FORWARD -p tcp -d 2.2.2.2 --dport 443 -j ACCEPT

• Masquerade outgoing connections:

  iptables -t nat -A POSTROUTING -j MASQUERADE

• Show active rules:

  iptables -nvL -t nat

• Delete rules:
  • Find line numbers:

    iptables -nvL -t nat --line-numbers

  • Delete rules using line number:

    iptables -t nat -D <num>
    iptables -D FORWARD <num>