Redirect requests mapped to a DNS IP Address

Question

For this command lines:

sysctl net.ipv4.ip_forward=1

iptables -t nat -A PREROUTING -p tcp --dport port -j DNAT --to-destination ip:port

iptables -t nat -A POSTROUTING -j MASQUERADE

I can reroute to ip:port

But how do I use a DNS instead? For example:

--to-destination mynetwork.dyndns.com:80

Answer 1

If you want to redirect DNS quries you can try this.

iptables -t nat -A PREROUTING -i ethX -p udp --dport 53 -j DNAT --to $(get lan_ipaddr)
iptables -t nat -A PREROUTING -i ethX -p tcp --dport 53 -j DNAT --to $(get lan_ipaddr)
iptables -t nat -L -v -n # shows nat table

and if you try to forward port 80 to another ip. Here is the rule and a example of it.

iptables -t nat -A PREROUTING -p ${PROTOCOL} -i ${INTERFACE} -d ${LOCAL_IP_ADDR} --dport ${LOCAL_PORT} -j DNAT --to ${DESTINATION_IP_ADDR}:{DESTINATION_PORT}
iptables -t nat -A PREROUTING -p tcp -i eth0 -d 192.168.1.10 --dport 80 -j DNAT --to 192.168.2.2:80

Please let me know in case of queries or if it was the answer of your question.