help with linux iptables ??!!!

dr.x · 11-12-2013, 12:54 AM

hi all ,
i will describe my issue first :
i have dns server with ip 11.11.11.11
sometime my client use dns 8.8.8.8 , and in this case , from cisco router , i redirect those dns requests to the dns server 11.11.11.11

""note that the packets has dst ip 8.8.8.8 not 1.1.1.1 but it reached to dns server with 1.1.1.1 ip""

the issue is :
the redirected packets still have the destination ip 8.8.8.8 not 11.11.11.11 ,
my question is how let the dns server 11.11.11.11 reply to these packets although its destination ip not 11.11.11.11 ????

i think it need some work with iptables so that dns server dont drop these packets.

with to help
regards

hussam.dh · 11-12-2013, 07:41 AM

Try this :
iptables -t nat -A PREROUTING -p udp --dport 53 -j DNAT --to-destination 11.11.11.11

Add this for tcp:
iptables -t nat -A PREROUTING -p tcp --dport 53 -j DNAT --to-destination 11.11.11.11