Re: nat and dns

["Samuel Díaz García" <samueldg@arcoscom.com>]

For DNS query only UDP is necesary, not TCP.

Regards,

Nick Drage writes:

> On Thu, Sep 23, 2004 at 11:00:33AM +0200, Raphael Jacquot wrote:
>> hi,
>> I have a setup that looks like :
>>  _____                                ____
>> [     ] 192.168.0.100                [    ]
>> [ DNS ]------------------------------[ FW ]----
>> [_____]                192.168.0.254 [____] (isp)
>>
>> and I want the DNS to answer to queries from the outside
>> what's the proper way of doing this ?
>
> I'm presuming that you want to answer queries from everywhere, rather
> than just from specific hosts, in which case:
>
> iptables -t nat -A PREROUTING --destination $EXTERNAL_IP -p udp --dport
> 53 -j DNAT --to-destination 192.168.0.100
>
> iptables -t nat -A PREROUTING --destination $EXTERNAL_IP -p tcp --dport
> 53 -j DNAT --to-destination 192.168.0.100
>
> iptables -A FORWARD --destination 192.168.0.100 -p udp --dport 53 -j
> ACCEPT
>
> iptables -A FORWARD --destination 192.168.0.100 -p tcp --dport 53 -j
> ACCEPT
>
> iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
>
> I'd be interested to hear how you get on by the way, I'm not quite sure
> that my iptables rulebases are keeping state on DNS requests correctly.
>
> --
> mors omnia vincit
>



Samuel Díaz Garcí­a
Director Gerente
ArcosCom Wireless, S.L.L.

mailto:samueldg@arcoscom.com
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