Re: nat and dns

[Samuel Díaz García <samueldg@xxxxxxxxxxxx>]

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. 

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