nat and dns

Alexis alexis at tpys.com.ar
Thu Sep 23 15:17:09 CEST 2004


Microsoft uses tcp for queries too.
 

-----Mensaje original-----
De: netfilter-bounces at lists.netfilter.org
[mailto:netfilter-bounces at lists.netfilter.org] En nombre de Samuel Díaz
García
Enviado el: Jueves, 23 de Septiembre de 2004 8:10
Para: Netfilter Mailing List
Asunto: Re: nat and dns

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 at arcoscom.com
http://www.arcoscom.com
móvil: 651 93 72 48
tlfn/fax: 956 70 13 15 







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