Re: IP Vs DNS (nfcan: addressed to exclusive sender for this address)

[Jim Laurino <nfcan.x.jimlaur@dfgh.net>]

On 2005.10.11 17:04, Barry Fawthrop - barry@ttienterprises.org wrote:
> Greetings all
> 
> with an IPTABLES ruleset you can specify an IP address to be allowed/blocked
> iptables INPUT -s 12.12.12.12 -j ALLOW
> 
> But can this be done with a DNS name
> iptables INPUT -s www.name.com -j ALLOW

IPTABLES accepts DNS names, but the DNS lookup is performed
when the rule is placed in the kernel,
not when the rule is evaluated against a packet.
The kernel (netfilter) rules use ip address only.

To achieve what you want, I think you would have to
update the rule whenever the DNS mapping changed.

> 
> since 12.12.12.12 may be www.name.com but it can also be
> 12.12.15.12 or 12.15.12.19
> eg www.nasa.gov this address does vary depending on location and sometimes  
> time of day
> from a single point I can ping www.nasa.gov and get different IP addresses  
> for it.
> 
> Yet I would like to allow access but preferably not to a whole range.
> Also by allowing a DNS name then if a single IP addresses hosts many sites,  
> I can be specific about the site?
> 
> 
> Thanks in advance
> B
> 
> 
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>
-- 
Jim Laurino
nfcan.x.jimlaur@dfgh.net
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