[nsp] dns forwarding

[Eric Pylko]

The ip helper-address command forwards all sorts of broadcasts.  By default
it does DHCP and a bunch of others (tftp, dns, time (port 37), tacacs, bootp
client, bootp server, nb name service, and nb datagram service).  These are
all UDP ports that it forwards.

If you want to disable those (or enable others) you can do with with "no ip
forward-protocol" or "ip forward-protocol" as needed.

-Eric

--
Eric Pylko			eric at infinitenetworks.us
CCIE #5827			(585) 747-2446


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Kristofer Sigurdsson
Sent: Wednesday, July 07, 2004 1:01 PM
To: Roger
Cc: cisco-nsp at puck.nether.net
Subject: Re: [nsp] dns forwarding

Roger, Wed, Jul 07, 2004 at 11:48:11AM -0500 :
> Richard Danielli wrote:
> 
> >Roger,
> >
> >If you only have to satisfy client requests, you might consider looking
> >to the ip-helper address command in IOS. 
> > 
> >
> 
> Tried that..  Didn't work..  I put the helper address on the internal 
> interface and pointed the help-address to the dns server.
> 
> I tried a dns query on the ip of the router and it returned nothing.  
> From my understanding the helper-address forwards udp broadcasts - ie 
> for dhcp/bootp a dns query is a udp unicast. 

The helper-address directs BOOTP/DHCP IIRC - not broadcasts in general.

-- 
Kristófer Sigurðsson		   | Tel: +354 525 4103 / MSN: ks at rhi.hi.is
Netsérfræðingur/Network specialist | Reiknistofnun HÍ/University of Iceland
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