New ZeroConf Spec

Carl Karsten carl at
Sun Jul 9 19:39:01 BST 2006

Scott James Remnant wrote:
> On Mon, 2006-07-03 at 20:48 -0700, Dan Kegel wrote:
>> There should be no exception: there should be no open ports by default.
> This isn't actually entirely true; we currently have two open ports by
> default:
> If you're on a network with DHCP, the DHCP client listens on UDP port 68
> to receive responses from the DHCP server.
> And every time you make a DNS query, a UDP port is opened to receive the
> response from the DNS server.

I think you are missing the meaning or intent of "no open ports" - when a client 
makes a request of a server, it waits for the response on a port.  That includes 
a web browser, dns, e-mail client, apt-get, IRC and anything else that talks to 
another box.

I can see how one could argue that these do open ports, therefor ubuntu does 
have open ports by default, but I think the most that would happen is the phrase 
"no open ports" would be changed to "no daemons listing on a port", which would 
not help anything :)

Carl K

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