Proper use of "allow/deny unknown-clients"?
Warner, Bill
bill.warner at earlywarning.com
Fri Aug 23 18:56:25 UTC 2013
Hi,
How can I split a sting based on a field separator. I've been using
option82 tags from the switch to help automate booting my big data (Hadoop
and cassandra) nfs/ramdisk root clusters. The circuit-id comes to me in the
form:
hostname:switchname
Of which I can use a line in dhcp.conf like:
option host-name = substring(option agent.circuit-id, 0, 8);
to automatically assign the hostname on boot.
To optimize operations we've changed the hostname convention slightly to the
effect of:
Hostnam:switchname
So the substing command wont pick up the correct hostname any longer as it
will include the ':'
What might I be able to do in order to split this string on the ':' rather
than start poing and number of chars?
Thanks,
-Bill
From: dhcp-users-bounces+bill.warner=earlywarning.com at lists.isc.org
[mailto:dhcp-users-bounces+bill.warner=earlywarning.com at lists.isc.org] On
Behalf Of John Miller
Sent: Tuesday, August 20, 2013 11:19 AM
To: Users of ISC DHCP
Subject: Re: Proper use of "allow/deny unknown-clients"?
On Tue, Aug 20, 2013 at 1:57 PM, Chris Buxton <clists at buxtonfamily.us>
wrote:
On Aug 20, 2013, at 10:54 AM, John Miller <johnmill at brandeis.edu> wrote:
> We're running into a seemingly odd issue: when we specify "allow
unknown-clients" within one of our address pools, known clients are no
longer to obtain IP addresses. When we remove the allow/deny rule
altogether, there's no problem with either known or unknown clients
connecting.
If you set an "allow" rule, anything not allowed is implicitly denied.
If you set a "deny" rule, anything not denied is implicitly allowed.
Ahh... that makes sense. I'd been making the assumption that since giving
no allow/deny directive allowed everything, that an explicit allow rule
wouldn't change that behavior. Sounds like this is not the case.
Appreciate the help, Chris.
John
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