"DHCPACK on" vs "DHCPACK to"

David W. Hankins David_Hankins at isc.org
Wed Dec 31 18:14:39 UTC 2008


These questions were probably more appropriate for dhcp-users@, just
so you know.  Kind of on the line either way, but I err towards users.

On Tue, Dec 30, 2008 at 11:25:05AM -0600, Judson Bishop wrote:
> I am writing a SyslogScan::Daemon plugin for NAT rule updates and have a
> question concerning DCHPACK in the log file.

I'm sorry; our log messages aren't very machine readable.

Have you considered using execute() statements on 'on commit' events
instead?  I think the folks who wrote that patch did it for similar
purposes (firewall rules, etc).

> Is it correct that "DHCPACK to" is for a new lease and "DCHPACK on" is for a
> renewal?  

No; 'DHCPACK to' is only logged in reply to a DHCPINFORM.  The 'to' is
intended to be literally the destination address, whereas on other DHCP
messages, it's quite possible a DHCPACK on a given leased address will
be directed to other destinations (the limited broadcast address, or a
relay agent).

Note that DHCPINFORM replies, even though they are DHCPACK's, do not
grant or extend a lease.

> Also, I am testing on isc-dhcpd-V3.0.5 and looked through the code for 4.1.0
> and only saw "DHCPACK to."  Has the logging verbiage changed in the 4.X
> releases?

No, the 'on ...' log message is conditionally either a DHCPACK or a
DHCPNAK, so it's not surprising a simple grep doesn't find it.  If you
want to see where the 'on' message is logged, grep for;

	'Say what we're doing\.\.\.'

Which is a comment directly above the log line.

-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins
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