SV: running script at the time of address lease

[Tapan]

Many thanks for your answers..
I am using fedora 14 with dhcpd 4.1.1-P1.

On Mon, Feb 14, 2011 at 9:55 PM, Glenn Satchell <glenn.satchell at uniq.com.au>
wrote:
> Hi Jon
>
> execute() was implemented in 3.1.0, so if you tried 3.0.x then it wouldn't
> recognise the command.
>
> It is not possible to get the output of the command executed, but you can
> test the exit status, so you might be able to do something with that.
Syntax
> details are in the dhcp-eval man page.
>
> I found this blog with some examples:
>
>
http://invalidmagic.wordpress.com/2010/03/27/magic-dhcp-stuff-isc-dynamic-host-configuration-protocol/

I also tested with same conf described in the above link. But it didn't
work.
Could anyone confirm, whether the above ex. is working or not or I missed
something.

>
> and this from the mailing list archives which is essentially the same
thing
> posted 2 years earlier:
>
> https://lists.isc.org/pipermail/dhcp-users/2008-September/007167.html
>
> regards,
> -glenn
>
> On 02/15/11 01:16, Jon Otterholm wrote:
>>
>> OK, I tried to make execute work on 3.x without any luck. Seems like it
>> is fixed in 4.x. Is it possible to do conditional leases now? In other
>> words: let an external script decide if the lease is OK or not (for
>> example based on option-82 info).
>>
>> //Jon
>>
>> *Från:*dhcp-users-bounces+jon.otterholm=ide.resurscentrum.se@
lists.isc.org
>>
>> [mailto:dhcp-users-bounces+jon.otterholm=ide.resurscentrum.se@
lists.isc.org]
>> *För *Denis Laventure
>> *Skickat:* den 14 februari 2011 14:53
>> *Till:* Users of ISC DHCP
>> *Ämne:* RE: running script at the time of address lease
>>
>> What about :
>>
>> on commit { execute("command") } ?
>>
>> from dhcp-eval man page :
>>
>> *execute (/command-path [, data-expr1, ... data-exprN]);/*
>>
>> The *execute* statement runs an external command. The first argument is
>> a string literal containing the name or path of the command to run. The
>> other arguments, if present, are either string literals or data-
>> expressions which evaluate to text strings, to be passed as command-line
>> arguments to the command.
>>
>> *execute*is synchronous; the program will block until the external
>> command being run has finished. Please note that lengthy program
>> execution (for example, in an "on commit" in dhcpd.conf) may result in
>> bad performance and timeouts. Only external applications with very short
>> execution times are suitable for use.
>>
>> Passing user-supplied data to an external application might be
>> dangerous. Make sure the external application checks input buffers for
>> validity. Non-printable ASCII characters will be converted into
>> dhcpd.conf language octal escapes ("777"), make sure your external
>> command handles them as such.
>>
>> It is possible to use the execute statement in any context, not only on
>> events. If you put it in a regular scope in the configuration file you
>> will execute that command every time a scope is evaluated.
>>
>> I’m running ISC DHCPD v. 4.2.0
>>
>> Denis
>>
>> *De :*dhcp-users-bounces+denis_laventure=uqac.ca at lists.isc.org
>> [mailto:dhcp-users-bounces+denis_laventure=uqac.ca at lists.isc.org] *De la
>> part de* Jon Otterholm
>> *Envoyé :* 14 février 2011 06:20
>> *À :* Users of ISC DHCP
>> *Objet :* SV: running script at the time of address lease
>>
>> The short answer is no, but there are ways to solve this.
>>
>> I use the exec function in syslog to execute scripts upon lease/expire.
>> You can configure dhcpd to do logging which includes the information you
>> need (IP, MAC …). Here is an example:
>>
>> Dhcpd.conf
>>
>> ______
>>
>> log-facility local6;
>>
>> on commit { log(info, concat("commit", " ", binary-to-ascii(10, 8, ".",
>> leased-address), " ", concat (
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 1,
>> 1))),2),":",
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 2,
>> 1))),2),":",
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 3,
>> 1))),2),":",
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 4,
>> 1))),2),":",
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 5,
>> 1))),2),":",
>>
>> suffix (concat ("0", binary-to-ascii (16, 8, "", substring(hardware, 6,
>> 1))),2)
>>
>> ), " ", "'", (option agent.circuit-id), "'"));
>>
>> }
>>
>> on expiry { log(info, concat("expiry", " ", binary-to-ascii(10, 8, ".",
>> leased-address)));
>>
>> }
>>
>> on release { log(info, concat("expiry", " ", binary-to-ascii(10, 8, ".",
>> leased-address)));
>>
>> }
>>
>> ___________
>>
>> Syslog.conf:
>>
>> ___
>>
>> local6.debug | exec /usr/bin/awk
>> '$6=="commit"{system("/usr/scripts/commit.sh" " " $7 " " $8 " " $9)}'
>>
>> local6.debug | exec /usr/bin/awk
>> '$6=="expiry"{system("/usr/scripts/release.sh" " " $7 " " $8 " " $9)}'
>>
>> ___
>>
Its quite interesting & also a generic way to handle many things.
I tried with rsyslogd ,but ... hard luck here also
>> As you can see dhcpd will log to local6.debug, syslog pipes info to awk
>> that filters info and sends it to a script together with necessary
>> variables. In this example it sends IP, MAC and Option-82 to the script.
>>
>> This runs on our FreeBSD-routers and it works really well. ~1000
>> customers/router and the lease-time is set to max 60min giving us about
>> 2000 leases to handle per hour.
>>
>> The advantage to this solution is the elimination of patches of dhcpd.
>>
>> Hope this info helps, good luck.
>>
>> //Jon
>>
>> *Från:*dhcp-users-bounces+jon.otterholm=ide.resurscentrum.se@
lists.isc.org
>>
>> [mailto:dhcp-users-bounces+jon.otterholm=ide.resurscentrum.se@
lists.isc.org]
>> *För *Tapan
>> *Skickat:* den 12 februari 2011 13:11
>> *Till:* dhcp-users at lists.isc.org
>> *Ämne:* running script at the time of address lease
>>
>> Hi list,
>> Is there any way to run a script from dhcpd after an address is assigned
>> to a host ?
>>
>> Regards,
>> Tapan
>>
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