Need help with LEASEQUERY..
Pat Winn
ptwinn at cimtel.net
Fri Jun 11 21:42:53 UTC 2010
Also, is there any way to have it send back any user
options set in the dhcpd.conf which show up in the
lease file?
For example, I have put into each of my network stanzas:
set myLocation = "<some network location>"
In the leases file, it gets added to the lease as:
set myLocation = "<some network location>"
Any way to ask for that information to be sent back
as part of the lease query response? I know the server
knows about it, but I see nothing in any docs about
how to try and retrieve it?
--
Patrick T. Winn
Senior Systems Engineer
Cimarron Telephone Co.
(918) 865-3311 x280 - office
(918) 606-6602 - cell
While counting 0's and 1's, Pat Winn said:
> All,
> I have *finally* managed to send a DHCPLEASEQUERY packet to
> dhcpd and get a DHCPLEASEACTIVE or DHCPLEASEUNKNOWN packet
> back...and am parsing it out to something useful.
>
> I fully intend on sharing this (PHP) code with everyone as
> soon as I clean it up a tad. :-)
>
> Now comes the next question..
> Now that I have a packet coming back, it has a default subset
> of info in it which doesn't quite meet my needs (sigh).
> Some of what I need to capture is coming back in that packet,
> and some of it seems accessible only via omshell or by
> parsing the leases file. Things like start/end times rather
> than just the current time left on the lease, etc.
>
> I tried adding options fields to the lease query packet after
> browsing through the rfc's..thinking it would send back the
> fields I'm inquiring about. Alas..I still only get the same
> info back as before I added the extra options. Using a sniffer,
> (Wireshark), I see that the packets are no different with or
> without the extra options in the lease query packet.
>
> I've not yet tried to dig in the C code for dhcpd..and am wondering.
> Am I not passing something correctly, or is this just "all you are
> going to get back..period" given the way the dhcpd code is written?
>
> Thought I'd ask to see if anyone knew before I spend time digging.
>
> Thanks!
>
> --
> Patrick T. Winn
> Senior Systems Engineer
> Cimarron Telephone Co.
> (918) 865-3311 x280 - office
> (918) 606-6602 - cell
>
>
>
>
> While counting 0's and 1's, roger murray said:
>> Hey,
>>
>> This code works for me to query a CNR DHCP server (Cisco's DHCP), I
>> haven't tested it with ISC, but might have the opportunity next week.
>> I use it too loop through 3 servers to find out which server a client
>> is on. 99% of the code is based on:
>> http://search.cpan.org/~shadinger/Net-DHCP-0.66/lib/Net/DHCP/Packet.pm
>> and the example Sending a LEASEQUERY (provided by John A. Murphy).
>> Hopefully it will be a little help.
>>
>> Best regards,
>>
>> Roger Murray
>>
>> #!/usr/bin/perl
>> # Simple DHCP client - send a LeaseQuery (by mac and receive the IP)
>> and receive the response
>> use strict;
>> use warnings;
>> use IO::Socket::INET;
>> use Net::DHCP::Packet;
>> use Net::DHCP::Constants;
>>
>> my $usage = "usage: $0 DHCP_CLIENT_MAC\n"; $ARGV[0] || die $usage;
>>
>> # loop through cnr-A-F looking for the client.
>> my $cnr;
>> #foreach $cnr (qw/ 1 2 3 4 5 6 /) {
>> foreach $cnr (qw/ 1 3 5 /) {
>> my $cnrip = "10.125.$cnr.11";
>> # create a socket
>> my $handle = IO::Socket::INET->new(Proto => 'udp',
>> Broadcast => 1,
>> PeerPort => '67',
>> LocalPort => '67',
>> Timeout => '1',
>> PeerAddr => $cnrip)
>> or die "socket: $@"; # yes, it uses $@ here
>>
>> # create DHCP Packet
>> my $inform = Net::DHCP::Packet->new(
>> op => BOOTREQUEST(),
>> Htype => '0',
>> Hlen => '6',
>> Ciaddr => '0',
>> Chaddr => $ARGV[0],
>> Giaddr => $handle->sockhost(),
>> Xid => int(rand(0xFFFFFFFF)), # random xid
>> DHO_DHCP_MESSAGE_TYPE() => DHCPLEASEQUERY
>> );
>>
>> # send request
>> $handle->send($inform->serialize()) or die "Error sending
>> LeaseQuery: $!\n";
>>
>> #receive response
>> $handle->recv(my $newmsg, 1024) or die;
>> my $packet = Net::DHCP::Packet->new($newmsg);
>> # this will print out the entire packet
>> # print $packet->toString();
>> # this will take the return packet and tell you which cnr it is on.
>> my $package = $packet->toString();
>> if ( $package =~ /ciaddr = 0.0.0.0/ ){
>> #print "not on $cnrip \n";
>> }elsif ( $package =~ /ciaddr =
>> ([\d]+)\.([\d]+)\.([\d]+)\.([\d]+)/) {
>> print "$ARGV[0] has ip $1\.$2\.$3\.$4 and is
>> on $cnrip \n"
>> }
>> }
>>
>>
>>
>> On Fri, May 21, 2010 at 3:37 PM, Jiri Popelka <jpopelka at redhat.com>
>> wrote:
>>> On 05/20/2010 06:04 PM, Pat Winn wrote:
>>>>
>>>> Matt,
>>>> That codebase is (rather ironically) what I stumbled across
>>>> and was using for a baseline when I started hacking away at this.
>>>>
>>>> I'm in the same boat as you...wanting to pull lease info from the
>>>> running daemon rather than looking at what is in the leases file.
>>>>
>>>
>>> Same here.
>>> If you find (or succeed in writing) some working
>>> LEASEQUERY sending piece of software (in whatever language)
>>> I would very much appreciate to see it, because I'm also in need of it.
>>> Thanks
>>>>
>>>> We are an isp and are in the process of switching from using radius
>>>> with user authentication for our dialup and dsl customers to DHCP.
>>>> As such, I need all the info I can glean for each session/lease for
>>>> logging purposes and some of the info we need isn't in the leases
>>>> file..so it's down to pulling from the running daemon.
>>>>
>>>> I've tried forking an omshell process to talk to the daemon and
>>>> pull the lease info back into PHP. It worked fine except that every
>>>> so often the omshell process hangs while connected to the daemon
>>>> and won't disconnect. When that happens, the daemon stops responding
>>>> to any new requests. Guessing it puts a lock on it's internal lease
>>>> objects while omshell is connected since it can alter things and
>>>> simply won't work until it disconnects...so that becomes an unusable
>>>> option (short of patching ISC's code which I'd rather not tamper
>>>> with).
>>>>
>>>> I've considered writing my own version of omshell in php but then
>>>> figured out I could send a leasequery packet to the running daemon
>>>> and get the same info back...without being connected to it like
>>>> omshell. So now it's down to...create a PHP class which can send and
>>>> receive a packet to get the info back that way and be able to re-use
>>>> said class in whatever php code I want to use it in.
>>>>
>>>> That is...IF..I can ever get dhcpd to acknowledge that it received
>>>> a lease query packet and actually respond to it. :-(
>>>>
>>>> I'm totally open for suggestions at this point, and open to working
>>>> in a collaborative fashion as well. Perhaps we could both benefit
>>>> from it. ;-)
>>>>
>>>> Thanks for your time and response!
>>>>
>>>>
>>>
>>> _______________________________________________
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>>> dhcp-hackers at lists.isc.org
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>>>
>>
>
>
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