[Dnsmasq-discuss] adjustment for dhcp_release.c

[Simon Kelley]

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On 03/01/15 17:31, Rene Stoutjesdijk wrote:
> Hi Simon., thx for the quick response. As i'm rather new to this
> stuff. What is the Dbus and how can i make use out of it, or even
> better is there an example how you can delete a lease via the
> Dbus.
> 

DBus is an interprocess communication facility. It's used on Unix
systems to allow programs to "talk" to each other. In the this case,
you'd run a program called dbus-send to send a message to dnsmasq,
telling it to delete the lease. Except that you can't, as that hasn't
been implemented. Implementing that feature is the sensible way to do
this, rather the hack which is dhcp_release.

You can see what facilities are provided in the DBus interface to
dnsmasq in the file dbus/DBus-interface in the dnsmasq distribution
tarball.


Cheers,

Simon.


> wkr rene
> 
> 
> On Sat, Jan 3, 2015 at 6:21 PM, Simon Kelley
> <simon at thekelleys.org.uk> wrote: I think you're right about the
> problem.
> 
> The simplest solution would be to add code the dhcp_release to
> provide the same circuit-id information that the client would.
> 
> To be honest dhcp_release is a bit of a hack, and making it work
> in the general case probably isn't worth the effort. Much better
> would be to provide a method in the Dbus interface. The only
> inforamation actually required to identify a lease is the IP
> address, so a method to release the DHCP associated with a
> particular IPv4 or IPv6 lease would work great.
> 
> Patches carefully considered :)
> 
> 
> Cheers,
> 
> Simon.
> 
> 
> 
> On 03/01/15 17:14, Rene Stoutjesdijk wrote:
>>>> Goodday,
>>>> 
>>>> earlier today i did sent out an email (but probably something
>>>> went wrong) which i do repat later ,see QUOTED text at the
>>>> end of this email.
>>>> 
>>>> After the initial email i've done some additional tests, and
>>>> it looks like the dhcp_relase.c program is "only" working
>>>> when you provide information just out of a ip pool.
>>>> 
>>>> However when you provide ip addresses based upon an eg.
>>>> circuit-id then the address isn't cleared. As it looks like
>>>> the circuit-id (and maybe remote-id) are also checked upon
>>>> beofre doing the clearing.
>>>> 
>>>> Is above assumption correct, and if yes how can the
>>>> dhcp_release.c be adjusted so that also the cirucitid and/or
>>>> remote id can be provided.
>>>> 
>>>> 
>>>> i've als tested the above assumption with the following
>>>> scenario: do a dhcp DORA process based upon circuit-id CUST14
>>>> after the ip address was retrieved i changed the circuit-id
>>>> on the switch towards CUST14a then did a dhcp release from
>>>> the end station, and the lease file wasn't cleared.
>>>> 
>>>> then i changed the switch back to CUST14
>>>> 
>>>> i repeated above steps, and after the RELEASE message the
>>>> lease file was cleared for that entry.
>>>> 
>>>> so above mentioned assumption looks to be true
>>>> 
>>>> wkr rene
>>>> 
>>>> see text below for previous email, which apparently went
>>>> wrong).
>>>> 
>>>> QUOTE
>>>> 
>>>> Goodday,
>>>> 
>>>> i do have a question about dhcp_release.c
>>>> 
>>>> I'm trying to clear an entry within the dhcp lease table.
>>>> 
>>>> At this moment i'm providing the ip address based upon 
>>>> dhcp-circuitid. At this moment one of the en-users changed
>>>> his mac address and due to that resins he can't connect until
>>>> his old release is expired. So i wanted to clear manually his
>>>> old entry from the lease table.
>>>> 
>>>> For this i wanted to use the command:
>>>> 
>>>> ./dhcp_release eth1 10.64.1.0 a8:20:66:03:61:bc 
>>>> 01:a8:20:66:03:61:bc
>>>> 
>>>> 
>>>> based upon his entry within the lease file:
>>>> 
>>>> 1420293992 a8:20:66:03:61:bc 10.64.1.0 Renes-MBP 
>>>> 01:a8:20:66:03:61:bc
>>>> 
>>>> 
>>>> But as soon as i execute the command i do see the following
>>>> entry within the syslog file:
>>>> 
>>>> Jan  3 14:04:58 localhost dnsmasq-dhcp[3326]: 0 available
>>>> DHCP range: 10.64.1.0 -- 10.64.1.0
>>>> 
>>>> and the entry isn't cleared from the table (and the enduser
>>>> with his new mac address can't connect).
>>>> 
>>>> 
>>>> i do have a basic dhcp file which looks like:
>>>> 
>>>> dhcp-range=net:CUST14,10.64.1.0,10.64.1.0,255.192.0.0,4h 
>>>> dhcp-circuitid=CUST14,CUST14
>>>> 
>>>> 
>>>> 
>>>> 
>>>> What am i doing wrong?
>>>> 
>>>> thx in advance for your help.
>>>> 
>>>> UNQUOTE
>>>> 
> 
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