Re: dhclient renew

[Dan Williams <dcbw redhat com>]

On Tue, 2013-03-19 at 12:21 -0400, Pavel Simerda wrote:
> ----- Original Message -----
> > From: "Christoph Mathys" <eraserix gmail com>
> > I apologize if this is the wrong place to ask.
>
> No probem at all.
>  
> > Short: Does NM run dispatcher.d scripts if dhclient renews an IP? (NM
> > 0.9.4)
>
> From NM point of view, there's no reason to do that, it's not a connection/connectivity change.

That said, it *could* be IP address changes, route changes, DNS changes,
anything really, because the DHCP server can change any of these options
during the lease and we'll get them at renew.

NM does emit the 'dhcp4-change' and 'dhcp6-change' events to dispatcher
scripts on the dhclient BOUND, RENEW, REBOOT, and REBIND events.

> > Our dns deletes dynamic entries if they have not been updated for 20
> > days or so.
>
> So your DNS is updated by the client, not by the server. You could use cron for that, possibly. I don't 
> think you can run specific scripts from dhclient when it's run with NetworkManager's action binary instead 
> of dhclient-script, but let's wait for other responses. Therefore it looks like you want to get back the 
> DHCP-based scripting capabilities with NetworkManager. It would be possible to modify the NM dhclient 
> module.

Typically that's what dispatcher scripts are for; if we need more events
for dispatcher scripts then we should investigate adding them.
Currently there's up, down, dhcp4-change, dhcp6-change, and hostname.
See 'man NetworkManager' for more information.

But we do need ones for IPv6 addressing changes that are *not* dependent
on DHCPv6, because the IP configuration can change via RA when DHCP
isn't involved.

In reality, the DHCP change events are more for notifying scripts of all
the DHCP options that NM doesn't care about, but that scripts should
care about, like NTP servers, SIP servers, etc.

Dan

> > We create and maintain this entries using a dispatcher
> > script in NM. This works fine for normal clients that are shutdown at
> > the end of the day/week. If the client runs for several weeks, it
> > regularly renews its dhcp lease (5 days), which I see in the
> > corresponding *.lease-file from dhclient. But I don't see any
> > activity concerning NM or our dispatcher script in the logs.
> > After the 20 days
> > have passed, the dns entry of the client just vanishes and I need to
> > manually disconnect and reconnect to retrigger the dispatcher script.
>
> If it's 20 days, a cronjob checking for NM connection and acting upon it might be easier.
>
> Cheers,
>
> Pavel
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