CARP Status

Bob McClure h8msft at
Thu Sep 25 18:00:21 UTC 2008

Thanks to all for your input. With this many options on the table, I'm sure
one of them will meet my needs.



On Wed, Sep 24, 2008 at 11:23 AM, Oliver Fromme <olli at>wrote:

> Bob McClure <> wrote:
>  > I have several servers running CARP in an active/passive configuration.
>  > Currently the only way that my scripts can determine if a given node is
>  > master is by
>  > periodically executing ifconfig carp1 and grepping for MASTER. Although
> this
>  > works,
>  > it's kind of clunky.
>  >
>  > Is there a better way to detect the CARP status of a server?
> If you set sysctl net.inet.carp.log=2, you'll get a log
> entry every time the interface state changes.  You can
> configure a handler (e.g. a script) in /etc/syslog.conf
> that responds to such events.
> If you're a C programmer, you can also use the kqueue(2)
> API with EVFILT_NETDEV.  Then you will get a notification
> each time an interface link goes down or comes up.  See
> the kqueue(2) manual page for details.
> Finally, a third possibility is to use devd(8).  See the
> devd.conf(4) manual page for details.
> Best regards
>   Oliver
> --
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