Dear Maintainer,

I believe I have found the exact bug anticipated by Sven Ulland in his
fix for #834532.  Here is a quote from his report:

Just to expand on Sven's description with my actual symptoms...  I have a
script which can restart dhclient rather abruptly (killall -9 dhclient;
dhclient wlan0).  Sometimes the IP address remains on the interface, and
then after dhclient restarts the valid_lft is not reset.  Then the kernel
kills the IP address after the lifetime runs out, but dhclient isn't
ready to renew the interface yet.  The connection is then dead until
dhclient renews on its own schedule (or it is manually restarted).

To work around it on my system, I simply found the two commands that set
valid_lft and replaced "ip -4 addr add" with "ip -4 addr replace".

I think this fix should be generally applicable.  Here's the trivial
patch:

http://galexander.org/x/0001-replace-IPv4-lifetime-instead-of-add-in-case-it-alre.patch

Hope this helps!  Thanks!

- Greg

Dear submitter,

as the package isc-dhcp has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143544

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

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Thorsten Alteholz (the ftpmaster behind the curtain)