Bug 222172 - Expired ticket => supposed DOS attempt on ISP
Expired ticket => supposed DOS attempt on ISP
Product: Fedora
Classification: Fedora
Component: krb5 (Show other bugs)
All Linux
medium Severity medium
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Assigned To: Nalin Dahyabhai
Brian Brock
Depends On:
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Reported: 2007-01-10 13:49 EST by Andrew Overholt
Modified: 2008-04-04 09:21 EDT (History)
3 users (show)

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2008-04-04 09:21:05 EDT
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Regression: ---
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RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Andrew Overholt 2007-01-10 13:49:23 EST
Description of problem:
If I have a kerberos ticket that needs to be re-keyed but my machine can't see
the kerberos server, my ISP claims that my machine "DOSs" their DNS servers with
attempts to resolve the kerberos server.  They told me it was happening
something like 20 times a second.  I got my internet access shutoff for a week
:(  It happened to me because I used my laptop at the office and did a kinit and
then took it home and used it after the ticket expired.  It even happens over
reboots if one isn't running something like tmpfs due to the keys being cached
in /tmp.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. kinit
2. disconnect from RH VPN (or ssh or whatever)
3. wait for > 24 h
Actual results:
Rogers (rogers.com) either warns you (first time) or kicks you off for a day or
a week.

Expected results:
No supposed DOS attack.

Additional info:
Is there something we can educate Rogers on?  Is this a bug in my krb5.conf?
Comment 1 Nalin Dahyabhai 2007-01-10 13:52:22 EST
Is there a krb5-auth-dialog process running, and is it crunching lots of CPU? 
This sounds like it would be a duplicate of bug #188301.
Comment 2 Andrew Overholt 2007-01-10 13:57:51 EST
I believe krb5-auth-dialog was running but I'm unable/unwilling to try this
again as I can't afford another week without access.  I know that will make it
hard to track this down and I'm sorry about that :(  If there's anything else I
can do, please let me know, Nalin.  Thanks.

Would it be krb5-auth-dialog doing the DNS attempts?
Comment 3 Nalin Dahyabhai 2007-01-10 14:05:29 EST
I would expect so, yes.  The dialog goes into a tight loop trying to acquire
credentials, and the first thing libkrb5 does each time it's called to do so is
attempt to resolve the names of your configured KDCs.

Can you point your resolv.conf at another system, even itself?  If
krb5-auth-dialog is pinning your CPU, you'll be able to verify that even if
resolv.conf lists a machine which isn't a DNS server.
Comment 4 Andrew Overholt 2007-01-10 14:12:46 EST
(In reply to comment #3)
> Can you point your resolv.conf at another system, even itself?  If
> krb5-auth-dialog is pinning your CPU, you'll be able to verify that even if
> resolv.conf lists a machine which isn't a DNS server.

I will try this tonight or tomorrow and report back.
Comment 5 Bug Zapper 2008-04-04 01:33:19 EDT
Fedora apologizes that these issues have not been resolved yet. We're
sorry it's taken so long for your bug to be properly triaged and acted
on. We appreciate the time you took to report this issue and want to
make sure no important bugs slip through the cracks.

If you're currently running a version of Fedora Core between 1 and 6,
please note that Fedora no longer maintains these releases. We strongly
encourage you to upgrade to a current Fedora release. In order to
refocus our efforts as a project we are flagging all of the open bugs
for releases which are no longer maintained and closing them.

If this bug is still open against Fedora Core 1 through 6, thirty days
from now, it will be closed 'WONTFIX'. If you can reporduce this bug in
the latest Fedora version, please change to the respective version. If
you are unable to do this, please add a comment to this bug requesting
the change.

Thanks for your help, and we apologize again that we haven't handled
these issues to this point.

The process we are following is outlined here:

We will be following the process here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this
doesn't happen again.

And if you'd like to join the bug triage team to help make things
better, check out http://fedoraproject.org/wiki/BugZappers
Comment 6 Andrew Overholt 2008-04-04 09:21:05 EDT
Sorry for never reporting back on this.  Let's close it.

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