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Re: Password policy: possible DoS scenario
- To: Buchan Milne <email@example.com>
- Subject: Re: Password policy: possible DoS scenario
- From: Konstantin Boyandin <firstname.lastname@example.org>
- Date: Tue, 01 Mar 2011 14:01:14 +0600
- Cc: email@example.com
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01.03.2011 13:29, Buchan Milne writes:
> On Tuesday, 1 March 2011 07:23:41 Konstantin Boyandin wrote:
>> Thanks to everyone having answered me earlier, I've managed to set up
>> password policy on the OpenLDAP provided in CentOS 5.5 repositories
>> (current version 2.3.43).
>> The setup: we have password policy enabled for users accounts in our
>> intranet. After 5 unsuccessful attempts the account is blocked for short
>> duration (30 seconds).
>> Does that mean that anyone now can keep all the accounts blocked most of
>> the time?
> Well, you do the maths.
> But, surely you have enough monitoring in place that you would be able to
> notice a high rate of unsuccessful binds, so that the duration of "most of the
> time" would not be very long.
While I am talking of the intranet, I feel I am in control. Logs are
monitored and if someone causes repetitive account lockouts, it's easy
Problems can happen when there is need to open certain services from
outside (email, for example).
>> Am I right that if anyone enters someone else' incorrect
>> password 5 times (in the given case), they will block the target account
>> (regardless of what IP address the attacker was connecting from)?
> Yes. But, where is the line between a DoS and an attempt to break into an
> In either case, if this *is* only in your intranet, behaviour like this would
>> Narrower question: do password policy module developers plan to take
>> into account what IPs are used to connect (thus, blocking only access
>> from specific IPs)?
> Maybe you should provide a specific use case, besides "my users violate my
A typical use case is this. We make users change their passwords
regularly, password policy was introduced to further urge to use safer
Now imagine a person's email being checked regularly from outside the
intranet. After the specified attempts the account gets locked. The only
option we have in such a case is to firewall the address that sends
In case the locks are IP-bound, they would only affect those attempting
to gain access (regardless of whether those are legitimate or